Earth Science
Major Rock Types​
Igneous Rocks
Igneous rocks are rocks formed went molten lava cools and crystalizes. The speed of crystallization will affect the rock's texture and affects the size of the crystal structure, the more time a crystal has to cool the larger it will become. These rocks also come in two forms: intrusive and extrusive which refer to rock formations that cooled below the ground and were driven upward over time and lava that cooled on the surface respectively. Finally they come in two subtypes, mafic and felsic, mafic rocks are darker in appearance and full of magnesium and ferric oxides leading to them taking on more black or grey tones while felsic are more white or pink in color and are high in feldspar.
Metamorphic Rock
Metamorphic rocks are formed by igneous, sedimentary and other metamorphic rocks which are exposed to extremely high pressure or heat. These rocks are often found at plate boundaries/in mountain ranges or where mountains once existed which can easily provide the pressure needed to form these rocks as can be seen in New York as much of the metamorphic bedrock in the area is blue schist (an extremely high-pressure metamorphic rock).
Sedimentary Rocks
Sedimentary Rocks are formed from weathered deposits of rock produced by ice, wind, gravity, water flows, etc and the material of dead organisms that accumulate on the earth's surface (ocean floor also counts) over time this rock is compacted and cemented forming sedimentary rock formations. These formations are often found at ancient seas or the base of mountains where sediments like to build up.
