The exterior of the Empire State Building in NYC is made of limestone, marble, granite, and metal. Sedimentary & Metamorphic Rocks

SEDIMENTARY ROCKS Rocks are formed by the compaction and cementing layers of sediments. Sediments are materials such as rock fragments, plant and animal remains, and minerals that settle to the lake or ocean floor.

Formation Sediments – small pieces of rock that are moved and deposited by water, wind, glaciers and gravity. When sediments become “glued” together, they form sedimentary rock. Sediments produced by weathering and erosion form sedimentary rocks through the process of lithification.

Weathering produces rock and mineral fragments. Erosion removes and transports sediment.

Lithification describes the physical and chemical processes that transform sediments into sedimentary rocks. Lithify means to turn to stone.

Compaction and Cementation Lithification begins with compaction—the weight of overlying sediments forces the sediment grains closer together. Cementation occurs when mineral growth glues the sediment grains together into solid rock.

Sedimentary Layers Bedding – the way sediment settles out of water and wind – Graded bedding: bedding in which the particle sizes become heavy and coarse toward the bottom – Cross bedding: formed as inclined layers of sediment deposited across a horizontal surface

Graded bedding

Cross-bedding

Classification Sedimentary rocks are classified by their mode of formation. – Clastic rocks – Chemical rocks – Biochemical rocks

Clastic Rocks Formed from the abundant deposits of loose sediments that accumulate on Earth’s surface. Clastic means broken. Three types: – Coarse, medium, fine-grained

Coarse-grained rocks

Fine-grained rocks

Chemical Rocks The water in seas, lakes, swamps and underground reservoirs often contains dissolved minerals along the floor. These sediments form when these minerals precipitate or fall out of solution.

Rock Salt Flats

Biochemical Rocks Forms from sediments consisting of the remains of plants and animals. This quarry was once covered by water. Shelled organisms left behind fossils in the limestone sediment.

Coquina Fossiliferous limestone Mudstone

Sedimentary Features Stratification – a change in the type of sediment being laid down resulting in the formation of a new layer Fossils – the remains or impression of any plant or animal preserved in rock. Geodes – limestone that contains spheres of silica rock made entirely of quartz crystals.

METAMORPHIC ROCKS Rocks are formed by the effect of heat and pressure on other rocks. These rocks are exposed to the movements of Earth causing changes that give them new characteristics.

Textures Foliated – minerals are squeezed under high pressure and arranged in wavy layers or bands Nonfoliated – composed mainly of minerals that form blocky crystal shapes

Types of Metamorphism Regional metamorphism – high temperature and pressure affect large regions of Earth’s crust Contact metamorphism – when molten material comes in contact with solid rock

The ROCK Cycle Repeated series of events by which rock gradually and continually changes from one type to another