- Slides: 73
BIG Idea: • Surface water moves materials produced by weathering and shapes the surface of Earth.
• What types of bodies of water constitute surface water?
• rivers • lakes • streams • ponds • seas
• From where does surface water come?
• rain • ice • snow • under the ground
• Where does surface water go?
• under the ground • into the ocean • evaporates into the sky
I. THE WATER CYCLE (Hydrologic Cycle) • EVAPORATION: liquid water changes to water vapor (gas)
• TRANSPIRATION: plants give off water vapor into the air
• EVAPOTRANSPIRATION: combined processes of evaporation and transpiration
• CONDENSATION: change from water vapor to liquid water
• SUBLIMATION: ice slowly changes to gas without first entering a liquid state
• PRECIPITATION: water falls from clouds to Earth’s surface (in the form of rain, snow, sleet, hail)
• RUNOFF: water that flows over the land into streams and rivers
FACTORS THAT AFFECT RUNOFF: • soil composition • rate of precipitation • vegetation • slope
A. Water Budget • The water budget is like a financial budget… • You want both to be balanced.
• precipitation is the income • evapotranspiration and runoff are the expenses
II. RIVER SYSTEMS • Made up of a main stream and all the feeder streams that flow into it • Tributaries: feeder streams for rivers
• Watershed: area of land that drains into a lake, river or stream • Also known as the Drainage Basin
Chesapeake Watershed • 1 of the 3 major regional watersheds of VA • 15 million people live within the area • covers over 64, 000 square miles
Where do the 3 major regional watershed systems in VA lead? ØChesapeake Bay ØNorth Carolina Sounds ØGulf of Mexico
A. STREAM EROSION • CHANNEL: The path that a stream follows
STREAM LOAD: materials carried by a stream Fine sand silt; speed keeps particles suspended (not sinking to river bottom) Larger materials scrape along river sides and bottom along river bottom Short jumps made by bed load if the river is moving fast enough
Ways that sediments are carried in a stream: • Bed Load • Solution • Suspension
Bed Load • Large, heavy sediments are pushed or rolled along the bottom of a stream’s bed.
Saltation: Saltation Short jumps made by bed load if the river is moving fast enough.
Solution • Materials dissolved in a stream’s water.
Suspension • Particles small enough to be held up by the stream’s moving water.
• DISCHARGE: volume of moved water by a stream at a given time
• The faster the stream flows… • The higher its discharge… • The greater the load it can carry
• Gradient: steepness of the slope the stream is flowing down • The gradient is steepest near the headwaters (beginning of the stream)
B. STAGES OF A RIVER SYSTEM Youthful Mature and Old Rejuvenated
1. YOUTHFUL RIVERS • “V” shaped valley with steep sides • waterfalls and rapids • few tributaries • small volume of water
2. MATURE RIVERS • many tributaries • high volume of water • erosion occurs along widening valley walls and during floods
a. MEANDERS: series of wide curves
b. OXBOW LAKES: closed off meander isolated away from the main part of the river
3. OLD RIVER • low gradient with slow flow • no longer erodes land • starts to fill itself in with sediment
4. REJUVENATED RIVER • gradient of a river becomes steeper due to tectonic activity
Is this river young, old, or middle aged?
III. STREAM DEPOSITION • Deposition: the process by which Earth materials carried by wind, water, or ice settle out and are deposited (like money in the bank)
• How sediments are deposited
A. Delta: fan shaped deposit at the mouth of a stream
B. Alluvial Fan: delta on land due to the rapid reduction of a stream.
C. Flood Deposits 1. Flood Plain: part of the valley that may be covered with water during a flood.
2. Natural Levees: raised riverbank that results when a river floods.
IV. Glaciers Ølarge, moving masses ice Øform: of – near Earth’s poles and – in mountainous areas at high elevations Øcover about 10% Earth’s surface of
Two Types: 1. Valley Glacier: Øformed in mountainous areas Ølong narrow wedge of moving ice
Erode a U-shaped valley
2. Continental Glacier: cover millions of square miles (only found on Greenland Antarctica)
Glacial Till: unsorted rock, gravel, sand, and clay that glaciers carry and deposit • Moraine: unsorted ridges of till left behind when the glacier melts
Glacial Striations in Central Park, NY
Glacial Erratic in Central Park, NY (Pegmatite)