How do fossils get into rocks?

Most fossils are thick shells or skeletons.

Most of the Earth’s surface is covered by a type of rock called sedimentary, because it forms from layers of sediment that accumulate. One of the characteristics of sedimentary rocks is the large amount of fossils they contain. All kinds of extinct plants and animals are preserved in the sand, silt or mud of ancient times.

When wood petrifies, cellulose is replaced by minerals.

Over time, animal carcasses on sedimentary rock surfaces are covered by silt. Bones undergo mineralization, whereby minerals replace the original organics to leave a mold of the organism. Over time, the body is entirely replaced by durable minerals. In the petrification of wood, cellulosic and woody fibers are replaced by minerals such as silica.

Earth’s sedimentary rocks contain a relatively large amount of fossils that formed from plants, animals and marine life preserved long ago in sand, silt or mud.

Even delicate features are sometimes preserved in fossils. The eyes of flies and the delicate wings of butterflies have been found preserved in fossils. Most fossils, however, are thick shells or skeletons. Animals with enduring fossils are also some of the most widely studied and understood.

It is surprising that something as soft and subtle as sand can turn into something as rigid as a fossil. The reason lies in the pressurization that sediments undergo as they are buried deeper and deeper. For every 100 feet (31 meters) of depth, the average temperature increases by about 1 °C. The average pressure increases by about 1 ppsi (pound per square inch), or about 7 kilopascals, for every foot (31 centimeters) of depth. depth. The increase in pressure and temperature leads to a process called compaction, in which the delicate particles of sediment stick together and form rock.

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Sedimentary rocks often contain large numbers of fossils due to the way their layers accumulate over time.

Sludge is purified from water during the compaction process, becoming rock. Sometimes the increased heat causes the material to undergo chemical transformations, called cementation, which cause minerals such as calcite, silica and iron oxide to build up films on the surface of the sediment. This is how fossils are made. Minerals also occupy air pockets between sand molecules.

Fossils can also preserve things other than actual bodies. Footprints, footprints, trails and burrows were found. Since coal itself is compacted vegetation, many fossils can be found within it.

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