Geology is eminently an out-door science; for strata, rivers, oceans, mountains, valleys, volcanoes, cannot be taken into a recitation room. Sketches and sections serve a good purpose in illustrating the objects of which the science treats, but they do not set aside the necessity of seeing the objects themselves.

The Geological Story Briefly Told, Prefatory Suggestions (p. 6), American Book Co. 1895