Geology and petrography of volcanic rocks of the Truk Islands, East Caroline Islands

The Truk Islands are a near-atoll in the North Pacific Ocean at about 720' north latitude and 151 east longitude. They consist of 12 volcanic islands and many low coral reef islands in a lagoon approximately 30 by 40 miles, enclosed by a coral reef. The volcanic islands range from 5 by 2 miles to islands less than a quarter of a mile in diameter. Several peaks on the volcanic islands rise more than 1,000 feet; the highest altitude is 1,453 feet, on Tol. Dense, jungle vegetation covers slopes and crests of the volcanic islands and many of the reef islands.