The proterozoic ophiolite problem, continental emergence, and the venus connection.

To account for the lack of preservation of ophiolites (fragments of oceanic crust and mantle) in old orogenic belts (age 1000 to 2500 million years), a hypothesis proposes that the magmatic oceanic crust formed during sea-floor spreading was thicker during the cited time interval. This thickening led to reduced contrast between the elevation of continental and oceanic regions and to greater average flooding of the continents. The resultant distribution of elevation may have resembled modern Venus more than modern Earth.