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

http://www.speedace.info/bonneville_salt_flats.htm

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.

CoquinaFossiliferous limestoneMudstone

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