Steep slopes, lack of vegetation, and heavy rains are detrimental to topsoil. Every time it rains, water hits the ground with surprising force, causing some of the soil to wash away with the water. The soil particles, or sediments, are deposited elsewhere.Physical weathering is the breakdown of the rock without changing its composition. Examples of mechanical weathering include frost wedging (water freezes in cracks and expands to break up the rock), exfoliation (top layer is removed due to severe weather), root wedging (plant roots grow into rocks and break them), abrasion (wind and water break down rocks),

1. Four Areas of Earth Science
Illustrated by Kella Randolph
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2. Astronomy
• Astronomy is the study of bodies in space, such as stars, planets, and the
universe.
This Photo by Unknown Author is licensed under CC BYThis Photo by Unknown Author is licensed under CC BY-SA

3. Meteorology
• Meteorology is the study of weather and includes all concepts
related to weather and climate.
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USA_weather_forecast_2006-11-07.gif https://yourcruisingeditor.files.wordpress.com/2011/02/cyclones-over-aus_bureau-of-meteorology.jpg

4. Geology • Geology is the study of Earth, which includes rocks, soil, and geohazards
such as volcanoes.
https://opentextbc.ca/geology/wp-content/uploads/sites/110/2015/08/Geologists-examining-ash-layer.jpg https://adventuresingeology.files.wordpress.com/2011/06/image41.jpg

5. Hydrology
• Hydrology/Oceanography is the study of water, which includes all
fresh and saltwater processes. Humans and other land dwelling animals
cannot drink seawater. We must have freshwater to survive. Only about
2.5% of all the water on Earth is freshwater.
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content/uploads/2016/02/WaterSupplySources_StyleA.png
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https://utexaslearn.instructure.com/courses/2010099/pages/explain-
ii-water-resources-and-use

6. Types of rock
• Sedimentary
• Igneous
• Metamorphic
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7. Sedimentary rock • Sedimentary rocks are formed from compacted
sediments. When other types of rocks undergo
weathering, they turn into sediments and can then
become sedimentary rocks.
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Triassic_Utah.JPG

8. Igneous Rock
• Igneous rocks form near or on the surface and are made from cooled lava. They
tend to be shiny/glassy in appearance. Igneous rocks can be turned into
sedimentary or metamorphic rocks depending on environmental conditions.
https://openpress.usask.ca/app/uploads/sites/29/2018/06/volcanic_rock_ID_3rd.png
https://opentextbc.ca/physicalgeologyearle/wp-content/uploads/sites/145/2016/06/magma2.jpg

9. Metamorphic rock
• Metamorphic rocks are formed deep within the earth by being subjected
to intense heat and pressure. These can then melt into magma and become
igneous rocks or they can be weathered into sediment and transform back
into sedimentary rocks. It is important to understand that these changes take
a very long time.
https://upload.wikimedia.org/wikipedia/commons/thumb/8/8e/Rock_contact_metamorphism
_eng_big_text.jpg/220px-Rock_contact_metamorphism_eng_big_text.jpg
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10. Types of Weathering
Mechanical/Physical Weathering
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11. Chemical
weathering
• Chemical weathering involves changing the chemical makeup of the rock.
This can be done through dissolving (acid rain or water can break down the
rock), carbonation (acid made from carbon dioxide and water can break down
the rock), or oxidation (minerals in the rock mixing with oxygen).
https://farm6.staticflickr.com/5031/5837350062_b112556080_z.jpghttps://upload.wikimedia.org/wikipedia/commons/thumb/b/ba/Salt_weathering_in_gozo.jpg/500px-
Salt_weathering_in_gozo.jpg
https://upload.wikimedia.org/wikipedia/commons/thumb/6/6d/Lava_z14.jpg/220px
-Lava_z14.jpg

12. Physical
weathering
• Physical weathering is the breakdown of the rock without changing its
composition. Examples of mechanical weathering include frost wedging (water
freezes in cracks and expands to break up the rock), exfoliation (top layer is
removed due to severe weather), root wedging (plant roots grow into rocks
and break them), abrasion (wind and water break down rocks), and animal
activity (burrowing animals or human activity).
https://live.staticflickr.com/4766/39083969255_991cf7b369_b.jpg

13. Which type of weathering?
Mechanical/physical weathering - physical disintegration of a rock into
smaller fragments, each with the same properties as the original.
Occurs mainly by temperature and pressure changes
• frost wedging: water from rain or snow fills a crack in a
rock. Then the water freezes and expands. The expansion
breaks the rock.
• root wedging: a plant grows in a crack in a rock and as it
grows, it breaks the rock
• Exfoliation occurs when rocks that formed in high pressure
environments are brought to the Earth's surface. When the
pressure on these rocks decreases, they expand and split
apart into sheets.
• Abrasion is caused when rocks rub together. For example,
the rocks on a riverbed smooth each other because they
collide in the current. Small particles of rock carried by the
wind may cause abrasion as well.
• Thermal expansion is caused by heating. When rocks are
heated -- as by the sun -- they expand. If different portions
of a rock expand at different rates, the heated parts will
exert pressure on each other, and crack.
Chemical weathering - process by which the internal structure of a
mineral is altered by the addition or removal of elements.
• Oxidation is the reaction of oxygen with chemicals in a rock. For
instance, oxygen reacts with iron to form iron oxide -- rust --
which is soft and vulnerable to physical weathering.
• Hydrolysis is a process in which a rock absorbs water into its
chemical structure. A rock with a higher water content is softer,
and thus easier for physical weathering, or even just gravity, to
decay.
• Carbonation is caused by carbonic acid in water reacting with and
degrading rock. This acid is especially effective at degrading
limestone. Underground carbonation may form limestone
caverns.
• Acid rain is caused by sulfur and nitrogen compounds in the air
reacting with water to form acids that then fall to the ground.
These acids are particularly harmful to marble, chalk, and
limestone, and cause damage to tombstones, statues, and other
public monuments.
Zamboni, Jon. "Difference Between Chemical and Physical Weathering" sciencing.com, https://sciencing.com/difference-
between-chemical-physical-weathering-5827944.html. 30 December 2019.

14. Erosion
• Erosion breaks down material, such as soil, and transports it
to other places. Water is one of the main agents of
erosion. Every time it rains, water hits the ground with
surprising force, causing some of the soil to wash away with the
water. The soil particles, or sediments, are deposited elsewhere.
https://upload.wikimedia.org/wikipedia/commons/c/c7/Sidari_Eroded_Rock.jpg
http://www.soil-net.com/album/Water/Lakes_Rivers/slides/River%20Swale%20bank%20erosion.jpg

15. Human activities that
can lead to erosion
• 1. Deforestation: removing all
of the trees from an area
• 2. Agriculture: clearing away
forest and native growth to
make room for food or textile
crops to grow
• 3. Construction: clearing land to
use for buildings and roads
https://southafricatoday.net/wp-content/uploads/2018/07/Deforestation-inside-Sudcams-concession-in-Cameroon.jpg

16. Lack of vegetation
can lead to erosion
• Without roots to hold down
the soil, the wind can easily
remove the topsoil, resulting in a
dust storm. We can help solve
this problem by building
windbreaks, planting grasses in
the non-growing season, and
terracing hillsides when using
them for agriculture.
https://upload.wikimedia.org/wikipedia/commons/thumb/b/ba/Morroco-arid-climate.jpg/220px-Morroco-arid-climate.jpg

17. Steep slopes can lead
to erosion
• Steep slopes, lack of vegetation, and heavy rains are detrimental to
topsoil. Every time it rains, water hits the ground with surprising force,
causing some of the soil to wash away with the water. The soil particles,
or sediments, are deposited elsewhere.
https://www.qld.gov.au/__data/assets/image/0023/64841/mass-movement.jpghttps://upload.wikimedia.org/wikipedia/commons/thumb/6/6e/Issehoved_set_fr
a_havet.JPG/220px-Issehoved_set_fra_havet.JPG
https://mronline.org/wp-content/uploads/2019/04/Fields-on-steep-slopes.jpg

18. We can help prevent
erosion in these four
ways:
a. terracing hillsides when using them for agriculture
b. Building retaining walls
c. building windbreaks
d. planting grasses in the non-growing season
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ne_Retaining_wall.jpg/270px-Stone_Retaining_wall.jpg
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ak_trees_at_Methwold_Common_-_geograph.org.uk_-
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19. Sinkholes
• Sinkholes form when acidic rainwater falls to the ground and
creates a sinkhole by dissolving the limestone beneath the soil.
• Human mistakes can also create sinkholes. When an
underground water pipe is leaking over a long period of time, it
washes away the soil around the hole in the pipe. Over time, the
hole beneath the surface expands and eventually the soil collapses
and falls into the sinkhole.
The front of a city bus is up in the air after a sinkhole opened under it during
rush hour in downtown Pittsburgh.
https://images.app.goo.gl/uoPi8o19m9azphPc9https://c1.staticflickr.com/1/325/18050124324_b43e965017_b.jpg