Rocks are formed in three primary ways, and each method produces rocks with different characteristics. Rocks are either classified as sedimentary, igneous or metamorphic, depending on the manner in which they were formed. Most rocks encountered in everyday life are sedimentary, although some igneous rocks, such as granite, are also common.Know More
Sedimentary rocks are formed over thousands or millions of years as fine particles are compressed to form stones. As the layers accumulate, they impart incredible pressure on the bottom layers. Sandstone, limestone, shale and gypsum are all examples of sedimentary rocks. Sedimentary rocks often form in deltas and rivers because the constant flow of the river drags sediments from the river bed and deposits them in a confined area.
Igneous rocks are formed when molten rocks cool. Magma and lava spewing from volcanoes are the two most common source for igneous rocks. Granite, pumice, obsidian and scoria are all examples of igneous rocks.
Metamorphic rocks begin as either sedimentary or igneous rocks. Sometimes such rocks end up being moved into the deep parts of the Earth’s crust, where temperatures are high and pressures are extreme. These unusual conditions serve to heat and change the rocks. Marble, slate and gneiss are examples of metamorphic rocks.Learn more about Geology
Archipelagos form when underwater volcanoes continually produce molten magma that cools and builds up to eventually form a group of islands. Although archipelagos can form by erosion or by the movement or evaporation of water, volcanic activity is the most common cause of archipelago formation.Full Answer >
Rocks are different from minerals in that minerals are single crystalline accumulations of one or more elements, while rocks are solid accumulations of one or more minerals. Rock can either refer to a particular, detached object or, in a general sense, as a synonym for stone, generally referring to a portion of the substance. Individual minerals can be obvious in rocks, as with granite, or microscopic, as with many basalts.Full Answer >
Metamorphic rocks are formed when the properties of existing igneous or sedimentary rocks are altered by contact with heat or pressure. They are typically found deep underground where the conditions necessary for their formation exist.Full Answer >
Foliated rocks are a type of metamorphic rock formed under intense pressure that is greater in one direction. This pressure squeezes the flat or long minerals within the rock, causing the minerals to fold or align perpendicularly to the direction of the greatest pressure.Full Answer >