<P> Daphne Major is a volcanic island just north of Santa Cruz Island and just west of the Baltra Airport in the Archipelago of Colón, commonly known as the Galápagos Islands . It consists of a tuff crater, devoid of trees, whose rim rises 120 m (394 ft) above the sea . </P> <P> Though easily accessible to most visitors to the Galápagos, the national park service has highly restricted visits to this island, and it is primarily used for scientific research . An intensive study of Darwin's finches was conducted here by biologists Peter and Rosemary Grant over a period of 20 years . They examined the behaviour and life cycles of finches, with the results strongly supporting Darwin's theory of evolution . Their efforts were documented in the Pulitzer Prize--winning book The Beak of the Finch . </P>

Why is daphne major such a good island for studying finch evolution