IGNEOUS
ROCKS
form as the result of cooling molten material, such as lava from a volcano.
Fossils are very rare in igneous rocks. (eg. basalt, granite)
SEDIMENTARY
ROCKS
consist of sand, mud and other materials that settled under water or on land.
As they did so they built up deposits called strata. Fossils are common in
sedimentary rocks and some such as coal consist entirely of fossil material.
(eg. shale, sandstone, limestone)
METAMORPHIC
ROCKS
formed either from igneous or sedimentary rocks by alterations from the rock
due to high temperatures and pressures. Fossils in metamorphic rocks are relatively
rare and are commonly quite poorly preserved. (quartzite, marble)