Geography Chapter 2.4 external forces

2. Wind, heat, cold, glaciers, rivers, and
floods alter the surface of the earth.
The results of weathering and erosion
change the way humans interact with the
environment.

3. Weathering is the physical and chemical
processes that change the characteristics of
rock on or near the earth’s surface
Can change landscapes over time and create
soil for plant life
- Occurs slowly over MANY years, even centuries

4. The image shows
weathering of
sandstone and shale.
The steep cliffs are
made up of
weathering resistant
sandstone, while the
slope at the base of
the cliff is composed
of rock units
containing a larger
abundance of shale.

5. The surface
pattern on this
pedestal rock is
honeycomb
weathering,
caused by salt
crystallization.
This example is at
Yehliu, Taiwan.

6. • A maze of hoodoos in Bryce Canyon National
Park in southern Utah in the early morning. This
photo was taken on a sunny day in May 2002.

7. Weathering creates smaller and smaller
pieces of rock called sediment.
-Sediment can be identified as fine particles of rock
such as mud, sand, silt, etc.

9. Processes that break
rock into smaller
pieces
- Does not change the
composition of the rock –
ONLY ITS SIZE!
- Many factors can
contribute to mechanical
weathering including;
water, ice, wind, plants,
animals and even humans!

13. Occurs when rock is actually changed into a
new substance due to the interactions of the
elements in the air, water or minerals.
- Climates that are warm and moist will produce more
chemical weathering than cool dry areas.

17. Sea caves form from
carbonation, a type of
chemical weathering.

18. Occurs when weathered material is moved by
the action of wind, water, ice, or gravity.
Ex. Water carrying topsoil from a hill into a river will
cause the river to narrow.

20. 1) when water flows in a stream or river,
picks up loose material and moves it
downstream

21. 2) abrasion, grinding away of rock by
transported particles

22. 3) water dissolves chemical elements in the
rock (changes composition of rock)

23. When a river enters an ocean, the sediment
is deposited in a fan-like landform

24. Mississippi River Delta

25. Waves on a coastline may also change the
land
Waves can reduce or increase beaches
Sediment from waves may build up sand bars
or islands

28. Double trouble
Dana Goegelman looks over the
damage and erosion to the beach
beside her parents hotel in
Indiatlantic, on Tuesday, Sept. 28,
2004. The Casablanca Inn was
damaged by Hurricane Frances
and then later lost much of its
beach and walkway to erosion
when Hurricane Jeanne pounded
the Florida coast on Sunday. (AP/
Dave Martin / September 28,
2004)

29. loess (LOH•uhs)
windblown silt and clay sediment that produce very
fertile soil
silt – fine sand carried by moving water

30. A typical loess exposure in
southern Illinois

31. The Mississippi River Valley in the U.S. and
grasslands of Argentina have extensive
amounts of loess.

32. May produce new landforms (sand dunes)
Similar to water erosion, the wind transports
and deposits sediments in other locations

37. glaciers
large, long-lasting mass of ice
move because of gravity
form in mountainous areas
form in heavy snowfall regions

42. the changing of landforms by slowly moving
glaciers
Erosion occurs when glaciers move

43. When glaciers move, they carry rocks with
them
Rocks left behind by a glacier may form a hill
or ridge called a moraine

44. Who you callin’ a
moraine!?

46. Different kinds of moraines on and near Gornergletscher, Valais,
Switzerland: 1 - lateral moraines, 2 - middle moraines, 3 - terminal
moraine (this moraine was deposited during the Little Ice age by the
small cirque glacier of which two remnants remain, above and above
left of the letter "3".

47. hyoo-muhs

the organic material in soil

48. humus

49. 1) parent material
2) relief
3) organisms
4) climate
5) time

50. The variety of soils – and the climates in
which they’re found – determine what can
grow there.