The basalt which makes up the Giant’s causeway is an igneous rock. Sedimentary rocks are formed by small rock pieces which are transported by rivers and laid down in layers. Chalk is a ...

Mudrocks, mudstone, and shale comprise about 65% of all sedimentary rocks. Glacial till is unsorted sediment deposited directly by glacial ice. Glacial till is a soft rock identified by large angular ...

The characteristics of the rocks that hold fossils can be as informative as the fossils themselves. There are three main types of rock: igneous rock, metamorphic rock, and sedimentary rock. Almost all ...

The principle of superposition states that in an undeformed sequence of sedimentary rocks, each layer of rock is older than the one above it and younger than the one below it (Figures 1 and 2).

"The fact that so many places are missing the sedimentary rocks from this time period has been one of the most puzzling features of the rock record," said C. Brenhin Keller, an assistant professor ...