Download Water Erosion: _ How do processes involving water change Earth`s

Water Erosion: _
How do processes involving water change Earth’s surface?
What is the ​
MAJOR​
agent of erosion that has shaped Earth’s land surface? Water Erosion
Water moving over land’s surface is called runoff. This may cause sheet erosion.
The amount of water runoff in an area depends on 5 main factors:
1.
2.
3.
4.
5.
The amount of rain an area receives.
Vegetation - grasses, shrubs & trees reduce runoff
Type of soil - some absorb more water than others
Shape of the land – steep slopes has more run-off, which causes more runoff
How people use the land - paved areas increase run-off, crop removal increases run-off
Runoff overtime:
How does runoff over time affect the land and water?
Rivers cause erosion and create valleys, waterfalls, flood plains, meanders and oxbow lakes.
Rivers form on steep mountain slopes. They flow quickly & follow a narrow path so they erode rapidly. The result is
that rivers form deep, V-shaped valleys.
Features of rivers:
What are the features that erosion forms along a river?
Deposits by rivers are made as the water slows down and the fine particles settle in the river bed. Larger stones quit
rolling and sliding. Deposition creates landforms such as alluvial fans and deltas and can also add soil to a river’s flood
plain.
Deposits by Rivers:
What features result from deposition along a river?
Groundwater Erosion:
What results from water seeping into the ground & mixing with CO​
2?
Not all rain water evaporates or becomes runoff. Some water soaks into the ground, filling openings in the soil and
trickling into cracks & spaces in layers of rock. Groundwater erosion is caused by the process of chemical weathering:
Carbonic Acid forms as carbon dioxide & water combine. This weak acid can break down limestone that will gradually
hollow out pockets in the rock. Over time, the pockets develop into large holes called caves or caverns.
Cave Formations:
What are the features found in a cave? How do they form?
Water containing carbonic acid & calcium drip from a cave’s roof forming ​
stalactites ​
(like​
icicles hanging from
​
the top) and ​
stalagmites​
(drips the build up from the bottom of the cave floor)
Karst Topography​
: What happens when land rich in limestone is weathered by groundwater?
In rainy regions where limestone near the surface is weathered and groundwater erosion can cause the roof
of the cave to collapse leaving a sinkhole – this type of landscape is called karst topography. In the U.S.
regions of Florida & Texas have these areas.
Erosion by Glaciers: _ How do glaciers cause erosion and deposition?
Glaciers:
A​
glacier​
is any large mass of ice that moves slowly over land and form in areas where ​
more snow
falls than melts.​
(Watch Brain Pop – Free Movie - Glaciers)
What are the 2 types of glaciers? How are they alike? How are they different?
How do Glaciers shape the land?
They begin to move due to the force of gravity and erode the land by plucking & abrasion
Plucking ​
happens as glaciers​
move across the land. They pick up rocks, the weight of the glacier breaks
them apart & they freeze to the bottom of the glacier and the glacier carries the rock fragments along with it.
As the glacier drags the rocks along, the land is gouged & scratched by the rocks. This process is called
Abrasion.
Glaciers make deposits along the land as they melt and drop the sediments on their bottoms as ​
till​
– particles
of different sizes – clay, silt, sand, gravel & boulders can be found in till. Till deposited along the edges of a
glacier forms a ridge called a m
​oraine​
. Long Island in New York is a terminal moraine (it was the very last
point reached by the glacier that deposited it). As glaciers melt they leave their marks called k
​ettles​
– small
depressions left in areas when chunks of ice are left in glacial till. They fill in with water and form ponds or
lakes - called kettle lakes (common in Minnesota)
Erosion by Waves: _ How do waves erode a coast? What features result
from deposition by waves?
Remember: Waves are caused by the energy from the wind being transferred to the water.
Erosion by Waves:​
Waves shape the coast through erosion by breaking down rock and transporting sand
and other sediment. They erode hard, rocky areas of the coast that jut out just like jagged mountains are
eroded over time.
Deposits by Waves:​
Waves deposit sediment as they slow down. Beaches, spits & barrier beaches are
formed.
Erosion by Wind: How does wind cause erosion? What features result from
deposition by wind?
Wind causes ​
erosion​
by deflation & abrasion
Wind is the weakest agent of erosion, but can be powerful in shaping the land in areas where there are few
plants to hold the soil in place. Example: the deserts
Deposition​
by wind forms sand dunes (plant roots hold in place) and loess deposits (makes fertile soils,
valuable farmland)