Darwin observed marine fossils in the mountains and the uplift of land by an earthquake which supports Lyell's theory.
Explanation:
Lyell's theory of an ancient Earth states "the formation of Earth's crust took place through countless small changes occurring over vast periods of time".
So Darwin had an observation of marine fossils that uplifted the land through many years by earthquake. Which was the same thing Lyell's explained.
According to known natural laws, It takes lots of time to form the earth's crust.
