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 ...

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There are three main types of rock: igneous rock, metamorphic rock, and sedimentary rock. Almost all fossils are preserved in sedimentary rock. Organisms that live in topographically low places (such ...

Rocks also differ based on how they were formed. Igneous rocks form out of cooling lava or magma. Sedimentary rocks develop from eroded grains of other rocks and organic matter. Metamorphic rocks ...

They accidentally discovered a band of sedimentary rock that contained unusually high levels of a rare element, iridium. Chemical dating techniques put the rock at around 65 million years old.