Rocks
By:Robert Ammitzboll
Rocks and How They Form
There are three different kinds of rocks: Igneous, Sedimentary,and Metamorphic. Each Rock is formed differently. Igneous rocks form from melting and resolidifying. Sedimentary rocks and formed when sediments and cemented and compacted together. Metamorphic rocks are formed when either igneous or sedimentary rocks are put under heat and extreme pressure.
Igneous Rocks
Igneous Rocks are formed by melting and re-solidifying slowly or quickly depending on where they re-solidify. There are intrusive which from inside the Earths Crust and the crystals have time to form and become coarse. Extrusive rocks form outside the Earths crust, and form quickly so there is not time for the crystals to become coarse, so therefore, they are fine.
Sedimentary Rocks
Sedimentary rocks are formed by cementation and compaction of sediments. These rocks are formed on the surface. These are the only rocks that have fossils in them. They are formed from cementation and compaction of sediments or shells.
Metamorphic Rocks
Metamorphic rocks are formed by heat and extreme pressure. The rocks are not melted because then they would become and igneous rock. They form deep within the Earth.
Gabbro
Gabbro is an igneous rock. Gabbro has very coarse Crystals. These crystals are formed because gabbro forms deep within the Earth. Since it forms deep within the Earth it takes a long time to solidify, so the crystals have time to from.
Limestone
Limestone is a sedimentary rock. Sedimentary rocks form from cementation and compaction of sediments. Limestone is a Chemically/organically formed rock. That means that salt water evaporates and leaves behind the salt and then it precipitates without the salt in it. but it is also organic or bioclastic which means that it has plant remains compacted and cemented into the rock.
Slate
Slate is a metamorphic rock. Which forms when an igneous or sedimentary rock is deep within the Earths crust and gets heated up but not melted, and put under extreme pressure. Slate is foliated which means there are bands of the rock or its almost layered.
The Rock Cycle
The Rock Cycle is just the cycle rocks go through to become other or the same rocks. Any rock can become any rock over again. It can melt and become an igneous rock, or it can be subdued to heat and pressure, or it can be weathered and eroded, then cemented and compacted into a sedimentary rock