What type of rocks do fossils form in

Since sandstone is a coarser material than shale or limestone, fossils found in them do not usually show as many details as fossils in shale and limestone. Sandstone rarely contains delicate fossils. Sandstone forms in a wide range of environments, including beaches, oceans, sand bars, dunes, rivers, deltas, deserts and flood plains. Sandstone contains fossils of creatures such as trilobites, brachiopods, crustaceans, bryozoans and plants.

Remains of land animals like mastodons and dinosaurs are much more likely to be found in sandstone. Conglomerate rocks form from combinations of large and small rounded pebbles, often containing quartz, cemented together over time. Breccia forms from angular rocks of various sizes, also cemented over time. They form faster than shale, limestone and sandstone.

Conglomerates form where rocks have been broken and then tumbled until smooth. Breccias form when the broken fragments remain close to their source. In both cases, their large particles are not as likely to incorporate fossils. Conglomerate and breccia rocks do provide fossils periodically, however, in the pebbles that make up the rocks. Some fossils found in conglomerate and breccia rocks include sponges, brachiopods and gastropods.

Fossils rarely occur in metamorphic or igneous rocks. The heat and pressure required to change, or metamorphose, rocks usually destroys any fossils. However, special circumstances do happen. For example, fossilized shells and bacteria have been found in marble, which is metamorphosed limestone. The initial heat of igneous rocks would seem an impossible environment for fossil formation.

Fossils typically don't form in metamorphic rock due to the high levels of pressure and temperature required to form them - any fossils that may be present are generally destroyed. Igenous rocks almost never form fossils as they're formed from molten magma, which also destroys the fossil. In what type of rock do fossils usually form in? Earth Science. Thomas U. Nov 6, Sedimentary rock. It's unclear how the organic material is preserved, but iron might help the proteins become cross-linked and unrecognizable, or unavailable to the bacteria that would otherwise consume them, Lacovara said.

Formaldehyde works in a similar way, cross-linking the amino acids that make up proteins, making them more resistant to decay, Mary Schweitzer, a molecular paleontologist at North Carolina State University, told Live Science.

Another idea is "microbial masonry," Lacovara said. Moreover, sandstone — rock made of sand-size grains of minerals, sediments or inorganic material — seems to be the best type of environment for preserving organic material in fossils.

Maybe we need the bacteria to get through fast and to chomp through the sediment so that they can sequester some of [the surviving organic material] in the process. Follow Laura on Twitter LauraGeggel. Original article on Live Science. Live Science. Joseph Castro.