State of the art in the mid-late 1800s, by Charles Lyell, the advocat of geology, an idealized section of the earth's crust. https://jamescungureanu.wordpress.com/2015/01/03/visions-of-science-charles-lyell/
Lawyer & Gelogist Charles Lyell (1797-1875)
Charles Lyell - author of Principals of Geology, one of the books Alma had read relating to her work with moss.
Sir Charles Lyell sketch of a land slip.
Principles of Geology, by Charles Lyell
"A Manual of Elementary Geology" by Sir Charles Lyell (5th ed.,1855)
Sir Charles Lyell, 1st Bt, 1883, by Lowes Cato Dickinson
Principles of Geology, by Charles Lyell, at American Buddha Online Library
Darwin's notes stating, "If this were true adios theory" from page 442 from Charles Lyell's Principles of Geology Vol. 2.