4 Pages in Charles Darwin's Library associated with "strata/epochs - silurian, upper"

A manual of elementary geology
By: Lyell, Charles, Sir,
Publication info: [s.n.], [s.n.], 1855
Pages: Page 446 Page 447 Page 457
Supplement to the fifth edition of A manual of elementary geology
By: Lyell, Charles, Sir,
Publication info: London, John Murray, 1857
Pages: Page 30