How do fossils get into the rock?

Most of the Earth's surface is covered with a type of rock called sedimentary because they form from layers of sediment on top of each other. One of the characteristic features of sedimentary rocks is the high amount of fossils they contain. All species of extinct plants and animals are preserved in sand, mud or mud from the age of the long past. Bones are subject to mineralization, with minerals replace the original organic substances to leave the occupation of the organism. After a long time, the body will become completely replaced by resistant minerals. In fossilization of wood, cellulose and wood fibers are replaced by minerals such as silica. In fossils were found eyes of flies and fine wings of butterflies. However, most fossils are strong shells or skeletons. Animals with permanent fossilijsa also some of the most commonly studied and understood.

It is surprising that something as soft and gentle as sand can turn into something sorigid as fossil. The reason is in the pressure that sediments are subject to when they are buried further and further. For every 100 feet (31 meters) depth, the average temperature increases by about 1 ° C. The average pressure increases about 1 ppsi (pound per square inch), or about 7 kilopascal, for each leg (31 centimeters) depth. Increased pressure and temperature leads to a process called compaction, with fine particles in the sediment are closely processed and becoming a rock.

mud is cleaned from water during the compaction process and becomes a rock. Sometimes increased heat leads to a material to submit chemical transformations called cementation, which causes minerals such as calcite, silica oxide and oxide with marketing films on the surface of the sediment. This is how fossils are formed. Minerals also occupy air pockets between sand molecules.

fossils can also maintain things other than real bodies. Traces, tracks, trails and burrows were found. Since coal is compacted by the vegetation itself, in itMany fossils can be found.