![]() ![]() Jordan/Understanding Earth, 6th ed., adapted by T. But cratons aren’t so dense, possibly because a period of melting removed heavier constituents such as iron. Typically such cooling would make a rock more dense, and it would drop below sea level. ![]() WHAT LIES BELOW | Cratonic crust is cooler and stronger than oceanic crust. QUICK COMPARISON Craton lithosphere differs dramatically from oceanic lithosphere when it comes to such factors as depth and mineral composition. The map above shows the names and global distribution of cratons dating back to the Archean, more than 2.5 billion years ago. STABLE CENTERS | Cratons lie in the interiors of continents, largely undisturbed by processes of uplift, subduction and rock recycling occurring around them. New Moon/Panoramic ImagesĪ sample of gem-studded cratonic rock from South Africa. Yellowstone National Park sits on the edge of the Wyoming craton, which extends through the west-central United States. For him, the more flexible expanses of crust he called orogens, full of rising mountains and earthquake faults, were where the action was. When Viennese geologist Leopold Kober gave geology a new word - kratogen, soon shortened to craton - for the flat, stony interiors of continents, he thought such places to be among the duller places for geological study. ![]()
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