He observed that fossils appear first in "transition" or palaeozoic strata, and were mainly corals and molluscs; that in the older carboniferous rocks the fossils are of higher types, such as fish and amphibious animals; while in the tertiary or alluvial strata occur the remains of birds and quadrupeds.

He thought that marine plants were more ancient than land plants.

His studies led him to infer that the fossils contained in the oldest rocks are very different from any of the species of the present time; that the newer the formation, the more do the remains approach in form to the organic beings of the present creation, and that in the very latest formations, fossil remains of species now existing occur.
Such advanced views as these would seem to entitle Werner to rank as one of the founders of palaeontology.[73] Hutton's _Theory of the Earth_ appeared in 1785, and in a more developed state, as a separate work, in 1795.[74] "The ruins of an older world," he said, "are visible in the present structure of our planet, and the strata which now compose our continents have been once beneath the sea, and were formed out of the waste of preexisting continents.

The same forces are still destroying, by chemical decomposition or mechanical violence, even the hardest rocks, and transporting the materials to the sea, where they are spread out and form strata analogous to those of more ancient date.

Although loosely deposited along the bottom of the ocean, they became afterwards altered and consolidated by volcanic heat, and were then heaved up, fractured, and contorted." Again he said: "In the economy of the world I can find no traces of a beginning, no prospect of an end." As Lyell remarks: "Hutton imagined that the continents were first gradually destroyed by aqueous degradation, and when their ruins had furnished materials for new continents, they were upheaved by violent convulsions.