Chapter V.--Curious pumiceous infusorial mudstone (page 118) of

Patagonia; climate of old Tertiary period, page 134. The subject which has been most fertile in my mind is the discussion from page 135 to end of chapter on the accumulation of fossiliferous deposits. (556/3. The last section of Chapter V. treats of "the Absence of extensive modern Conchiferous Deposits in South America; and on the contemporaneousness of the older Tertiary Deposits at distant points being due to contemporaneous movements of subsidence." Darwin expresses the view that "the earth's surface oscillates up and down; and...during the elevatory movements there is but a small chance of durable fossiliferous deposits accumulating" (loc. cit., page 139).)