-Form when rock fragments, organic materials or minerals that precipitate out of solution are compacted or cemented together.
3 types of sedimentary rocks-clastic, organic and chemically formed.
-Are largely composed of solid sediments (pieces of rock) such as sand in sandstone.
Steps needed to form produce a clastic sedimentary rock
1. Weathering and erosion of preexisting rocks
2. Deposition of rocks fragments called sediments
3. burial beneath other sediments
4. weight of overlying sediment compacts or cements fragments together=rock
Weathering=breaking down rocks by chemical or physical processes into fragments or sediments
Erosion=carrying away of sediments by either wind, water, ice or gravity
Cementation=water gets between fragments and dissolved minerals are left behind as water is squeezed out or evaporates. The minerals act as glue keeping sediments together.
Are made up of intergrown or interconnected mineral crystals of just one mineral.
All natural water on earth contains dissolved minerals
Chemical processes form the rock-the entire rock is formed from 1 mineral left behind from water as it
A) Evaporates
B) Is saturated with minerals-
Dissolved minerals fall out of solution or precipitate
-Remains of organisms are compacted together to get rocks
Limestone-dead sea organism's shells cement together
Coal-dying plants and trees compacted after decay in swamps
1. Bedding-appearance of layers of rock fragments-
Clastic
2. Interlocking same type crystals-chemically formed
3. Fossils-organic and clastic
4. Range of particle size-various sized particles in same
rock(conglomerate) or rock made of just one size
particle(shale)
5. Rounded or angular fragments-clastic
Fossils can only be found in sedimentary rocks. They can not withstand the heat and pressure of metamorphism, nor can they withstand melting to form an igneous rock.