 As a fifth topic, in chapter ten, Darwin developed his position on the fossil record. At issue was whether the known fossil record displays a gradual progression of forms from simple to complex, as might be argued by Lamarckian transformists, or whether it supported the claim for the persistence of major groups throughout the record as might be held by someone endorsing the tradition of Cuvier (see the entry on  evolutionary thought before Darwin,  Section 4.1). The thesis of geological progressionism had in fact been denied by none other than Darwin’s great mentor in geology, Charles Lyell in his Principles of Geology (1830–33; Desmond 1984; Bowler 1976). Darwin defended the progressionist view in this chapter.