 He explored the geology of the area, reaching conclusions about slate formation and the injection of granite seams as liquid which differed from the ideas of Lyell and Sedgwick.The zoologist Andrew Smith showed him formations, and later discussed the large animals living on sparse vegetation, showing that a lack of luxuriant vegetation did not explain the extinction of the giant creatures in South America.Around 15 June Darwin and FitzRoy visited the noted astronomer Sir John Herschel.