Fossils were often considered excellent evidence of Noah's Flood, and in the 18th cy., Voltaire tried to debunk them.
https://decapoda.nhm.org/pdfs/33537/33537.pdf
Some other theories in early modern times was that fossils were God's doodlings on the rocks, or else that they somehow emerged from the rocks themselves.
A notable advocate of the divine-doodling theory was
Johann Beringer (1670-1738) but many of the fossils that he worked from were fakes created by two of his colleagues to embarrass him:
Beringer's Lying Stones
Another early geologist was
Nicolas Steno (1638-1686) someone who worked out principles of stratigraphy, principles for interpreting the layering of rocks on our planet's surface.
Giovanni Arduino (geologist) (1714-1795) did the first identification of geological strata, naming them Primary, Secondary, Tertiary, and Quaternary (1, 2, 3, 4).
William Smith (geologist) (1769-1839) prepared some of the first geological maps ever, traveling around Great Britain and recording what kinds of rock he founds. He became known as "Strata Smith" for recognizing that the rocks came in neat layers or strata.
Later geologists built on his work, mapping other places, and dividing up geological time by characteristic strata and fossils.
Georges-Louis Leclerc, Comte de Buffon (1707-1788) proposed that the Earth was some 75,000 years old, though he was made to recant anything that seemed contrary to the Book of Genesis. He also proposed "centers of creation", different spots where the ancestors of organisms were poofed into existence. Thus, deer were poofed into existence in Eurasia and North America, and kangaroos in Australia.
Georges Cuvier (1769-1832) did a breakthrough that many of us may consider very surprising. He convincingly demonstrated that some species had gone extinct. He looked at mammoth bones, and while mammoths are obviously some species of elephants, they were different enough from present-day species to be their own species. But he noted that nobody has ever found a living mammoth, despite the animals being as big as present-day elephants. So mammoths have gone extinct.
That was a conceptual breakthrough, since there was a widespread belief back then God would not allow any of his creations to go extinct.
He also proposed that extinctions were caused by geological catastrophes, and that was a popular theory in early 19th cy. geology. It was discredited as a superfluous hypothesis by the mid 19th cy., with uniformitarianism triumphing. It was notably advocated by
Charles Lyell (1797-1875), and for a long time, geologists were very reluctant to accept the existence of anything much more catastrophic than anything well-documented. That changed over the last century, as geologists' techniques improved. Nowadays, we recognize both uniform and catastrophic causes, and treat them as hypotheses to be tested.
Early 19th cy. geologists often believed in multiple special creations over geological time: poof-poof-poof-poof-poof. Much like what old-earth creationist Hugh Ross believes.
In the 18th and early 19th cys., geologists argued over these hypotheses:
- Neptunism - rocks formed from sedimentary deposits and crystallization in the Earth's oceans.
- Plutonism - rocks formed from glowing hot material from the Earth's interior.
They were both partially correct -- sedimentary rocks are what the neptunists were right about, and igneous rocks are what the plutonists were right about.
Some neptunists claimed that basalt layers in rocks were sedimentary, condensed out of water, but that was stretching it. Rock basalt closely resembled volcanic basalt: both are crystalline and neither has fossils in it. Also, basalt is sometimes intrusive in other rocks. So it is evident that rock-layer basalt is as igneous as volcanic basalt.
