EVERYDAY SCIENCE

Detailed explanation-1: -There are three main types of rocks: sedimentary, igneous, and metamorphic. Each of these rocks are formed by physical changes-such as melting, cooling, eroding, compacting, or deforming-that are part of the rock cycle . Sedimentary rocks are formed from pieces of other existing rock or organic material.

Detailed explanation-2: -Igneous rocks are formed from melted rock deep inside the Earth. Sedimentary rocks are formed from layers of sand, silt, dead plants, and animal skeletons. Metamorphic rocks formed from other rocks that are changed by heat and pressure underground.

Detailed explanation-3: -Common sedimentary rocks include sandstone, limestone, and shale. These rocks often start as sediments carried in rivers and deposited in lakes and oceans. When buried, the sediments lose water and become cemented to form rock. Tuffaceous sandstones contain volcanic ash.

Detailed explanation-4: -Large amounts of granitic intrusions are also associated with regional metamorphic rocks. The most common regional metamorphic rocks are slates, schists and gneisses.

Detailed explanation-5: -All three types of rock make up the Earth’s lithosphere, the outermost layer. The lithosphere averages about 100 kilometers in thickness.