Insular Geology of the Line Islands

Abstract

The Line Islands seamount chain consists of a series of ridges and seamounts which extend 4800 km across the Central Pacific Basin (Fig. 1). The seamounts form the longest intraplate submarine mountain chain in any ocean, rising from a sea floor in excess of 5000 m deep. Only twelve seamounts reach sea level to form low islands or atolls; all are presently bordered by fringing reefs. Some seamounts extend above sea level to form typical atolls, having shallow salty lagoons and a rim occasionally broken by channels to the sea, e.g., Fanning, Palmyra and Caroline. Still other seamounts reach sea level and form islands with unbroken land surfaces, e.g., Jarvis, Vostok and Flint Islands. All of the islands are low and nearly flat. Christmas Island and Johnston Island display the highest elevations with sand dunes reaching 12 m.