
letter to Mrs. Ezra S. Carr (December 1872); published as " A Geologist's Winter Walk http://books.google.com/books?id=OAEbAAAAYAAJ&pg=PA355", Overland Monthly, volume 10, number 4 (April 1873) pages 355-358 (at page 358); modified slightly and reprinted in Steep Trails (1918), chapter 2
1870s