The Rock Cycle The rock cycle begins from volcanic deposition of igneous material on the surface, some of this material is subjected to weathering, and produces fine particles that comprise sediment. Through Litification , (layers upon layers create huge pressures), this material forms Sedimentary Rocks. When this material is buried at a depth of around 40,000 feet, Diastrophasism takes place and the combination of heat (from the increased temperature at this depth) and pressure forms Metamorphic Rocks. Igneous rocks are produced from within the earth, where the outer core is liquid molten material, and some of this finds it's way to the surface, taking various other material along the way with it as it melts and includes the mantle, oceanic crush and continental crust on its way through cracks and fissures towards the surface, where it is deposited as either magma, or in fractures of the crust. This is how the three types of rocks are produced, Igneous, Sedimentary and Metamorphic. Igneous Rocks Generally speaking, igneous rocks are of two types, extrusive (volcanic) rocks that form from magma flowing onto the surface and intrusive (plutonic) rocks, that form as the magma cools below the surface. A batholith is the largest body of intrusive igneous rock, which is a formation at least 100 square kilometers in area. Other types of igneous formations include: Lacolith - which is a concordant igneous intrusion that arched up into the strata, and it forms a lens shaped body, with a genrally horizontal floor. Discordant - which is a flow that cuts across the plane of rock layers. Concordant - which is a flow that runs parallel to rock layers. Lava - the term that applies to Magma once it reaches the surface. Fissure Erruptions - which is the term applied when magma flows to the surface through fissure cracks in the crust.

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