“Ideal section of part of the Earth’s crust,” from Elements of Geology, by Charles Lyell, 1857 CE.
“Ideal section of part of the Earth’s crust explaining the theory of the contemporaneous origin of the four great classes of rocks,” frontispiece of Charles Lyell, Elements of Geology, vol. 1. (New York: Appleton, 1857).
Charles Lyell (1797-1875) was one of the most influential geologists of the 19th century, and a personal friend to Darwin. In contrast to the ‘catastrophism’ of other geologists, Lyell’s ‘uniformitarianism’ argued that the features of the earth were a result of slow, gradual, and directionless forces of change that continued to operate in the present day. This image illustrates the principle as it relates to the different kinds of rock, differentiated over time through forces like erosion, pressure, and heat.
Image via Wikimedia Commons; full text through Googlebooks.