2 Objective1. Define deposition as the process by which Earth materials carried by wind, water, or ice settle out and are deposited.2. Describe the agents of erosion: gravity, water (running water and waves), glaciers, and wind.3. Explain that running water (rivers, streams, and runoff) is the major cause of erosion.
3 Objective4. Identify the sources of fresh water on the Earth’s surface.5. Describe the process of stream development and the associated landforms.6. Design and construct experiments using stream tables to infer relationships between gradient, slope, speed, and extent of weathering and erosion.7. Explain the types of deposition specific to streams and rivers (such as alluvial fans and deltas).
4 Enduring Understanding Weathering, erosion, and deposition are interrelated processes that form a cycle of forces that wear down and build up the Earth’s surface.Water is continuously passed through the hydrologic cycle.Fresh water is necessary for survival and most human activities.
5 Stream DevelopmentAs a stream develops it changes shape, width, and size as well as the landscapes over which it flows.
6 Stream DevelopmentStreams are responsible for the majority of the landforms we see todayAlluvial Fan
7 Stream DevelopmentPrecipitation supplies the water for the beginnings of stream development
8 Stream DevelopmentHeadwaters is the region where water first accumulates to supply a stream
9 Stream DevelopmentHeadwaters are commonly found high in the mountains
10 Stream DevelopmentStream channel is a narrow pathway carved into the sediment or rock by moving water
11 Stream DevelopmentStream bank is the ground bordering each side of the stream
12 Stream DevelopmentStream piracy occurs when one stream draws away water from another
13 Stream ValleysAs a stream actively erodes its path through the sediment or rock it develops a specific recognizable landform
14 Stream ValleysV-Shaped channels are formed by streams and have steep sides that form at an angle
15 Stream ValleysGorges and canyons are very old V-shaped channels
16 Stream ValleysThe Grand Canyon formed by the Colorado River is one very recognizable V-shaped valley
17 Stream ValleysBase level is lowest elevation a stream will cut its valley to and coincides with the level of the lake or larger stream it runs into
18 Stream ValleysSea level is the ultimate base level
19 Meandering StreamsAs streams continue to cut and widen their channels the amount of water and sediment they can carry increases.
20 Meandering StreamsAs the stream approaches base level the slope decreases and water builds up it begins to erode the sides of the channel.
21 Meandering StreamsMeander is the bend or curve in a stream channel
22 Meandering StreamsThe water flowing in a stream moves at different speeds. It is fastest in the middle of a straight flowing stream because friction slows the sides and bottom.
23 Meandering StreamsWhen a stream begins to make a turn this changes and forms very interesting features
24 Meandering StreamsWater on the outside of the curve flows faster than the water on the inside of the curve
25 Meandering StreamsThis water erodes away the outside bank and makes the meander even larger
26 Meandering StreamsCut bank is the result of the greater erosion
27 Meandering StreamsThe slower water on the inside of the curve causes deposition of the sediment
28 Meandering StreamsPoint Bar is the resulting feature
29 Meandering StreamsOxbow Lakes are meanders that become completely blocked off by deposition of sediment
30 Stream DepositionAs streams slow they lose their ability to carry sediment. This is most commonly the result in a decrease in gradient or slope of the landscape over which the stream flows
31 Stream DepositionAlluvial fan is the sloping deposited sediment at the base of a steep slope and is most commonly found at the base of mountains in dry regions
32 Stream DepositionDelta is the triangular deposit that forms when a stream enters a large body of water.
33 Stream DepositionDeltas grow as stream deposition blocks the pathway of the moving water and smaller distributary streams branch out to form their own deposits
34 Stream DepositionThe Mississippi River delta began forming millions of years ago but it has deposited enough sediment in just the last 5,000 years to build the city of New Orleans on