26 September 1997
Vol 277, Issue 5334

About The Cover

The topographic relief of the Indian Ocean floor and surrounding continents ranges from ~8 km above sea level [the Himalayas (red to lavender), upper right] to ~7 km below it [the Java Trench south of Sumatra (dark purple), right edge]. Combining satellite gravity data with ship depth soundings reveals the plate tectonic fabric of the sea floor in detail. Variations in the increase in depth away from mid-ocean ridges (greens) suggests a complex pattern of heat loss from Earth. See 1956 and the News story on 1921. [Image: W. H. F. Smith]