Final answer:
Charles Lyell's work on geology and the ancient age of Earth influenced Darwin's understanding of sedimentary rocks and evolution.
Step-by-step explanation:
The historical scientific figure who helped Charles Darwin understand the significance of the layers of sedimentary rocks for evolution was Charles Lyell. Lyell, a prominent English geologist, authored 'Principles of Geology,' which argued for gradual geological processes shaping Earth's surface and suggested a much older Earth than previously thought. This notion of a more ancient Earth provided Darwin with the timeframe necessary for evolutionary processes to produce the observed diversity of life.