6 Pages in Charles Darwin's Library associated with "strata/epochs - chalk"

Lake Superior: its character, vegetation, and animals, compared with those of other similar regions
By: Agassiz, Louis,
Publication info: Boston, Gould, Kendall & Lincoln, 1850
Pages: Page 258 Page 285 End Slip 2, side 2 End Slip 2, side 2
A manual of elementary geology
By: Lyell, Charles, Sir,
Publication info: [s.n.], [s.n.], 1855
Pages: Page 251 Page 350