Earth ScienceCoach Williams

Room 310B

Formation of Sedimentary Rocks

Chapter 6.1

Formed by cemented sediments

Sedimentary Rocks

Solid material Deposited on Earth’s surface Wind, water, ice, gravity, chemical

precipitation Form sedimentary rocks

Sediment

Sediment

Earth’s crust is worn down Physical or chemical processes Clastic sediments- rock or mineral

fragments◦ Greek klastos = broken

Weathering

Removal and movement of rock fragments 4 Main ways:

◦ Wind◦ Moving water◦ Gravity◦ Glaciers

Deposition- sediments laid down◦ Land and water

http://www.youtube.com/watch?v=51C7vEAVbxk

Erosion

Erosion

Sediments become rock Greek lithos = rock Layers of sediment = pressure Deep layers = hot temperature Cementation- mineral growth cements

sediment together

Lithification

Bedding- horizontal layering Graded Bedding- larger/heavier fragments

at bottom layers Cross-Bedding- layer crossing over another

one

Features of Sedimentary Rock

Cross Bedding

Preserved evidence of once-living organisms◦ Remains or impressions

Found in sedimentary rocks

Fossils

Types of Sedimentary Rocks

Chapter 6.2

Clastic- deposited loose fragments Chemical- dissolved minerals left behind

Types of Sedimentary Rocks

Classified by sediment size Coarse-grained: gravel-sized fragments Medium-grained: sand-sized fragments Fine-grained: silt-sized fragments

Porosity- % of open spaces

Clastic Sedimentary Rocks

Clastic Sedimentary Rock

Evaporation- leaves minerals behind◦ Evaporites: rocks formed this way

Organic- remains of once-living organisms◦ Shells, bones◦ Coal- remains of plant material; carbon; fuel

Chemical Sedimentary Rocks

Energy- coal, natural gas, oil, nuclear Fertilizers Iron Walls/buildings Snapshot- cross bedding & fossils

Importance of Sedimentary Rocks

http://geology.com/rocks/sedimentary-rocks.shtml

Pictures of Sedimentary Rock

Metamorphic Rocks

Chapter 6.3

Temperature/pressure changes rocks◦ Composition, minerals, texture

Meta = change Morph = form

Metamorphic Rocks

Regional: large regions Contact: molten rock touches solid rock Hydrothermal: hot water alters rock

Types of Metamorphism

Foliated: minerals are wavy layers/bands Non-foliated: no mineral grains in one

directions

Metamorphic Textures

http://geology.com/rocks/metamorphic-rocks.shtml

Pictures of Metamorphic Rock

Changing and re-making of rocks

Rock Cycle

Rock Cycle