Digitized content includes three engraved illustrations. Figure 22, Dwarf's Tower (Zwergli-Thurm) near Viesch in the canton of Valais. From a sketch by Lady Lyell, taken September 1857, Figure 23, Ravine on the farm of Pomona, near Milledgeville, Georgia, as it appeared January 1846, and Figure 47 View of the Axmouth landslip from Great Bindon, looking westward to the Sidmouth hills, and estuary of the Exe. From an original drawing by Mrs. Buckland.

Principles of Geology, by Scottish geologist Sir Charles Lyell (1797-1875) was first published in 3 volumes from 1830–1833. Lyell used the theory of uniformitarianism, the assumption that the same natural laws and processes that operate in our present-day scientific observations have always operated in the universe in the past and apply everywhere in the universe, to describe how the Earth's surface was changing over time