Life and Death of Coral Reefs : Springer : 9780412035418 : 0412035413 : 31 Jan 1997 : Charles Birkeland Living coral is a thin veneer, measured in millimeters. Yet this thin film of living tissue has shaped the face of the Earth by creating limestone structures sometimes over 1,300 m thick from the surface down to its base on volcanic rock (Enewetak Atoll), or over 2,000 km long (Great Barrier Reef). About half the world's coastlines are in the tropics and about a third of the tropical coastlines are made of coral reef. Archipelagoes of hundreds of atolls such as the Marshalls, the Maldives, the Tuamotus, and most of the Carolines and Kiribati have been fonned by coral. In addition to enlarging high islands (such as the entire northern end of Guam) and extending and protecting coastlines, ancient biogenic reefs have fonned even larger areas on the present continents. Shallow living coral 2 reefs are estimated to presently cover over 600,000 km (Smith, 1978). Coral reefs are dynamic sys