Aim: How can we explain deposition?

Deposition The dropping of transported materials (sediments), or the process by which transported materials are left in new locations. A.K.A. Sedimentation No deposition without erosion.

Erosion occurs when wind, water, etc Erosion occurs when wind, water, etc. is gaining speed, and deposition occurs when it is losing speed.

Factors affecting deposition Particle size: the larger the particle, the faster it settles Smallest particles remain suspended for days

Particle shape: the more spherical a particle the faster it settles.

Density: materials with a higher density settle faster.

Sorting: When mixed sediments are released into a column, the roundest, most dense materials will settle first.

Vertical Sorting Called ‘graded bedding’ The deeper the water the greater the sorting. Bed4 Bed 3 Bed 2 Bed 1

Horizontal sorting When a stream slows down, largest particles are left behind first. As velocity slows more, the next smallest size will deposit. Small particles carried the farthest

Deposition by Ice Glacial deposits are typically angular and unsorted.

Deposition by Ice Glacial Till- Material that is unsorted and deposited directly by glacial ice Terminal Moraine – Sediments deposited at the end of the glacier at the furthest retreat of a glacier. Drumlin – elongated hill composed of glacial deposit that show the direction of ice flow.

Glacial Till

Terminal Moraine

Drumlins

Wind Deposited Sediments Usually consist of well sorted, small particles in layers that may be tilted - this is called Cross Bedding.

Regents Questions Deltas form where (1) A ground moraine is deposited (2) Stream velocity is reduced (3) Small streams empty into larger streams (4) Extensive ground water action has occured

A mixture of sand, pebbles, clay, and silt, of uniform shape and density, is dropped from a boat into a calm lake. Which material most likely would reach the bottom of the lake first? Sand Pebbles Clay Silt

A glacier The wind Running water Wave action A low hill is composed of unsorted sediments that have mixed grain sizes. This hill was probably deposited by A glacier The wind Running water Wave action