Sedimentary rocks Flashcards
How do sedimentary rocks form?
How sedimentary rocks form – Sedimentary rocks are formed by sediments becoming cemented together through pressure and through natural substances in the sediments that act as cement
What are weathered sedimentary rocks?
- Weathered rock sediments – These rocks are formed by sediments that came of weathered pieces of rock. Sedimentary rocks that are formed from weathered rock sediments are known as clastic sedimentary rocks. Natural cements are chemicals that can flow around the sediments then set like cement. Natural cements include calcium carbonate, silica, quartz, iron oxide and clay minerals.
What are chemical sedimentary rocks?
Minerals crystallising from solution (Chemical sediments) – Chemical sedimentary rocks form when dissolved minerals turn into solid crystals and sink to the bottom of a lake, river, or sea. When it is at the bottom of the body of water, the crystals grow .This process is known as crystallization.
What are organic sedimentary rocks?
From dead animal or plant material (organic sedimentary rock) – Organic sedimentary rocks form when dead plant matter or animal debris accumulates and then is cemented together. The sediments are mostly from organisms but their may be small amounts of weathered rock.
What is the type of clastic sedimentary rocks?
Clastic – (Characteristics of clastic sedimentary rocks Have layers because the sediments build on on top of the other. The grains do not interlock because they did not grow crystals. The rock may contain fossils). Clastic sedimentary rocks are classified mainly according to the size and nature of the rock grains and chemical composition of the cement.
What is strata?
Sedimentary rock forms in layers called strata. A single layer is called stratum. Oldest sediments are at the bottom of strata and the newest are at the top.
