Formation of Sedimentary Rocks

1. What is sediment? Sediments are pieces of solid material that have been deposited on Earth’s surface by wind, water, ice, gravity, or chemical precipitation. When sediments become cemented together, they form sedimentary rocks.

2. Weathering Step 1 Earth’s surface is subject to weathering, a set of physical and chemical processes that break rocks. During physical weathering, rocks break into smaller pieces.

2. Weathering Chemical weathering occurs when minerals in a rock are dissolved or chemically change. During chemical weathering, less-stable minerals break down and stable minerals get smaller.

Step 2 3. Erosion and Transport After weathering, rock fragments are transported to different locations. The removal and movement of surface material from one place to another is called erosion. There are 4 main agents of erosion: wind, water, gravity and glaciers.

3. Erosion and Transport

3. Erosion and Transport

Bill Nye video

4. Deposition Step 3 Deposition occurs when sediments are laid down on the ground or sink to the bottom of water bodies. Particles settle in layers. Largest sediments will settle first, followed by smaller sediments. Why? Sometimes sediments do not form layers. Glaciers move all sediments equally.

Great Salt Lake in Utah contains many minerals dissolved in it.

4. Deposition

5. Burial Step 4 Most sediments eventually end up in the lowest places on Earth, called basins. Basins can be over 8 km thick. As more sediment is deposited, increasing pressure and temperature cause lithification. Lithification is the physical and chemical process that transforms sediments into sedimentary rock.

Tucson is in a basin.

Step 5 6. Lithification Lithify comes from the Greek word lithos, meaning stone. Lithification begins with compaction. The weight of over-lying sediments forces the grains closer together, causing physical changes.

6. Lithification Sediments buried deep enough (3-4 km) experience temperatures that are high enough for cementation to occur. Cementation occurs when mineral growth cements (glues) sediment grains together. Calcite and Iron oxide are common cements.

6. Lithification Draw this!

7. Features of Sedimentary Rocks: Bedding Bedding – horizontal layering of sediments. Graded bedding – When bedding becomes progressively heavier and coarser towards bottom layers. Cross-bedding – horizontal layers that are tilted and cross each other.

Bedding examples: horizontal

Bedding examples: horizontal Draw this!

Bedding examples: graded Draw this!

Bedding examples: cross-bedded Draw this!

7. Features of Sedimentary Rocks: Fossils Fossils – the preserved remains, impressions, or other evidence of once-living organisms. When an organism dies, it may be buried before it decomposes. If remains are undisturbed, it might become preserved as a fossil.

7. Features of Sedimentary Rocks: Fossils During lithification, all or parts of the organism can be replaced with minerals and turn into rock.

8. Classification of Sedimentary Rocks Clastic sedimentary rocks are composed of weathered bits of rocks and minerals. - Examples: Shale (most abundant), Sandstone, Conglomerate Chemical sedimentary rocks form when dissolved substances separate from water. - Examples include: limestone and coal

8. Common Sedimentary Rocks Sandstone

Conglomerate

Shale with Plant Fossils

Limestone

Fossiliferous Limestone = Coquina

Classification of Sedimentary Rocks Use texture and composition to identify

Sedimentary Rock Classification chart Texture (grain size) Parent Sediment Rock Name Coarse, rounded Coarse, angular Medium Fine Very fine Gravel Conglomerate Gravel Breccia Sand Sandstone Mud Siltstone Mud Shale

Chemical Sedimentary rock classification chart Composition Texture Rock Name Calcite Altered plant matter Fine to coarse crystalline Limestone Various sized shells and shell fragments, loosely cemented together Coquina Fine-grained organic matter Coal

Add these notes to your table of contents Add these notes to your table of contents! Introduction to Sedimentary Rocks

Sedimentary Rocks Mini-lab Look at the samples at lab and fill in the table using your Sedimentary Rock ID chart.

Fossils are found in only one type of rock…. Sedimentary!! http://glencoe.mcgraw-hill.com/sites/0078695104/student_view0/brain_pop_movies.html#

B. Metamorphic Rocks http://www.classzone.com/books/earth_science/terc/content/visualizations/es0607/es0607page01.cfm?chapter_no=visualization

Metamorphic Rocks Formation of Metamorphic Rocks  Metamorphism means “to change form.”  Most metamorphic changes occur at elevated temperatures and pressures.  Happening below Earth’s surface!!!

4.4 Metamorphic Rocks Main Agents of Metamorphism  Heat Provides the energy needed to drive chemical reactions  Pressure Causes compaction and greater density

Metamorphic Rocks Classification of Metamorphic Rocks  Two main categories 1. Foliated Metamorphic Rock Has a banded or layered appearance Example: Gneiss 2. Nonfoliated Metamorphic Rock No banding Examples: Quartzite, Marble

Foliated Metamorphic Rock Classification chart Grain size Comments Parent Rock Rock Name Very fine Smooth and dull shale Slate fine Breaks along platy surfaces, glossy sheen slate Phyllite Medium to coarse Shiny minerals dominate Schist Banding Schist or granite Gneiss

Non-Foliated Metamorphic Rock Classification chart Grain size Comments Parent Rock Rock Name fine Interlocking calcite grains Limestone Marble Medium to coarse Fused quartz grains Sandstone Quartzite

Gneiss Typically Displays a Banded Appearance

Marble—A Nonfoliated Metamorphic Rock