Chapter 10: Deposition Workbook p. 202-216

Deposition Opposite of Erosion Begins with weathering and erosion of materials To place sediments in a new place Released, settled, or dropped Releasing of solid sediments and the process of PRECIPITATION Releasing of dissolved minerals or salts from a water solution Forms sedimentary rocks

Depositional Features Beaches, flood plains, deltas, moraines, marine coastal plains, glacial deposits

Factors Causing Deposition If you remember, erosion occurs when the speed of the water in a stream, wind in a breeze, or other erosional surface speeds up Deposition occurs when these agents slow down or stop Think of a feather blowing in the wind When the wind stops, the feather ?

Rate of Deposition Time it takes for sediments to deposit Faster rate of deposition Less time it take Slower rate of deposition More time it takes TWO factors that affect rate of deposition Velocity of the erosional system Sediments themselves

1- Velocity of an Erosional System ESRT p. 6 Faster a stream flows, the larger sized sediments it can carry So, if the stream slows down below a certain velocity, it will deposit the sediments it can no longer carry

2- Characteristics of the Sediments Themselves The actual sediments will determine how fast they will be deposited in air or water environments: Size Larger sediments will settle out first If all other things are equal, the larger one will be heavier

2- Characteristics of the Sediments Themselves The actual sediments will determine how fast they will be deposited in air or water environments: Shape The more rounded the particle, the faster it will settle Flattened particles have more resistance pushing up on it, settle slower

2- Characteristics of the Sediments Themselves The actual sediments will determine how fast they will be deposited in air or water environments: Density More dense will settle faster. If all other factors are equal, the more dense will be heavier

2- Characteristics of the Sediments Themselves The actual sediments will determine how fast they will be deposited in air or water environments: Saturation of Dissolved Minerals More saturated materials are more likely to settle out faster

Open your workbook to p. 204 (1-4) 3 River slows down. Less kinetic energy 4

Sorting of Sediments Sorted Sediments Deposit or layer of sediments that has particles of the same size (or shape or density) together. Most common type of sorting performed Usually found in water and wind deposits The greater the similarity , the more sorted the sediments are There is vertical sorting and horizontal sorting

Graded Bedding When sorting occurs again and again

Unsorted Sediments Mixture of sediments all together Most common in glacial deposits and mass movements

Dynamic Equilibrium A type of equilibrium that is constantly changing The rate of erosion is equal to the rate of deposition by the system as a whole If a stream floods, more erosion will occur. Eventually, those particles will deposit somewhere and a new equilibrium will occur.

Open your book to p. 206 (5-14) 3 4 Unsorted 1 2

Characteristic Features of the Chief Depositional Agents Each agent has its own characteristic features 5 Agents of Depositioning: Streams Glaciers Waves and Currents Wind Mass Movement

1- Streams Deposited on the inside of meanders, where the velocity is slower Flood plain- flat region to the sides of a stream where the stream floods Oxbow Lake- former meander Curved Lake Delta- Where a fast moving stream enters a slower moving body of water (lake or ocean) Horizontal deposition of sediments Shape of a TRIANGLE Horizontal and vertical sorting is commonplace

2- Glaciers Sediments deposited by a glacier is called glacial till Glacial till is angular, poorly sorted, and unlayered Moraine- the place where a glacier stops moving forward Sediments are dropped in completely UNSORTED piles Ground moraines, Terminal moraines Central Long Island is a terminal moraine from the last ice age Drumlins Shaped like the back of a spoon Points in the direction of the glacial movement UNSORTED sediment Kettles and Kettle Lakes Blocks of ice that were left behind and melted If it fills with water, it is a kettle lake Erratic Piece of rock moved there by a glacier and dropped Doesn’t look like it “belongs” Outwash Plain Similar to a flood plain, but where a piece of a glacier has flooded an area with melted ice Forms a delta-like feature

3- Waves and Currents The bottom of waves slow down as the approach the shore Moves sediment toward the shore Also, what causes waves to “break” Beach- strip of sediment at the coastline Made up of sediment of broken down rocks, etc found just offshore Why parts of Hawaii has black sand- cooled lava Why Bermuda has pink sand- red coral and white sand Why Staten Island has brown sand- clay based Peninsula or pier- sand will deposit on the side that the waves are going TOWARD it. The side opposite the waves will have erosion Sandbar- created by a longshore current Current that runs parallel to the beach Shallow spot offshore Barrier Island When a sandbar reaches the surface of the water Water is still between the barrier island and mainland

Wave and Current Features

4- Wind Usually only transports sand and smaller sized particles Silt and clay is called dust Sand dunes- “hills” of sand Sloping, sorted sediment Gentle slope facing the wind and a steep slope on the leeward side

5- Mass Movement Completely unsorted and unlayered sediments Sharp, angular sides Pile of sediments at the bottom of a cliff

Open to p. 210 (15-25) 2 3 1 4