“When you start naming geologic-time terms, you need to define what exactly the boundary is, where it appears in the rock strata,” says Whitney Autin, a stratigrapher at the SUNY College of ...

Beneath Yellowstone lies a magma reservoir, pulsing with molten and superheated rock and exsolved gases. Scientists have long ...

It is believed that a 480 by 240 kilometer section of the underground mantle formed large-scale rock strata for a depth of 8 kilometers two billion years ago. Layers of solid bedrock at the ...

Thus, any deformations of strata (Figures 2 and 3) must have occurred after the rock was deposited. The principle of superposition builds on the principle of original horizontality. The principle ...

Smith's colourful and sophisticated geological map was based on his astute observation that rock layers (strata) could be identified by the fossils they contain. He noticed that the layers always ...