TRANSVERSE CONTRACTION JOINTS. The primary purpose of transverse contraction joints is to control the cracking that results from the tensile and bending stresses in concrete slabs caused by the cement hydration process, traffic loadings, and the environment.
Diamonds are found in igneous rock which is brought to the surface of the earth by volcanic eruptions bringing magma to the surface. Diamond itself is strictly an allotrope of the element carbon, a mineral, one form of crystal that can be created from carbon.
1 Magma is molten rock that flows beneath the earth's surface. 2  Igneous rocks are formed by cooling magma. 3  The location of the formation of the rock, as well as how fast the magma cools will determine the type of igneous rock. 4  Intrusive rocks form from the cooling of magma deep beneath the earths surface. Igneous rocks that form too quickly for crystals to form have what is called a glassy texture. 2  Obsidian is the only glassy igneous rock, and can be identified by its dark color. 3  This looks like dark black glass.