of the sun. Like Kant, he underlined how much he and his contemporaries did not know, writing in 1749, ‘There are many parts of the surface of the globe with which we are entirely unacquainted, and have but partial ideas of the bottom of the sea, which in many places we have not been able to fathom.’ Men had only been able to explore ‘the mantle of the earth’ since ‘the greatest caverns and the deepest mines do not descend above the eight thousandth part of its diameter’.5
Buffon did, however, consider that the earth was a solid, homogeneous globe, not hollow or empty. He theorized that the planet was initially a molten mass that had gradually solidified (see above, chapter 2) and filled with a vitreous material of roughly equal density to sand. He rejected the hypothesis that the core was still on fire. The thinking of later generations was led by geological and physical observations, and the question of the earth’s inner structure was set aside for a while. Late-eighteenth-century scholars seemed tacitly to agree that the earth’s interior was unknowable, focusing their attention instead on visible phenomena such as geological strata, mountains and volcanoes.
For a period of nearly eighty years, from 1750 to 1830, the main focus of early geologists was developing mineralogy to further their knowledge of the nature of rocks and observing stratigraphy and mineral fossils to identify the successive geological eras that left their mark on the surface of the globe. At this point, it is useful to take a brief look back at a scholar whose work proved far-sighted, though it received little notice in his lifetime. Nicolaus Steno was the founding father of stratigraphy and tectonics and identified the organic origin of fossils, realizing that they were the remains of species now extinct. Decades ahead of his time, he pointed out that strata, or layers of sediment, built up as a result of successive deposits in a liquid environment. He hypothesized that the order of deposits must reflect the order of episodes of global history and that where strata were no longer horizontal, it must mean the earth’s crust had moved vertically at some point. Steno founded modern geology a century before other thinkers caught up, but his writings drew little attention and his ideas had little impact on the history of knowledge – and of ignorance.
As shown in chapter 2, one of the two vital issues in filling in the scientific map was the full acceptance of extremely longue durée geological timescales in the 1760s and 1770s. The observation of strata now meant that geology became a historical source. This new understanding of the geological past challenged the views of Flood geologists; in the nineteenth century, the argument pitted catastrophists against uniformitarians (see below, chapter 13).
Part I of my book will focus solely on the rise of geology through ever more detailed studies of the earth’s surface and visible morphology, collecting evidence for the ‘constitution and conditions of the depths’.6 The debate on representations of the earth in the closing years of the eighteenth century and first half of the nineteenth turned on two main questions. The first was whether tilted strata of sedimentary rocks arose from the way the deposits formed as they were laid down, or whether they bore the traces of fractures from vertical and horizontal tectonic movements, as argued by those who had studied mountain ranges closely. The second, much more heated debate pitted the Neptunists, led by Abraham Gottlob Werner, against the Plutonists, who followed James Hutton. The two scholars studied rocks with a view to ‘identifying, differentiating, and giving precise descriptions of the various minerals and rocks that make up the Earth’s surface’.7 Their ambition was to ‘describe the visible surface of the Earth as objectively as possible and to identify its principal components’.8
Werner’s and Hutton’s theories – and their followers – were radically opposed. Werner’s Neptunism, which dominated the closing quarter of the eighteenth century, posited that water caused sedimentary deposits. All minerals and rocks, including, most polemically, basalt, were initially ‘in a dissolved state at the bottom of the primeval ocean’. Werner, somewhat influenced by diluvial theory, argued that the various strata were deposited in turn as they filtered out of the water. At the end of the eighteenth century, Werner still believed that water played a fundamental role in creating the earth. Vincent Deparis rightly points out that the theory did at least encourage detailed examination of the various layers of sediment.
In 1778, however, Déodat de Dolomieu concluded from his study of basaltic lava that it could only come from the interior of the earth as a viscous flow, contradicting Werner’s Neptunism. This led to a lively scholarly argument. In 1785, James Hutton joined in the attack on Neptunism, making the case that the earth’s inner core was still burning. The heat rising from the subterranean regions was what forced rocks upwards as the cycle of sedimentation continued. This Plutonist theory accounted better than Werner’s Neptunism for the very long timescales of the geological past, which many scholars now believed in. Plutonism also had the advantage of accounting for something that was obvious to even the most casual observer: the interior of the earth was still full of fiery matter.
Neptunism dominated scholarly debate until around 1795. Vincent Deparis records a swift change of opinion between 1802 and 1804, at the very end of the period, when studies of the volcanoes of the Auvergne swayed the debate towards Plutonism.
How, then, did early-nineteenth-century Europeans building on Enlightenment science picture the earth, understand its surface and its reliefs and imagine its past? It is difficult to give hard and fast answers, but we can put forward some hypotheses.
It seems likely that most of the population, spending their lives within a very small geographical scope, wasted little or no time worrying about such matters. Their lack of knowledge about far-flung regions – and for most people, even ones closer to home – meant that towns, plains, hills and even the mountains that closed off their horizons were simply features of the earth, as mentioned by the priest in the pulpit preaching from the Book of Genesis. That would certainly have been enough to satisfy the curiosity of those few who did wonder about the past and the shape of the earth, which was to be admired as God’s creation. The Flood was generally accepted as historical fact and some might have thought that it was bound to have shaped the planet as they saw it. Almanacs, which were practically the only reading matter available for many people, barely touched on such questions.
Yet the stratification of ignorance was already beginning to grow more complex: amateurs with a passion for science were starting to gather in academies in the provinces, Paris and London, and reading accounts of papers given at scholarly institutions and the books published by their members. They were also able to keep abreast of the latest developments in gazettes. The members of such institutions at the turn of the century were doubtless curious about the history of the earth, what its interior was made of and how it had been shaped. However, it is difficult to measure the extent of this scientific elite and to find out whether artists, writers and political leaders asked the same questions.
Working on the hypothesis that they most likely did, they must have been very confused by the clashing theories, incomplete experiments and inaccurate observations made by the scientists of the day! It is, however, fair to say that unlike half a century previously, most of the elite would now have been relatively comfortable with stepping back from the Biblical narrative and understanding that the earth’s morphology reflected a history that was hundreds of millennia old. This was a fundamental stage in overturning earlier representations of the earth.
For early-nineteenth-century thinkers, sedimentary strata and the potential for horizontal and vertical movement, whether driven by water or by fire, and the nature of the fossils entombed in them must have made up a somewhat incoherent data set that would have been difficult to take as the basis for a clear picture of the planet they lived on. It should also be borne in mind that what we now know of glacial reliefs and multiple successive periods of glaciation was at that point wholly unknown, and that mountaineering and mountain exploration were in their infancy. Doubtless the most cultivated travellers – a group we will return to later – were
