Minerals

The substances that make up rocks and Earth’s surface

Sedimentary Process

• Physical & Chemical process of weathering and erosion • Breaking of rocks into smaller pieces

sediment• Sediment = loose particulate material

(clay, sand, gravel, etc.)

What are the main agents of weathering & erosion?

•Wind•Moving water • Gravity • Glaciers

Text p 135 figure 6.2

Sediment

• Deposited in low areas• Largest grains sink to the bottom and

the smallest grains at the top resulting in layers• As more sediment is deposited the

bottom layers are subject to increasing pressure & temperature causing Lithification

strata (layers)

Sedimentary Rock

Lithification

• Lithify Greek word lithos which means stone • Physical & Chemical process that transforms

sediments into sedimentary rocks–Compaction–Cementation

Sediments harden into rock

Sedimentary Rock

• Most formed under water but also in deserts/dunes • Cemented

together by SiO2, CaCO3 or FeO

Classification of Sedimentary Rocks

How rock was formed• Clastic: From pieces of other rocks • Chemical: Precipitating out of a

solution• Biochemical: From remains of plants &

animals

Clastic • Greek work klastos meaning broken • Most common sedimentary rock • Sandstone, shale • Further classified by size of particles –Coarse grain–Medium grained –Fine Grain Text p 142 Table 6.1

Chemical & Biochemical

Chemical • Forms in arid regions mostly called evaporites

(example Great Salt Lake in Utah) • Limestone, rock salt

Biochemical • Organic, common in shallow waters • Coal, limestone

Common types of sedimentary rocks

ShalesMudstonesSandstones Limestones

Evaporites (such as salt beds)

Shales are the most common sedimentary rock type being made up of fine particles

Sandstones are made up of sand-sized grains most common is quartz

Limestone is a light whitish-gray

Identifying Sedimentary Rock

Some show ripple marks or mud cracks

Desert Salt Flat

Ancient shallow water environment

Why do you think most fossils are found in sedimentary rock?

Homework

Read text p 134-137 & 141-144

ANY QUESTIONS?