Volcanoes are cracks in Earth's crust that allow molten rock and hot gases to escape. According to the U.S. Geological Survey (USGS), there are about 1,350 volcanoes worldwide that have the ...

Giant regions of the mantle where seismic waves slow down may have formed from subducted ocean crust, a new study finds.

By dragging huge chunks of crust into the mantle ... Others believe only single-celled organisms reigned when Earth's plates first cracked apart. In fact, as new methods allow scientists to ...

They suggested that as new sea-floor crust was formed around ... new sea floor is created along a crack that follows the crest of midocean ridges. In 1966, earth scientists first identified ...