I. Introduction - II. Earth Sciences in Antiquity. 1. Geological Sciences in the Roman-Greek World . 2. Christianity and Early Scientific Thought . - III. Geology in the Middle Ages and in the Renaissance. 1. The Middle Ages . 2. The Renaissance . - IV. Geology in the Epoch of the Development of Scientific Method. 1. Geological Sciences in the 16th Century . 2. The Debate on the Nature of Fossils. - V. Developments and Results of Geology in the 18th and 19th Centuries. 1. The Origin of Mountains . 2. New Studies on Fossils . 3. The Debate on the Mechanisms which determined the Changing of the Earthly Surface . - VI. The Problem of the Age of the Earth - VII. Some Aspects of the Comparison between Geology and Theology in the Contemporary Era - VIII. Concluding Remarks.
Geology is the discipline that deals with the composition, structure and shape of the Earth and the phenomena occurring inside it, particularly on the surface, where access is more immediate. It is partly a physical science which, by examining the developments and mutations of the Earth, investigates their causes and links in order to draw up general laws; it is also a historical pursuit, since it seeks to reconstruct the transformations of the Earth through the ages up to its current form by observing its present condition. From this point of view, it is not an experimental science, as it deals with a succession of single events which may not be repeated over time.
Among natural sciences geology is one of the youngest. The word "geology", however, is much older and dates back to 1473, when it was introduced by Richard of Bury, Bishop of Durham, to define jurisprudence as an "earthly" doctrine, distinct from theology, a divine science. The word appeared for the first time in the sense closest to the present one in the posthumous work Geologia ovvero de fossilibus [ Geology or rather concerning fossils ] by Ulisse Aldrovandi (1522-1605). There are a number of pioneers of the subject. Some historians set the beginnings of geological sciences in the works of Agricola (1494-1555), who thanks to his innovative contributions is considered to be the father of mineralogy and a forerunner of geology. Fundator geologiae is held to be the Danish Niels Steensen (1638-1686), known in Italian as Stenone, for giving the first geological description of a region, Tuscany, and for defining the interpretative criteria of stratigraphic geology in his De solido intra solidum naturaliter contento dissertationis prodromus (1669). Yet the development of stratigraphy is usually associated with Giovanni Arduino (1714-1795) and William Smith (1769-1839). Geology's own scientific profile was raised by Abraham Gottlob Werner (1749-1817), who in the years 1786-91 proposed a theory of the Earth which was to remain predominant up to about 1820. He was the creator and herald of what was called "physical geology", that is, a geological study of the causes of changes and transformations on the Earth. The establishment of modern geology is attributed by some to James Hutton (1726-1797) for his two-volume Theory of the Earth (1795). Others look at the three-volume Principles of Geology (1830-33) by Charles Lyell (1797-1875) as a milestone in modern geology.
It was thus at the turn of the 19th century that geology became an autonomous discipline, with its own concerns and study methods. To be more precise, whereas geology has only recently become a science, humans have always had to resolve problems related to geological and geographical issues: how to identify a suitable site to build a city, where to find useful stones and metals, how to extract them and to process them, how to avoid landslides, how to use streams, how to capture waters, etc. Alongside the practical problems there were also theoretical pursuits: what is the shape of the Earth? How was it generated? What is its relationship with other bodies in the Universe? How did mountains, oceans, valleys, minerals originate?
Geology's path to become a science turned out to be a very long and strenuous one, both for the complexity and difficulty of the subject, and because the study of earthly phenomena was influenced by cultural factors in which philosophical and theological views were closely interconnected. Up to the end of the 19th century, the influence of these factors would still be felt. The study of the Earth entails problems of "genesis", on which human religions had had a say for a very long time with the "narratives of the origins", and philosophy had raised hypotheses based on more or less rational arguments.
The main concern of this presentation will be a historical comparison between the main religious and theological positions, particularly the Judaeo-Christian one, and a scientific study of the Earth. Our opting for the Judaeo-Christian tradition rests on obvious cultural grounds: geology as a science, and science more generally, was born in Europe from the encounter between the Judaeo-Christian world view and Greek philosophy. In adopting the historical method, we shall start precisely from the Greek world, where the issue of this cultural opposition was first raised.
II. Earth Sciences in Antiquity
1. Geological Sciences in the Roman-Greek World. At about the same time as Buddha was operating in India, Lao-Tse and Confucius in China and the great prophets in Israel, on the Ionian coasts of Asia Minor, some thinkers of Greek origin started to reflect upon the then predominant mythological views, according to which nature was the free manifestation of the free will of a plurality of gods. Philosophical reasoning gradually brought about inception of rational thinking, which saw in natural phenomenon much less the arbitrary whim of a godhead jealous of humans, than the manifestation of immanent laws, inscribed in nature itself.
This approach, which only later, with Christianity, would see nature being definitively stripped of its divine attributes, facilitated the free and unrestrained investigation of natural phenomena, of astronomy, zoology and botany in particular. Less attention was paid to earth sciences, in whose domains the treatises De mineralibus and Meteorologica by Aristotle were the most accomplished expressions at the time. In the subject areas associated with this discipline the focus was on fossils (described by Empedocles, Aristotle, Xenophanes), on earthquakes (caused by water or fire, earth or air, respectively according to Thales, Anaxagoras, Anaximenes, Archelaus), on stones (on the origin of which Aristotle advanced the theory of celestial influences and Theophrastus wrote a treatise) and marginally on mountains (Pythagoras, cited by Ovid in his Metamorphoses; Aristotle; Plutarch). Natural explanations, as opposed to mythical ones, were already found in Herodotus: the Nile floods were attributed to the annual motion of the sun and not to the gods' own action; the gorge of Mount Peneus to the effect of an earthquake and not to Poseidon's own intervention. In Anaximander there are also some innovative statements.
As to the origins of the Earth, it is generally associated with the origins of the cosmos. The mythical cosmogonies of earlier times were in time replaced by rational cosmogonies, that is cosmologies based on astronomical observations. The prevailing one was that of Claudius Ptolemy (100-178), which, based on Aristotle's thought, would dominate Europe's cultural framework for over fifteen centuries, until modern times. In his view, the Earth stands immovable, at the center of the Universe, which is finite and spherical, and around it rotate ten ancillary bodies of the Earth, one of which is the Sun. There is a sublunar world, imperfect, and a superlunar world, which is the place of perfection and the seat of quintessence. Matter is eternal, as the Universe is eternal, and the latter's life proceeds in cycles. The whole setup is governed by the First Cause, which is also the Prime Mover, the Supreme Good or Life, that is God.
Roman thinkers did not add much to Greek and Hellenistic speculations and observations. Subjects pertaining to geology, such as the shaping of mountains and depressions, landscape changes, volcanic eruption causes, erosion phenomena, etc. are found in the writings of Pliny the Old (23-79 d.C.), of Vitruvius and also accounted for both in poetic works (Ovid, Lucretius) and in literary ones (Seneca). Lucretius' (98- 55 a .C.) own attitude against religion, seen as superstition oppressing human life, was very thorough and harsh (cf. De Rerum Natura , I, 70-80).
The biblical standpoint is very different. The shaping of the Universe, of the Earth and of the human being are described in the first two chapters of Genesis. Jewish cosmology was partly indebted to the mythical visions then widespread amongst the Sumers and the Babylonians, but it differed from them in viewing the universe as a free creative act of a single God, distinct from His creation. The Universe had a beginning and knows no "eternal returns". The Old Testament integrated the idea of a flat-shaped Earth, encircled by the firmament dividing the upper from the lower waters. These views clashed with Greek thought in Alexandria of Egypt in the Hellenistic period, and the Jew, Philo of Alexandria (20 B.C. - 54 A.D.), was the first to seek a reconciliation between Biblical revelation and Greek philosophy.
2. Christianity and Early Scientific Thought. If we look at the New Testament, there are very few allusions to the physical nature of the world, but the adopted cosmology was still that of the Old Testament. Moving away from the Jewish context, in the course of evangelization Christianity confronted the Hellenistic thought, which contained both doctrines reconcilable with faith and doctrines which were much less adjustable. It took about four centuries for theologians to come to a preliminary synthesis between Christianity and Greek thought. The guiding criterion, however, had already been expressed by St. Justin (100-165 ca.), for whom all writers enjoyed some of the light of truth, because a seed of the Logos was placed in them. A fundamental problem was the interpretation of Scripture, tackled onwards by different theological schools from the 2nd century A.D. The conclusion of the school of Alexandria was that the Biblical message was not always expressed literally, but also contained an allegorical and a mystical meaning calling for investigation, whereas the school of Antiochia was favorable to literal interpretation.
On natural phenomena Basil of Cesarea (329-379), who was close to the school of Antiochia, wrote in his Hexaemeron: "There is much to be discovered through reasoning on the size and distance of the sun and of the moon by those want to make less than superficial observations [...]. Do not, then, measure the moon with our eyes, but with your reason, which is much more accurate than the eyes for the discovery of truth" (VI, 11, 4-5). St Augustine (354-430), who did not hold uniform views about Bible interpretation, however rejected the literal meaning of the Biblical statement according to which God had stretched the heavens like a tent, thus contributing to the assimilation of the spherical conception of the Universe, a distinctive element of Greek thought. Augustine became the advocate of a kind of exegesis which could be theologically respectful both of the Biblical data and of the knowledge of nature. If a passage of the Bible sounds absurd, he declared, this may happen "either because the text is wrong, or because the exegete has made a mistake, or because you have not grasped its meaning." (cf. Epistulae, 82, 1, 3; Contra Faustum, 11, 5). Commenting on Genesis in his Confessions, he taught that "two sorts of disagreements I see may arise, when a thing is in words related by true reporters; one, concerning the truth of the things, the other, concerning the meaning of the relater. For we enquire one way about the making of the creature, what is true; another way, what Moses, that excellent minister of Thy Faith, would have his reader and hearer understand by those words. For the first sort, away with all those who imagine themselves to know as a truth, what is false; and for this other, away with all them too, which imagine Moses to have written things that be false" (Confessiones , XII, 23). He advocated the multiplicity of interpretations: "Behold now, how foolish it is, in such abundance of most true meanings, as may be extracted out of those words, rashly to affirm, which of them Moses principally meant; and with pernicious contentions to offend charity itself, for whose sake he spake every thing, whose words we go about to expound" (ibidem, XII, 25); to conclude "if man demands of me, 'which of these was the meaning of Thy servant Moses'; this were not the language of my Confessions, should I not confess unto Thee, 'I know not'; and yet I know that those senses are true, those carnal ones excepted, of which I have spoken what seemed necessary" (XII, 30). And, finally, he added in De Genesi ad litteram: "It very often happens that regarding the earth, the heavens and other elements of this world, [...] even a pagan may possess such competent knowledge as to be able to defend it with an indisputable reasoning and on the basis of cultural experience" (I, 19, 39).
III. Geology in the Middle Ages and in the Renaissance
1. The Middle Ages. As early Medieval Europe experienced the disintegration of the Roman Empire and the migrations of different peoples, the times were most unsuitable to develop any kind of scientific pursuit. Christianity, however, had spread a different view of nature, which would more easily facilitate such a development in later centuries. A change in the political set up, an increase of trade, contacts with the Arab world, the acquaintance with the works of Greek and Arab thinkers would support the later cultural and intellectual awakening. This was the time of the great cultural syntheses, made in philosophy and theology by Thomas Aquinas (1225-1274) and in literature by Dante Alighieri (1265-1321).
The interest in stones and minerals increased, also as a result of the extractive activities, above all in Central Europe and in Italy. Lapidaries, i.e. treatises on the therapeutic, often magical, properties of precious stones, flourished, the most celebrated one being that of Marbod, Bishop of Rouen (1035-1123). A breath of novelty was felt with Albert the Great (1200 ca.-1280): he upheld the experimental method: "An experiment should be carried out not in one single way, but demonstrated in different circumstances [...]. Only thus can the experiment have a probative value"; he outlined clear criteria on the relationship between philosophy (including science) and theology: "When philosophers and theologians disagree, we have to trust Augustine in respect of what concerns faith and customs. But if we are dealing with a medicine, I would rather trust Hippocrates or Galen; and if we are dealing with physics, I trust Aristotle, because he is the one who has an excellent knowledge of nature" (cf. G. Saitta, Alberto Magno, "Enciclopedia Italiana," 1929, vol. II, p. 195). He showed a great interest in natural sciences and when writing De mineralibus he was no longer content with the authoritative opinions of ancient thinkers, but he went to mines for direct observation. The Franciscan Roger Bacon (1214-1292) also based his own method on the observation of nature, and as for Holy Scripture he highlighted some scientific imprecision and propounded a critical revision of the Vulgate. As concerns the interpretation of Holy Scripture, it is worthwhile noting the point of view of Thomas Aquinas (1225-1274), who maintained that with respect to things that relate to faith only incidentally, Christian authors have different opinions, interpreting the Sacred Scripture in various ways. "With respect to the origin of the world, there is one point that is of the substance of faith, viz., to know that it began by creation. [...] But the manner and the order according to which creation took place concerns the faith only incidentally." (In Book II Sententiarum, d. 12, q. 3, a. 1).
The first geological and natural interests go back to these times. For the monk Ristoro d'Arezzo, moved by an extraordinary spirit of observation, made clear in his work The Structure of the World (Composizione del mondo, 1282) that the Earth was shell-shaped with a central fused mass emanating forces responsible for the formation of mountains; he attributed to floods the erosion of mountains and the filling of valleys; he recognized sediments of marine origin from fossils, which he considered to be relics of the Flood --in this respect, he took up an idea already expressed by Tertullian (160-230) in his De Pallio. Fossils were also dealt with by Boccaccio (1313-1375) in his Filocolo and by Alessandro Alessandri (1461-1523). Albert the Great was concerned with volcanoes and with the erosive action of the sea. Dante in his tract Quaestio de terra et aqua interpreted the mechanism of rains and discussed the origin of meteoric waters. Iacopo Dondi (1298-1355) dealt with the saltiness of the sea, also tackling the problem of tides (which he already attributed to the combined effect of the sun, the moon and the planets); the evolution of landscape due to waters and winds was studied by L.B. Alberti (1404-1472); earthquakes interested Conrad of Megenburg (1309-1374), who attributed them to the action of vapours compressed in underground caves and moved by the power of the stars.
The Aristotelian and Ptolemaic world views that had been predominant up to that time began to be questioned by some clerics on the basis of philosophical and theological ideas as well as empirical observations. Jean Buridan (ca. 1300-1358) puts the question: "Is the Earth immobile at the world's center or not ?" and gives an equal number of arguments for and against. He supports the relativity of motion and assumes, as Aristotle, that the world is eternal, which he considers contrary to "our faith." His disciple, Nicholas of Oresme (1323-1382), bishop of Lisieux, debating the same question, brings forward ideas about the rotation of the Earth that anticipate Copernicus. As concerns the Holy Scripture, "which says that the sun revolves, etc.," he affirms: "one would say that it is in this part conforming to the manner of common human speech." Nicholas of Cusa (1401-1464), who was also a cardinal, claimed that the universe is infinite, the Earth could not occupy its center, it is a moving "noble star" and it is not the sole inhabited celestial body. For this he may be considered as the father of the cosmological principle, preceding Giordano Bruno (1548-1600).
We thus reach the threshold of the Modern Age. Europe was in a state of ferment. At the dawning of the Renaissance, new ideas mingled with traditional views, the clarification process being long and tiring. Modern Europe would eventually be born but it would take hard disputes and painful travail.
2. The Renaissance. Probably the most significant cultural event of the 16th century, of immense importance for science and for its consequences in the following century, was the printing in 1543 of De revolutionibus orbium coelestium by Copernicus (1473-1543), in which he expounded the theory of heliocentrism, as it would be called after him. The interests of the Renaissance were not restricted to astronomy, but came to embrace astrology, alchemy and magic, the latter being considered as scientific, or at least as exploring events related to scientific investigation; earth sciences also attracted increasing attention. The origin of earthly layers, the classification of minerals, the causes of earthquakes, the nature of fossils, the formation of sources and of mountains were also matters of repeated interest. We often encounter acute observations, with even modern insights, mostly carried out in an unsystematic and inorganic fashion, or at any rate moving within a context which suited the Biblical narrative in Genesis. A key role in this view was played by the great Flood at the time of Noah, held to be universal and taken as the starting point of a number of natural phenomena (the shaping of mountains, valleys, fossils).
It is precisely the study of "fossils" that spurred the imagination of scholars, who proposed the most diverse explanations, partly drawn from ancient times: objects fallen from the heavens, abortions of creation, sports of nature, fragments of giants or dragons, creatures of Satan, remnants of the Flood, and so on. Only a few attempts were made to look at things critically, scientifically as it were. Among those scientists we may mention Leonardo da Vinci (1452-1519), G. Fracastoro (1478-1553), G. Cardano (1501-1576), B. Palissy (1510-1590), A. Cesalpino (1519-1603), who came to recognize to true nature of fossils. Fracastoro observed that marine fossils could have not been formed at the time of the Flood, since they should be of fresh water and be found on the highlands, rather than being incorporated in rocks. A similar view was advocated by Leonardo, who interpreted natural phenomena on the basis of his own observations and of reasoning, independently of current opinions. From the study of fossil grounds he came to question «whether the flood occurred at the time of Noah was universal or not, and here it will be apparent that it was not, for the reasons given hereafter», and he highlighted the role of time in geological processes. Yet his insights, handed on by manuscripts which would only be published from the 19th century onwards, were ignored. The cleric G. Falloppio (1523-1562) said that those who considered the flood to give rise to mountains were mistaken. The issue of a critical comparison between scientific notions and the Biblical narrative started to be raised and it would return in dramatic terms some centuries later, when the mass of data and observations collected would demand such critical reconsideration.
Meanwhile, in the domain of earth sciences, mineralogy made a leap forward towards a modern kind of description, with the publication of two fundamental works by Georg Bauer, Latinised as Agricola (1494-1555): De natura fossilium (1546) and De re metallica (1556). They would be, respectively, the first systematic description of the minerals known up to that time, on the basis not of arbitrary qualities, of a magical and therapeutic kind, but of rational criteria and empirical properties (solubility, color, hardness, etc.), and the first original modern compendium of mineral art: mine prospecting and cultivation, mineral extraction and processing, with remarks of a geological nature (especially the shaping of mountains). With these two works, brilliantly summarizing the technical achievements of mining activity of previous generations, pruned of myths and legends, mineralogy and metallurgy were turned into modern sciences.
IV. Geology in the Epoch of the Development of Scientific Method
1. Geological Sciences in the 16th Century. The 16th century witnessed the first great divide between theology and science, occurring in the area of astronomy with the well-known Galileo affair, which was to become paradigmatic. Charged with strong ideological implications from the 19th century onwards, the case would have negative repercussions on the relations between Church and modernity, and in some instances even later misunderstandings would not be resolved on account of it.
In the fields of earth and natural sciences the relations between science and faith were friendly, in the sense that the great majority of scholars held nearly all the books of the Bible to be strictly historical, in particular --for what concerns us here-- the first chapters of the Book of Genesis on creation and the Flood. It is to notice that "with the development of the Reformation, there was increasing emphasis on the strict and literal interpretation of the Bible [...]. So in the XVII century, and more particularly in the Protestant parts of Europe, we get a serious effort to show that there was a satisfactory harmony between the words of the Bible and the emerging ideas of the new science." (Oldroyd, 1996, p. 48). The Earth would draw its origin from a chaotic watery phase: indeed "God made the dome, and He separated the water above the dome from the water below it" (Gen 1:7). From these waters as a result of gravity the solid parts deposited and contributed to shape the Earth. This view was in agreement, among other things, with the Aristotelian hypothesis of the formation of minerals by way of exhaling and more generally with the role assigned to water in the Classical world. The Flood was also attested in different cultures and further confirmation was found in the earliest pioneering geological field researches, which highlighted a number of phenomena (the re-dissolution and remixing of earthly material with more or less stratified sedimentation, fossil and mountain formation) which were easily compatible with the action of the Flood.
Remarks such as these particularly made in that specific historical situation were conducive to an attempt to define a chronology of earthly events taking the Biblical account of Creation as its starting point. According to the historian Delumeau, at the close of the 16th century, Europe witnessed great political, religious, demographic upheavals, which sustained the belief in the approaching end of the world (cf. Gohau, 1990, p. 82). The belief in the shortness of time left to human and cosmic life then spurred an interest in chronologies and was probably a precondition for the development of historical studies registered in the period in question.
Many attempted these kind of calculations, which were no mean feat, requiring competence in a range of areas (biblical, astronomical, historical) and Newton also made his own contributions. On the basis of Psalm 90:4: "A thousand years in your eyes are merely a yesterday" and of 2Pt 3:8: "with the Lord one day is like a thousand years and a thousand years like one day," it was reckoned that between Creation and the Last Judgment there should be no more than 6-7000 years. For the time between Creation and the birth of Christ, dates calculated range from 3900 to 5389 years, depending on whether one refers to the text of the Vulgate or to the Greek Septuagint. In 1541 Martin Luther reckoned 3960 years separated Creation and the birth of Jesus; persuaded that the Antichrist was reigning in Rome, he deduced that the Last Judgement would take place within about a hundred years. Christopher Columbus, for whom 5343 years had elapsed between the two events, would leave the world no more than 155 years for its completion as it would reach 7000. We owe the most precise pronouncements on the dating of Creation to John Lightfoot, the Vice Chancellor of the University of Cambridge, and to J. Ussher, the Anglican Archbishop of Armagh. The latter in 1650 determined that the Earth was created on October 26, 4004 B.C., at 9 a .m. This date was printed on the King James's Bible in 1701, a decision which would be criticized by Lyell in 1850. Ussher again reckoned that Noah's Ark came to rest on the Mount Ararat on May 6, 2349 B.C.
It is within this chronology that 17th-century naturalists would insert and appreciate the results of their inquiries. Thus, for example, the observation of the existence of multiple separate seas and lakes as against the original Biblical single expanse of waters raised the problem of their links, which was resolved with an hypothesis accounting for underground communicating canals. The antediluvian mountains were created directly by God and remained unchangeable, the postdiluvian ones were due to natural causes (cf. A. Kircher, Mundus subterraneus, 1664). Whereas on the one hand, the ever deeper investigations into the origin of water sources, the formation of mineral layers and the oceanic streams did not raise any particular problems, interesting new fact were learned from studying fossils.
2. The Debate on the Nature of Fossils. Three late 17th-century authors with their works contributed in different ways to lay the foundations of palaeontology as a science: Fabio Colonna (1567-1640), Robert Hooke (1635-1703) and Niels Steensen.
The first of these three scholars, in his De glossopetris dissertatio (1616), demonstrated the organic origin of the so-called "glossopetra" (megalodon shark fossil teeth). He demolished the view that also other fossils (then defined "pictured stones") should stem from real stones, and tackled the problem now known as "fossilization". However he did not go any further: the geological significance of fossils escapes him, for he did not see them in their formation context. The next step forward was taken by Steensen, who not only correctly interpreted the nature of fossils, using the same comparative method, but linked their genesis to that of the layers containing them. Not only fossils, but layers themselves can function as "the Earth's archives," because they incorporated past history in themselves. From the observations and data collected, handed on in his Prodromus (1669), "a truly revolutionary booklet" (cf. Gohau, 1990, p. 105), he became convinced that the Earth was subject to continuous modifications from the time of Creation onwards: "all the currently existing mountains, he said, did not exist from the inception of things." He thus anticipated the notions of cycle and of "geological era," which was to be of great importance for earth sciences; he introduced the principles of stratigraphy and he implicitly applied the "actualism principle," according to which the same forces operate now as they did in the past. He recognized the need for lengthy periods of time to witness the occurrence of geological events, with chronology remaining within the Biblical context, and was really pleased that the observations he made should confirm and validate the holy account. As a consequence, he mistakenly believed the large fossil bones discovered in the Arezzo countryside were the remnants of Hannibal's elephants.
Hooke shared with Steensen the same views on the nature and origin of fossils, and tackled the problem posed by those fossils having no current match. The main questions did not concern the disappearance of a species, given that Scripture contains "a great many expressions denoting continuous decay and a tendency towards final dissolution," but the formation of new species, which would require the repetition of the creative act. For Hooke, we would be faced with varieties due to climate and nutrition. A very religious man, Hooke saw the world to be that of the Bible, even though his own reading was not strictly of a literal kind, and he recognized that many natural phenomena need lengthy periods.
G.W. Leibniz (1646-1716) was also interested in the study of fossils, which he dealt with in his work entitled Protogaea (published posthumously in 1749). He wrote that he was convinced that "the figures of fish stamped on clay come from real fish and are no sports of nature," and he knew that in distant times there used to be fish which are no longer there, but he claimed that "in the great changes of the globe, a large number of shapes has been transformed." Quite a few other scholars studied fossils at the time. At the end of the century, whole remains of a mammoth were discovered in Siberia, of a megaceros elk in Ireland, of a fossil elephant in Gotha. These and other remains were then associated with the Flood, as a supernatural event (J. Woodward, 1695; W. Whiston, 1699). Only a few voices dared to challenge leading opinions: fossil shells were too heavy to have conceivably been carried by the Flood onto mountain tops (N. Quirini, 1676); there was no direct link between fossils and the Flood (G.W. Wedel, 1672). As for their genetic origin, there were scholars who still considered fossils to be lusus naturae ("sports of nature"), or products of a "stony virtue" combined with a "plastic virtue" (Kircher, 1664), and others who thought they were generated by seeds dispersed in the rocks (E. Lhwyd - Luidius, 1699).
Meanwhile the earliest "theory of the Earth," Telluris theoria sacra, by Rev. Thomas Burnet (1635-1715) was published in 1681, becoming the most popular 17th-century geology dissertation, which Charles II had translated into English and published three years later. It actually exposed a history of the Earth's shaping from an initial fluid chaotic mass, following an outline already suggested by Descartes in his Principia philosophiae (1644). The literal interpretation of the Biblical text then began to be criticized: Burnet voiced his own doubts regarding the length of the torrential rains of the Flood and reckoned that the volume of water necessary to cover the mountains should have been about eightfold that of the present oceans, which would lead to an unreasonable view of God's own work. The underlying notion was that God did create the Earth, but let it run its course, hence the Flood was not justified by supernatural, but by natural causes. It is worth noting that Burnet's work played a pivotal role in reversing interpretations current at that time: it was not science that confirms Moses' account, i.e. the Bible --as concordism would have it--, but it was rather in the latter that confirmation of one's own scientific ideas was to be found.
Other philosophical-literary works would further look at the Bible with a critical eye. In his Tractatus theologico-politicus (1670) Spinoza held that the Bible had to be handled just like any other historical document, a view which had already been expressed by Thomas Hobbes in his Leviathan (1651). The Oratorian Richard Simon (1638-1712) in his works Histoire critique du Vieux Testament (1678) and Histoire critique du texte du Nouveau Testament (1689) came to apply the canons of philology and of historical criticism to the Biblical text, getting as far as denying the Mosaic authority of Pentateuch and proposing a critical edition of the Bible. It was not yet time for such claims to be made: those two works were thus banned following Bossuet's intervention.
Yet the authority of the Biblical text in respect of historical dating was still held in very high esteem, even in the scientific arena. Religious irreverence, impiety and atheism, as a result of mistrust in the Bible were widespread fears. In 1690, the Anglican scientist Robert Boyle in his will left 50 pounds to organize apologetic lectures, later known as the Boyle Lectures , summoning all Christians to this event -the first example of ecumenism. In 1691 the botanist and zoologist John Ray, a friend of Steensen's, wrote a successful book, with a title that spoke for itself: The Wisdom of God Manifested in the Works of the Creation: this was the onset of Anglican Apologetics, as a form of natural Theology, referred to as Physico-Theology, which would play a major role at the time of the Enlightment.
V. Developments and Results of Geology in the 18th and 19th Centuries
In the 18th century, the study of the Earth, though still strictly bound to cosmology, was enhanced by a number of specific and significant contributions. A solution to the problem of the origin of sources was then found (Vallisnieri, 1715); modern oceanography was established (Marsili, 1725); modern crystallography and mineralogy began to develop (Haüy, 1780), along with the new-born stratigraphic palaeontology (Arduino, 1759; W. Smith, 1796).
The issues still prevailing in geologists' minds were still fossils, the age of the Earth, the origin of mountains and, as a general problem, the relationship between scientific observations and the Biblical text. One should not forget that the Enlightment was then holding sway, with its strong criticism of positive religions. The 18th century was that of Voltaire, Hume, Diderot, Rousseau, de Condillac, d'Holbach, Lessing, Kant. The spirit of Reason filled the study of science and was also gaining ground in religious contexts. Whereas in the previous centuries the Biblical account had served as a basis to reconstruct the history of the world, in the 18th century it was still taken into consideration, but it was rationalized, to the extent that at the turn of the century a geologist, J.A. de Luc, in his history of the Earth, still sought "new geological and historical proofs of Moses' divine mission."
Some of the burning issues of the relationship between geology and theological thought will be examined below.
1. The Origin of Mountains. It may seem odd that an apparently neutral subject should have theological implications. In fact, this had been the case ever since the earliest times, when reflection on Creation, the Flood and natural phenomena had started. Mountains were generally thought to date back to Creation. In 1708 J.J. Scheuchzer wrote: "God with his powerful hand has raised mountains." Mountains then originated before the flood and re-emerged from it as the waters subsided. Where did these waters end? According to some medieval writers (Severianus, Gabalas, the Venerable Bede, Peter Lombard), they moved into valleys intentionally made for that purpose by the Creator. According to others (John Philoponus) they gathered at the bottom of the oceans which had been previously emptied. Are the present mountains the same ones made at the beginning of creation? In the 17th century Steensen, to whom we owe the first scientific work on the origin of mountains, on the basis of his studies, had already argued that the present mountains had not existed since the beginning, nor did they grow by vegetation, but that they may have been originated by underground subsiding. In the 18th century, though referring to the Biblical account remained the standard procedure, the attempts to find natural explanations increased, as may be deduced from the following examples.
In 1740 Lazzaro Moro (1687-1740), a Venetian abbot, pointed to clear guiding principles for the study of natural phenomena. He observed the operations of nature and found conclusions exclusively on the facts observed. He also held that natural laws were uniform and unchangeable, and that nature always chose the most direct way. With these criteria in mind, he came to distinguish primary (not stratified) mountains from secondary (stratified) mountains. He accounted for the formation of volcanoes working on the hypothesis that the Earth would be made up of a crust and of an internal hollow filled with fused material, in this proving himself a precursor of Plutonism. He had a clear view of the origin and nature of fossils, he rejected Burnet's and Woodward's flood-based explanations, but as a pious believer he obeyed the Biblical text for the chronology. "It pleased the great Maker of all things, when the lands emerging above the waters appeared on the third day according to the holy account, that the great underground fires should be lit."
In his posthumous work Telliamed, B. De Maillet (1656-1738) viewed all rocks to originate from a primitive ocean, enfolding all the Earth. He tackled the issue of the origin of life, but he made no mention of Scripture: if the Flood did indeed take place, it was not a universal, but a local one. It was a definitely "materialistic" work, as Voltaire himself acknowledged. In 1749 the first three volumes of Buffon's monumental Histoire naturelle were published. He attempted to review the whole history of the Earth, which he imagined had originated from the impact of a comet with the Sun. The mountains were formed, he claimed, by the cooling of the fiery mass that had detached itself from it. In his theory there was no room for the universal Flood. In 1757 the Carmelite C. Generelli defended L. Moro's ideas on the origin of fossils and the rising of mountains; he discussed their compatibility with the Biblical account and remarked that the habit of resorting to the Bible often concealed a mischievous attempt to justify unsound theories which would not otherwise stand on their own. In the same era, the German scholar J.G. Lehmann (1756) would argue that primitive mountains, lacking fossils, rose by way of deposits of soil material from the waters which enfolded the Earth at the time of Creation. When the Flood came, as an "inexplicable enigma", along came the secondary mountains containing fossils. Local catastrophes formed the tertiary mountains, equally rich in fossils. The stratigraphic work was developed by G.C. Füchsel (1722-1773), who published the first geological maps, but his time-scale was restricted to some hundred of thousand years, and he tried to reconcile his geological findings with the Mosaic account (cf. Oldroyd, 1996, p. 79). The same idea was shared by P.S. Pallas (1777): the primitive granite mountains were formed at the time of Creation, and he reckoned that the sea waters piled up to a height of 640 feet . Biblical considerations were not excluded, but slowly declined in importance.
Two theories concerning the origin of mountains thus started to emerge: according to one of them they took shape from water ("Neptunist Theory", after Neptune, the god of the sea); according to the other, they did so from fire, that is from fused masses, lava or magma ("Plutonist Theory", after Pluto, the god of the Underworld). These theories were not equivalent, because the Neptunist theory seemed to be more in harmony with the Biblical view, which referred to expanses of water, and not to fire: Gn 1,9 indeed reads: "Then God said, 'Let the water under the sky be gathered into a single basin, so that the dry land may appear.' And so it happend." The subsequent Flood made it possible to explain the generation of fossils and their tracing on mountains even at a high altitude.
The most illustrious representative of the Neptunist school was A.L. Werner (1750-1817), who turned the Freiberg Mining Academy in Saxony into one of the most important European centers for geological research from the year 1775 to 1830. He developed the first systematic study of geological formations. Taking on board direct observation and the systematic study of the regions around Saxony, he was able to propose a stratigraphic classification. His original contribution was the inclusion of this classification within a Neptunist-oriented general theory, which would explain its origin (1787). In the beginning, the Earth was enfolded and submerged by the waters of a primordial ocean which contained dissolved or suspended, those substances that would later deposit to give rise to mountains. The history of the Earth was seen as a continuous succession of changes. Within this process, the role of time was essential: "Our Earth is born of time and it has gradually taken shape." He reckoned a million years as the age of the Earth. For taking no account of the Bible, Werner was accused of atheism, but indeed he was a deist.
One reason for sharp contrast between the two theories was the origin of basalt: had it taken shape by chemical precipitation from the universal ocean, as was claimed by the Neptunists, or by cooling from a lava, as was suggested by French (Desmarest, Soulavie, Dolomieu) and by Italian scientists (Breislak, Arduino), thus defined "volcanists"? As far as granite was concerned, the leading belief was that it was a primordial rock. What was its origin then? The problem was tackled, among others, by the Scotsman James Hutton (1726-97), who summarized his achievements in the treatise Theory of the Earth (1788), in which he demonstrated, on the basis of his observations on the rocks from Scotland, that basalt and granite originated from fire. They were propelled in a fused state onto the above layers by a force originating within the Earth due to the heat that developed there. On account of this view, Hutton and his followers were known as "Plutonists." By interpreting his observations on the basis of the hypothesis that the mechanisms of nature were uniform and constant, Hutton worked out a cyclical stationary model for the history of the Earth, in which erosion and rising cycles of "indefinite" length alternated. This in a nutshell is the "actualist principle," which would be so important in geology, though it had already been glimpsed by others, such as Füchsel, Moro, Carpenter, Linneus and drawn up by the Russian M.V. Lomonosov (1711-1765). From his studies Hutton derived the belief that «there is no reason to resort to hypothetical sins or to any other destructrive accidents or to a supernatural cause to explain what is there to be seen» and that in the rocks we find "no signs of a beginning, nor prospects of an end." For the view of the indefinite time of geological periods and the cyclical nature of earthly phenomena, he is taken to be the founder of modern geology.
Hutton's theory raised eyebrows for religious as well as scientific reasons: the mineralogist R. Kirwan (1733-1812), in particular, a fervent Neptunist and believer, criticized the fiery conception of granite and refuted the theory because it was not in harmony with the Biblical account of Creation. Moreover, stating that no signs of a beginning could be detected was in his opinion «contrary to reason and to the meaning of Moses' account, and led to an abyss which human reason shrinks from». In addition, the hypothesis regarding cycles of an indefinite length in Kirwan's view would virtually acknowledge the eternity of the world and was an outright profession of atheism (1793). Hutton would defend his own scientific ideas and rebut the claims of atheism (Hutton was actually a deist), arguing that his actualist principle did imply a divine blueprint: "in the history of the Earth --he wrote-- we are led to recognize an order of divine wisdom." The "lack of signs of a beginning" was simply the outcome of our research, he claimed: in reconstructing the geological past, "we come to a period, beyond which we are unable to gaze... My concern was to demonstrate how the structure of this world effectively responds to the intended goal, that is the preservation of animal life, which we cannot doubt." Kirwan counterattacked in his Geological Essays (1799), in which he demonstrated that the Neptunist theory he advocated, as a reworking of Werner's own theory, was in harmony with Holy Scripture.
At this point it is interesting to mention the view held by J.A. de Luc (1727-1817), as one of the pioneers of dynamic geology. In 1809 he wrote a treatise in which he subdivides the history of the Earth into two "eras": the first would include the processes that led to the shaping of mountains; the second has its origins approximately 4000 years ago with a catastrophic event, an immense flood over emerged lands. Having got to this result independently of the Biblical account, de Luc was pleased to have found confirmation in Holy Writ.
The dispute between Neptunists and Plutonists was very harsh and centered around the lively intellectual hub in Edinburgh. Later investigations in Britain and on the Continent, along with the first research activities of experimental geology run by J. Hall (1761-1832), determined the success of the Plutonist theory, which was almost universally accepted from 1820 onwards. The polemic came to an end, also because the study of fossils ignored by Neptunists and Plutonists, was leading to ground-breaking results providing geology with new prospects: the possibility of a correlation between layers containing fossils and the enunciation of the catastrophist principle.
2. New Studies on Fossils. In the 18th century the received notion was that fossils were remnants of organisms that lived in past times, some still extant, some extinct. Very few continued to believe they were due to the action of a plastic force operating within the rocks (J. Beringer, 1726). It was in that period that the word "fossil" was reserved to such category of materials, thus distinguishing them from minerals and rocks.
The fossils of extinct organisms posed a distressing problem to the believers of the time, who held Creation as perfect as soon as it had left God's creating hand: how could God have allowed the extinction of a living species created by him? Having bypassed this troubling question by resorting to the notions of divine omnipotence and wisdom, another problem arose: when and how did fossils originate? They were products of the Flood, the clearest evidence for it. This is the view adopted by most 18th-century scientists. The belief must have been so deeply rooted that a great palaeontologist, J.J. Scheuchzer, in 1726 mistook a huge fossil salamander, which will be recognized as such only in 1787, for the remnants of a man perished in the Flood! Investigations as well as discoveries and descriptions of new fossils would continue throughout the century --even Voltaire took an interest in them; meanwhile anatomic studies, essential for recognising the nature of fossils, also progressed.
A major contribution was made towards the close of the century by a great scientist, Georges Cuvier (1769-1832), the father of palaeontology as a science. He specifically dealt with fossil vertebrates, including extinct ones, succeeding in reconstructing their shapes thanks to his profound knowledge of comparative anatomy, and by applying the principle of organization of living beings, operating within a system made of correlated and interdependent parts (Discours sur les révolutions de la surface du globe, 1812). Invertebrate palaeontology, on the other hand, was pioneered by Jean-Baptiste de Monet, knight of Lamarck (1744-1829).
Interestingly the study of fossils led these two scientists to quite different developments and results. In the study of fossil-bearing grounds in the Parisian sedimentary basin, Cuvier observed that each of their layers could be distinguished from the others by the different fossils present, some of which matched extinct species. The changes of the fauna and the flora came to be attributed to sudden climatic catastrophes. It was the socalled "Catastrophist Theory," recasting ideas from previous centuries (Burnet, Whiston, Woodward): the disappearance of fauna and flora would be due to sudden violent causes, and new species would appear thereafter. The last of these catastrophic events must have taken place approximately 5000 years ago, as could be argued from the testimony of human history. Cuvier, who belonged to a refomed Church, allowed for the truthfulness of the Biblical flood, which was not the only catastrophic event, but it was the last one over a period of "thousands of ages." As for the origin of the new species, he did not make any clear-cut statements: "I would not posit the need for a new Creation-he claimed- to produce the existing species." (cf. Gohau, 1990, p. 309). Yet for him, as for Linneus, the species are fixed and do not change (a theory known as "fixism").
On the other hand, Lamarck's studies of fossil shells in the area of Paris led him to believe that, through the ages, species might be transformed into one another. Lamarck expounded the early notion of evolution in his Philosophie zoologique (1802), in which he attributed to the environment and to the organisms' own ability to adjust to it, the changes that species underwent through the ages, which would then be genetically transmitted. It is the doctrine known as "trasformism," a word coined by Lamarck himself in opposition to Cuvier's fixism, which would be extremely important for biological studies.
3. The Debate on the Mechanisms which determined the Changing of the Earthly Surface. The study of fossils had led Cuvier to formulate the "Catastrophist theory," whereas Hutton had advocated the uniformity and cyclical repetition of the mechanisms of nature. They were two clashing views and they would later catalyze geological disputes between 1790 and 1830. The debate also signalled the opposition between scientific and religious world view, since the Catastrophist theory seemed to be more compatible with the Biblical text. The stakes were high, as J. Towsend, a geologist and Methodist minister, argued in his work The Character of Moses established for veracity as an historian (1813). In his opinion, earth science would acquire enormous importance if we considered it in relation to our immortal hopes; the entire system of revealed religion was bound to Moses' own truthfulness; Christ's divine legacy and that of the Jewish legislator must stand or fall together; if the Biblical account turned out to be false, we should give up all our hopes.
How does nature proceed then? One answer was: "by catastrophes." Cuvier's catastrophist theory was confirmed by research carried out in France by competent scientists (Alexandre and Adolphe Brongniart, Elie de Beaumont) and, known in Britain from 1817, it was immediately accepted, for the majority of English geologists believed in the Flood and catastrophism was thought to confirm it. Some of the leading geologists of the time (Buckland, Conybeare, Sedgwick) were also influential members of the Anglican clergy, others (such as Whewell) were firm believers.
The best known English defender of the event of the Flood was the Oxford mineralogist and geologist, W. Buckland (1784-1856), whose first book bore the significant title: Vindiciae geologicae: or the Connexion of Geology with Religion Explained. He was persuaded of the veracity of the Biblical account, but differed from Towsend and other authors -whom we would nowadays call "fundamentalists"-- since he did not offer a literal interpretation for it. The six days of Creation were to be taken in an allegorical sense, hence the Earth could be very old. The Flood did indeed take place, was universal and could be confirmed by indisputable geological proofs, which he looked for in the caves of Europe, the Andes and the Himalaya. A synopsis of his discoveries may be found in a thrilling book, which was very popular, Reliquiae diluvianae (1823).
This concordist interpretation spurred isolated criticism. In 1826 a geologist and a member of the clergy himself, J. Fleming, by analysing the text of Genesis , proved that there was no match between the Biblical account and geological facts as science would envisage them: for instance, the Mosaic description of the Flood would not refer to a catastrophic event, but rather to a quiet rising of waters. Even Hutton rejected catastrophism, not only because it contradicted his own experience as a geologist, but also because he considered it to be unworthy of the divine blueprint: the changes were meant to be gradual and orderly. G.P. Scrope (1797-1876), who also refuted the reality of the biblical Flood, was very critical towards any attempt to reconcile geological science with the Biblical view, potentially jeopardising the unity of geology and slowing down the progress of research. Yet catastrophism stood unrivalled on the geological scene up to 1830, the year when the first of the three volumes of Principles of Geology by Charles Lyell (1797-1875) was published.
In these volumes Lyell collected the results of his own research work, based on direct field work expeditions in France and in Italy, and presented the second answer to the question regarding the workings of nature: changes would occur "gradually." In the first volume of his work he attempted to explain previous changes of the earthly surface with reference to causes operating now. For Lyell geology was not so much "a history of the Earth," as "a history of the changes occurred on the surface of this," which was the only accessible reality. His discoveries led him to conclude that since the earliest times no other causes have been in operation than those operating now, and these have never acted at any levels of energy other than the current ones. This is the principle of actualism. Moreover, changes occurring on the earthly surface were gradual ones, and the energy of underground movements has always been uniform. This is the principle of uniformity. It followed that the transformation times must have been very long. Lyell was not interested either in the origin, or in the age of the Earth, but wished to show the vastness of geological times. He reckoned, for instance, that a more than 130 meter thick sedimentary deposit must have taken over a hundred thousand years to grow. On the basis of such principles and on the assumption that the laws were permanent and unchangeable, it would then be possible to proceed, by analogy with the present, to the reconstruction of the past.
In the first volume, as the first complete history of geology, Lyell examined the causes that delayed geological studies, and identified one of these in the prejudice regarding the brevity of the past. This amounted to an implicit attack against the Bible. Not only against the dating, but also against the whole view of the Universal Flood as a catastrophic event. The book was immediately very successful. Reactions followed at short distance. King's College clergy, to whom Lyell applied for the Chair in Mineralogy and Geology, recognized that the book contained no hostile sentiments against revealed Truth. However, an influent member of the College's Faculty put a veto on it, for he did not want faith in Creation and in the Universal Flood to be weakened. Lyell, who was a deist, replied that he did not wish to dispense with the intervention of the First Cause in the creation of the species (for which he referred them to the second volume), nor did he cast doubt on the view concerning the creation of the human being within the allotted time; as for the flood, there was plenty of evidence that it had not covered the whole Earth. In a lecture at King's College, to which he was eventually admitted, he gave a more precise explanation: true religion might not be possibly affected by any ascertained facts nor did any other science offer a greater number of illustrations of the power and wisdom apparent in Creation than Geology (for the terms of this debate, cf. Klaver, 1997, pp. 47-50). Various scientific objections came from the geological circles.
By that time though the Biblical view of the Universal Flood was unsustainable: Conybeare, Buckland and Sedgwick, who had advocated the theory of the Flood, abandoned it, and in fact Sedgwick made a public retraction of what had by then become "a philosophical heresy." In 1834 the young, later Cardinal J.H. Newman, condemned the mistake of deducing geological theories from Scripture. The three volumes of Lyell's Principles of Geology had by now marked a complete reversal in the history of geology. They had a huge influence, essentially for the heuristic principle driving them. Charles Darwin (1809-1882), breaking his vow of not reading any more geology books after Jameson's lectures, one of Werner's pupils, brought a copy of the first volume on his tour on the Beagle (1831-1836) and recognized its usefulness for his own views. In effect he incorporated into his own theory a number of Lyell's ideas, the most important ones being the antiquity of the Earth and gradualism. It is worth noting that Lyell continued to reject the transmutation of the species. Faced with the appearance of new species recorded by stratigraphy, he confessed his ignorance. By creation of a species he meant the onset of a new series of organic phenomena. Whether these beginnings were brought about by direct intervention of the First Cause, or by any unknown Second Cause or Law fixed by the Author of Nature, is a point on which Lyell neither wanted to embark nor make any suggestions (cf. Hallam, 1983; cf. also Klaver, 1997, ch. V). It is interesting to observe that in their polemic against the supportes of the Flood, actualists rejected not only the hypothesis of the Flood, but the whole set of their theories, some of which were extremely valuable (such as tectonics and stratigraphy), with heavy repercussions on the future developments of geology itself.
The actualist view seemed to be questioned by the glaciations theory enounced in 1837 by the Swiss scientist L. Agassiz to explain the presence of huge erratic stones and other phenomena in Swiss valleys and planes. The growth of great ice expanses that had covered the whole earthly surface had been a catastrophic event which had caused the disappearance of some species. With the glaciers withdrawal new forms of life had appeared. This theory, softened in its most catastrophic aspect, could eventually be integrated into Lyell's actualist view. Yet a more serious attack against the actualist theory came from physicists, namely from W. Thomson (1824-1907), known as Lord Kelvin of Largs. His forty year long constant interest in the age of the Earth led him to challenge the chronological reckonings made by actualists. The issue of the age of the Earth became a crucial one not only for the relationship between science and the Bible, but also for that between physics and geology. It was a clash between two dating methods.
VI. The problem of the Age of the Earth
Biblical chronology was inadequate to account for the data which were being collected through geology and palaeontology. New evaluation methods were tested. One of the first calculations of the age of the Earth on an empirical-experimental basis is due to Buffon. Accepting that Earth took shape by cooling from a fused mass, in 1778 he reckoned 75000 years would be the time the Earth took to reach the present temperature. To avoid the criticism he underwent from the Sorbonne Theology Faculty at the time of the publication of the first volumes of his Histoire Naturelle, he started off by saying that the six days of Creation could not be taken literally (cf. Gohau, 1990, p. 199). Two of his contemporaries, the abbots and geologists Needham and Girault-Soulavie agreed with him, in fact the latter reckoned that the age of the Earth was over three million years. Endorsing a different view, Abbot Barruel denounced their "impiety" and abbot Maupied attacked those who did not take the Bible literally. This was the interpretation current at the time.
Cuvier and the other "catastrophists" had estimated "thousands of years." Scrope and Lyell had concluded that a very long time had been necessary for the erosion and the sedimentation of layers. The cyclical interpretation made this time virtually unlimited. Darwin (1859) tried to make an estimation of it, reckoning 300 million years had been the time necessary to strip an English region (Weald). J. Phillips, an Oxford geologist, in 1860 would obtain a much lower value for the development of the earthly crust as could be reckoned on the basis of the average sedimentation rate: 96 million years. In 1852 Lord Kelvin joined the debate with an article in which he argued that, if the Earth works as a thermal machine following Hutton's hypothesis, then it must lose energy over time, so that within a definite period the Earth would no longer be inhabitable. In 1862 he tackled the problem of the heat of the Sun, that he attributed to gravitational energy, and in 1863 the problem of the heat of the Earth and of its cooling over time, claiming some years later that the crust of the Earth could not remain as it is now, the whole Earth losing such a large quantity of heat over time. On the basis of different physical hypotheses, Kelvin estimated that the age of the Earth ranged between a minimum of 24 million years and a maximum of 400 million, 98 being the most likely value. The assumptions he took as his starting point were a challenge to Lyell's stationary view and also to the catastrophist theory, and appeared to support a "directionalist" theory. The values reckoned by him were too low especially for his theories of the evolution of the species, which had just been proposed by Darwin ( The Origin of Species, 1859), positing a much longer period. In 1868, addressing the Glasgow Geological Society, Kelvin congratulated geologists for breaking free of the Biblical conditioning in chronology, but he remarked they had exaggerated in their chronological estimations.
It was the beginning of a heated dispute between geologists and physicists on the most suitable dating systems, with mutual reproaches for ignoring one another's subject. Geologists worked out more independent reckoning techniques, based on the glacial theory, chemical dissolution of minerals, climatic changes, the saltiness of oceans, etc. From the whole set of data, though different, one would always deduce a definitely longer period than that proposed by Kelvin. To their aid came the pioneer of geophysics, Rev. O. Fisher (1817-1914) along with T.C. Chamberlin and F.R Moulton. The former (1881) claimed that there might be fluid masses inside the Earth, the latter (1899) gave rise to the Chamberlin-Moulton planetesimal hypothesis on the origin of the Earth (that is, the planets of the solar system were seen to arise from the rocks originating from an encounter between the sun and another star): in both cases Kelvin's calculations needed reviewing. Chamberlin observed that within atoms huge energies could be trapped. He was a good prophet: in 1896 Becquerel discovered radioactivity, though its importance for geology was only grasped in 1903, when Marie and Pierre Curie discovered that disintegration liberates heat. In 1904 Rutherford argued that the heat of the Earth might be attributed to radioactive elements, hence the Earth was not cooling down. Therefore Kelvin was wrong. The latter stood by his ideas and opposed the new views, invoking for heat an eternal source of energy.
In the years 1908-1910, R.J. Strutt had the merit of producing the first radioactive datings for a large number of minerals and of connecting them with stratigraphy. In 1913 A . Holmes (1890-1965) drew up the first complete account of the methods used to measure geological time, but it was only after 1917 that, thanks to a book by Y.J. Barrell (1869-1919), the geologists' scientific community accepted the new dating method. Over the years dating methods increased in number and analytical techniques became more precise; on the basis of Haughton's principle: "The correct relative measure of geological periods is the maximum thickness of the layers that have developed during these periods," the most important geological and biological events as well the duration of geological eras and periods were dated with a certain degree of reliability. Nowadays, the Earth is estimated to be approximately 4.5 billion years old, whereas the most ancient rocks date back to about 3.8 billion years ago. The age of the Universe ranges from 13 to 14 billion years.
VII. Some Aspects of the Comparison between Geology and Theology in the Contemporary Era
The dispute between geology and theology may be considered officially over with Lyell's work. Geology had won full independence and could move autonomously in carrying out its own research. It was also recognized that the Biblical account of the formation of the Earth did not mean to be a scientific description and hence it was enabled to regain its original intention, to be essentially a religious message. Since then, with Darwin, a much more heated debate would shift to the issue of the evolution of the species and of the origins of man.
While natural sciences moved with energy and enthusiasm on the path opened by the Darwinian theory, which, to judge from its fruits, turned out to be of great heuristic importance, theology initially struggled in the rearguard on the defensive side, with strong internal tensions. The grand theological system built over centuries of speculation posed the greatest problem, unable as it was to recuperate and to profit from other views that were equally available in the tradition of the Fathers of the Church and in Holy Scripture itself: it favored a view of reality that was static and "fixist," whereas the new sciences had adopted a dynamic and progressive conceptual framework. The view of an initial perfect creation had to be replaced by one in which limitations and evil appeared to be there from the start. A completely different mind frame was needed in a process which would involve more and more the notions of truth and nature. A deep and cool reflection was needed, on the one hand, on the specific contents and significance of the new theories, and on the other, on the foundations of faith. The conflict was tough, above all within the Christian Churches. Its negative effects and polemics continued throughout the 19th century in Great Britain, Italy, France and Germany. Numerous apologists arose, who may be roughly grouped into two categories: traditionalists (arguing that the Bible said the truth and science may not challenge it) and concordists (science could not but confirm the Bible). Against these two opposite views, defined "dangerous and lethal, equally contrary to the truth" by the Italian priest and geologist Antonio Stoppani (1824-1891), the well-known author of Il Bel Paese (1875), a number of scientists took action to bring the argument back onto the right path. In 1884 the Anglican Bishop F. Temple reminded "traditionalists" that "there is no more reason for setting aside Geology, because it does not agree in detail with Genesis, than there is for setting aside Astronomy because all through the Old Testament the sun is spoken of as going round the earth" (The Relations between Religion and Science, quoted by Pedersen, 1992, p. 83). In Italy, Stoppani himself felt the need to write in 1886 more than 400 pages in book titled Il dogma e le scienze positive, ossia la missione apologetica del clero nel moderno conflitto tra la Ragione e la Fede [Dogma and Positive Sciences, i.e. the Apologetic Mission of the Clergy in the Modern Conflict between Reason and Faith] to which he later added two dense volumes, posthumously published in Turin in 1893, L 'exemeron. Nuovo saggio di una esegesi della Storia della Creazione secondo la ragione e la fede [The Exemeron, A New Essay of an Exegesis of History according to Reason and Faith]. In these volumes the problem of the relationship between geology and theological thought was tackled in depth, with clarity of ideas, a very broad historical vision and plenty of details and data. It is no doubt, to works such as these that we owe a new theological attitude towards modern scientific thought.
Further attempts were also made to understand the theory of evolution correctly. By 1874, J.H. Newman (1801-1890), to whom we owe some enlightening statements on Christianity and Scientific Investigation (1855), could write to a bishop: "In the theory of evolution I see nothing incompatible with an Omnipotent and a Provident Creator." The most systematic and the best known attempt was made by Teilhard de Chardin (1881-1955), who, taking as his starting point his own work as a scientist, incorporated the new perspective of evolution into his philosophical and theological reflection. There is, however, a small, but dynamic minority, of believers, generally belonging to some Christian Evangelical and Reformed Churches, who continue to defend the traditionalist view of creation and the Flood, above all in the United States.
The magisterium of the Catholic Church, leaving it to theological reflection to analyze in depth in what way Revelation could be harmonised with scientific data, had gradually offered clarifications of the issue. In his 1893 Encyclical Providentissimus Deus Leo XIII affirmed that the Bible would not claim to teach earthly sciences. In 1909 a declaration of the Pontifical Biblical Commission , during the pontificate of St. Pio X, had made clear that the word "day" (hebr. jôm ) featured in the first chapter of the Book of Genesis should not be taken in literal terms (cf. DH 3519) and, more importantly, it had given a negative answer to the question whether in that very same narrative "it was necessary to look always and thoroughly for the qualities of scientific language" (cf. DH 3518). First Pope Pius XII (cf. Humani generis , 1950, DH 3896) and then more explicitly Pope John Paul II (cf. Message to the Pontifical Academy of Sciences, 22.10.1996, in Papal Addresses, 2003, pp. 370-374, original French text in OR 24.10.1996, pp. 6-7) indicated in what way, first the "hypothesis" and later the definitive "theory" of evolution did not contradict the Biblical message. In his Catechesis on Creation, talking of the Biblical text on Creation and the scientific consequences (including datings) which we could wish to draw from it, John Paul II had already pointed out in 1986 that "this text has a religious and theological importance. It does not contain significant elements from the point of view of the natural sciences. Research on the origin and development of the individual species in nature does not find in this description any definitive norm or positive contributions of substantial interest. Indeed, the theory of natural evolution, understood in a sense that does not exclude divine causality, is not in principle opposed to the truth about the creation of the visible world, as presented in the Book of Genesis." (General Audience, 29.1.1986, n. 3).
It remains true, however, that the issue of the scientific origin of the Earth has many philosophical, ethical, as well as theological implications. The difficult process of analyzing and reviewing theological formulations, as certain aspects would demand, is as yet far from being concluded. The fact that even at the time when the debate on the results of geology started, numerous believers and also members of the clergy engaged in science -Spallanzani, Stoppani, Borson, Secchi and Denza in Italy, the English geologists J. Playfair, O. Fisher, A. Sedgwick, W. Buckland, C. Kingsley and J. Blake, an later the French paleontologist Teilhard de Chardin, just to mention a few scholars- is a positive sign pointing in the direction of a peaceful solution of the conflict, which may still be valid nowadays.
As for earth sciences, over the last decades they have been making great progress marked by important discoveries. New theories have arisen: continent drift, plate tectonics, as an expression of the "dynamical" view of continental masses, which gained acceptance around 1970. The great times introduced by radiometrical datings gave new life to Lyell's actualism, which seemed to dominate unrivalled. And yet, over the last years, space voyages, the new frontiers of cosmology, the discovery of generalized extinctions of old biological species led to the formulation of "neocatastrophism" (cf. O.H. Schindewolf, Neokatastrophismus?, 1963, quoted by Albritton, 1989, p. 175). Various geological phenomena still remain unexplained, and the debate then remains open to new contributions and to new syntheses.
An interesting case in question is the "Gaia Hypothesis" formulated in the 1970s by the chemist James Lovelock (Gaia. A New Look at Life on Earth, 1979; The Ages of Gaia. A Biography of Our Living Earth, 1988; Homage to Gaia. The Life of an Independent Scientist, 2000). While carrying out some research commissioned by NASA in view of designing instruments for discovering any existing life forms on Mars, he came to formulate the idea that the Earth is a living system capable of self-organization. The Earth, that is, is not to be seen as a dead planet, made of rocks, oceans and atmosphere, but as a "system embracing all its life and all its environment strictly bound together, in such a way as to form a self-regulating entity." This hypothesis was called Gaia, after the name of the Earth goddess venerated in Pre-Hellenic Greece. The idea was not entirely new: Hutton had already advocated a chained sequence of geological and biological processes and had compared the circulation of earthly waters with that of blood (Hutton was also a physician). Analogously, the naturalist A. von Humboldt (1769-1859) had referred to the terrestrial globe as to "a great compound, an organised body." The Gaia hypothesis was met and is still met with a certain resistance amongst academics, both because it involves and requires competence in more than one discipline (geology, microbiology, geochemistry, atmospheric chemistry), and because by some it is considered teleological. It would seem to imply the intentional character of natural processes, even though, by improperly affirming a certain personification of nature expressing itself as a living body, it simply highlights some self-adjustment and homeostatic processes at various levels.
Whether or not the Gaia hypothesis is valid, the message it conveys is clear: science has now reached such a level of specialisation that each autonomous discipline can only grasp a small part of reality: if we wish to reach a larger portion of reality and find a meaning for the whole, it is necessary to take into full account the complexity of reality, to rise above the fragmentation of disciplines and to tend to their assimilation into a broader vision. This attitude is not unknown to some interdisciplinary incentives coming from the Anthropic Principle.
VIII. Concluding Remarks.
At the end of this mainly historical outline, we propose some concluding remarks.
Human beings have always felt the desire, or rather the need to understand themselves, life and the world around them. They have this need, as they need oxygen to breathe or food to live. There is no culture that has not tackled and solved this problem in some way or other. The earliest solutions proposed were based on myth, on poetry, and had a unifying character: the human being felt part of a whole, filled with life and peopled by gods, spirits, gnomes, nymphs; nature is the free playing field of these whimsical forces, which man may allure by sacrifices, gift, magic acts. Apart from the contents of the various beliefs, their meaning is clear: in their relationship with nature, human beings recognize their contingency and dependence on a Reality that transcends them. The development of rational thought then determined a different attitude towards nature which gradually lost its driving and animate character to become more and more the focus of an objective study: Christianity would make a significant contribution to this process, but from the Modern Age onwards, especially with Descartes' mechanicalist view, the human being himself would become the object of a disenchanted study.
As far as the meeting between Christian Revelation and the rise of scientific thought is concerned, the Biblical account of the origins, as is handed on by the Book of Genesis (narratives of Creation and the Flood), worked as a theory --though it is not a scientific theory in the proper sense of the word. This was apparent in the 17th century, when the naturalistic sense began to gain ground: the Biblical account not only looked a consistent and ultimately satisfactory view of the world as was known then, but it also stimulated and guided research. Scientists were persuaded of the veracity of the Biblical text and looked for confirmations in nature. But this theory differs from any other in being part of the sacred text, inspired by God, and it is then easy to understand the obstinate defence of this view by all those who gave a literal interpretation of it. The complication arose from the fact that the earliest geological research work was done on sedimentary structures, that is on deposits originating in a watery environment, and seemed to match the Genesis narratives quite well. The triggering factor for the crisis of trust in the Biblical text would be the awareness of time length. This was the result of the study of sedimentary structures and of fossils. The periods of time the Bible refers to (forty days of torrential rains followed by a hundred and fifty for the withdrawal of waters) could not have sufficed for the huge variety of phenomena that were being discovered to have all taken place. Yet, at least initially, there were no direct proofs, but only glimpses.
The continuing debate showed how natural scientists might be divided into two groups: those operating independently of the Biblical tradition and those trying to save it, by reinterpreting it. The latter proceeded just like any scientist pursuing the theory he or she believes in. Thus the six days of Creation were considered to be as many periods of indefinite length, hence the period going from Creation to the Flood may be lengthened at leisure, so as to account for the phenomena observed. This is the concordist system, a way of wilfully harmonizing science and faith at all costs, which is now less prevalent than in the past, but the temptation is still as strong for the believer.
An overview of many centuries of dialogue between theology and geology (and, more generally, science), makes it clear that the human being has never been fully satisfied with partial knowledge and has constantly striven to acquire a comprehensive and exhaustive kind of knowledge. Starting from personal experience, though limited, based on a number of observations and experiments, human beings have a tendency to generalize, in an attempt to embrace all phenomena and to predict them. It is the power of human intelligence and creativity, at the service of desire (or the need) for wholeness. This kind of procedure is clear in Werner, Hutton, Lyell, to focus just on geologists. Werner built his theory on observations concerning the Saxony region and the surrounding areas, Hutton on the rocky structures of Scotland. Lyell's own field of investigation was broader, for he supplemented it with studies of the Parisian sedimentary deposit and the volcanic structures in Auvergne and Italy. For these reasons their theories could not be universally applicable and would later be revised, updated and supplemented.
The role of reasoning by analogy and hypothesis is greater in earth sciences than in physics or chemistry, because geologists examine irreversible phenomena of the past on the basis of the present order of things. It may be compared to a great thriller, in which from scattered clues the whole matter has to be logically and coherently reconstructed. Testing may only be used by analogy, allowing for certain specific conditions. Confirmation can only be indirect. The role of theory, though weak and limited, is in any case essential to develop a science. History prefers to remember those who drew up theories much more than those who tested them, whose role is all the same fundamental for data collection. This is because a theory is first of all unifying, inasmuch as it provides an interpretation of those data and observations; then it claims and has to be predictive and heuristic, providing stimuli for investigation. It is in this sense that we hinted above at the Biblical view as a (non-scientific) theory.
In formulating a theory, often aesthetic or ethical points of view, philosophical or religious insights, that is extra-scientific factors, play a major role. Think of how Aristotle's thought came under the spell of the geometrical figure of the circle and the consequences it produced! A key point of Hutton's view, for instance, is that the Earth is not a machine, but an "organized body," whose goal is to keep being inhabitable. Such finalist considerations fill Huttonian texts: "This globe of earth is obviously made for man." Hutton was moved by great piety and faith in the Author of nature. As we said, Hutton rejected catastrophism as unworthy of the divine blueprint. His epistemology, furthermore, distrusted any experiment designed outside a theoretical framework, since he held that philosophy or general knowledge alone were suited to guide a meaningful experiment (cf. Laudan, 1987, p. 126). Lyell also shared with Hutton the idea of the existence of a divine plan: he was persuaded that all geological facts, no matter the distance in time they have from the present, are part of a single interconnected plan. All of them proceed from the same Author, and they are indelibly marked with the traces planned by One Mind (cf. Klaver, 1997, p. 23). His science was centered religiously around anthropocentric principles. It has been argued that Lyell took on board Hutton's actualist principle because he too was a deist and, like Hutton, he saw in the world a reflection of the ordering wisdom of the Author of life and believed in the privileged position of the human being in the cosmos (cf. Laudan, 1987, p. 202). Philosophical and moral, as well as scientific considerations were responsible for delaying until late in life Lyell's acceptance of Darwin's evolution theory, which to him amounted to an attack on human dignity (cf. Klaver, 1997, p. 67): the difference between the human species and the others is of quality, not of degree.
Scientists of past times were moved by a profound conviction, be it religious or philosophical, about the rationality and intelligibility of reality. Such a conviction drove them to search for truth, acknowledged and declared as the true meaning of any scientific work. Nowadays the human being is seized by a sense of bewilderment in front of the unfathomable vastness of time and space as they have been opened up by earth science and cosmology as well as by the repeated life and death cycles in succession through the ages as claimed by palaeontology. This sense of confusion becomes dismay in front of future prospects, for no reassurance is available. According to the French geologist and historian F. Ellenberger, modern man is as afraid as his forefathers to border on the unknown.
But, then, should we trust S. Weinberg, Nobel laureate for physics in 1979, who ended his book, The First Three Minutes (1977), with the words "The more the universe seems comprehensible, the more it seems pointless"? How do you get out of it? Is it only through research, hence turning the means into an end? Weinberg indeed adds: "But if there is no solace in the fruits of our research, there is at least some consolation in the research itself. [...] The effort to understand the universe is one of the very few things that lifts human life a little above the level of farce, and gives it some of the grace of tragedy."
Weinberg's final sentence --as a form of elitist consolation for radical pessimism-- is the epitome we find in a geology textbook written by a brilliant Italian geologist (cf. F. Ricci Lucchi, La scienza di Gaia, Bologna 1996). The very fact that a geologist should refer to a physicist's reflections to express the existential distress produced by progress in scientific knowledge shows how such a distress is not limited to a subject area, but it is common to all. This distress though is rooted in motivations falling outside the scope of science, and may be overcome exclusively with the support of philosophical or religious inclinations. Science intends to be, and in fact is a rational description of reality; it raises questions, poses problems, but does not claim to be able to find or to disclose the meaning of life and of the universe. The sense of bewilderment seizing us strangely echoes a distant question raised by the Psalmist: "When I see your heavens, the work of your fingers, the moon and stars that you set in place, what are humans that you are mindful of them, mere mortals that you care for them?" (Ps 8:4-5). The Psalmist though believed in the meaning of life because he believed in God and by setting such questions he meant to express his amazement that the human being should be the focus of so much attention and loving care. This belief relied on a different reading of things, which was not grounded on scientific discoveries, a reading which may still be valid for, and thus be adopted by us, in our days over two thousand years later.
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