The chief work of his life was , however , in geology .
He has been designated by Jules Marcou as the founder of American Paleozoic stratigraphy , and the first discoverer of the primordial fauna in any country .
The chief work of his life was , however , in geology , and he has been designated by Jules Marcou as the founder of American Paleozoic stratigraphy , and the first discoverer of the primordial fauna in any country .