Transcript arthe28099s-changing-surface-week-3-term-3

Earth’s changing surface
Book “G” chapter 1 page 4
Section 1 page 6
exploring Earths surface
• Topography: the shape of the land
determined by elevation, relief, and
landforms.
– Examples: what is the topography where our
school sits? what is it where your house is? Is
it all the same?
Elevation
• Elevation: The height above sea level of a
point on earth.
– Sea level: is where we start at zero. Then we
go up from there.
– Why sea level ? What makes sea level so
universal
– What measurements do we use when talking
about elevation?
• Feet
Relief
• Relief :the difference in elevation between
the highest and lowest parts of an area.
– Low relief = low rolling hill measured agents
flat plains.
– High relief = rocky mountains measured
agents valleys.
Landforms
• Landforms : a feature of topography
formed by the processes that shape
Earths surface.
– Mountains
– plateaus
– Plains
– Oceans, rivers
Mountains
• Mountains : a landform with high elevation
and high relief.
– Mountain range : a group of mountains
closely related in shape, structure, and age.
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Rocky mountains
Sierra Nevada mountains
Himalaya mountains
Wasatch mountains
Plains
• Plains : is a landform that is made up of
nearly flat or gently rolling land with low
relief.
– Coastal plains
• Along the Eastern and Western coastlines of the
U.S.
– Great plains
• In the middle of the U.S. from Oklahoma and
Texas to Canada.
Plateaus
• Plateaus : a landform that has high
elevation and more or less level surface.
– These are rarely flat and smooth, there are
usually rivers and streams that cut into the
surface.
Earth Models
• Earth models are used to show the earth
in a scale in the forms of maps and
globes.
Maps
• Map: a flat model of all or part of the
Earths surface as seen from above.
– Scale: relates distance on a map to a distance
on the Earths surface. Scale is often given as
a ratio.
• Example: one unit on a map could equal 25,000
units on the ground. So one centimeter on the map
would equal 0.25 of a km on the ground.
Key’s & legends
• Map makers use keys and legends to help
the reader of the map understand the
symbols used on the map and what they
mean.
• Now lets see what it is I’m talking about.
Globes
• Globes : is a sphere the represents the
Earths entire surface.
– The advantage of a globe is that it can
accurately represent the Earth in relative
scale because its round.
– A map is flat so it looses some of the
proportions.
Measuring in Degrees
• We are not talking about tempature.
– The Earth is dived into equal degrees.
• How many degrees is it divided into?
– 360
• To locate positions on the Earth’s surface
scientists use units called degrees. These units are
quiet large to make precise measurements.
– So we came up with smaller units does anybody know
what they are.
» Degrees are divide up into minutes and seconds.
Divided in half?
• Now that we have the Earth divided into
equal segments what's left?
– There are two way the earth is divided in half
who knows what they are?
• The Equator
– Is an imaginary line that circles Earth half way between
the North and South poles.
• Prime Meridian
– Is an imaginary line that makes a half circle from the
North pole to the South pole and passes through
Greenwich ,England
There’s More
• Now that we have 360 degrees that
equally divides that Earth, minutes and
seconds that give us a precise way to
locate something on a large globe. An
equator and prim meridian that separated
the North, South, East, West from Each
other. What else could we possibly need?
From top to bottom
• Latitude : The
distance in degrees
North or South of the
Equator.
– Were do you start?
• The equator and its
degree is 0
– Between the equator
and each pole are 90
evenly spaced
degrees. Each one is
equal to 111 km
From side to side
• Longitude : the
distance in degrees
East or West of the
Prime meridian.
– Were do we start?
• prime meridian
– There are 360 lines
that run North and
South and meet at the
poles. Each degree
represents about 111
km at the equator.
Topographic maps
• A topographic map: is a map showing the
surface features of an area.
– Topographic maps use symbols to portray the
land as if you were looking down at it from
above. Map makes use contour lines to
represent elevation, relief , and slope on the
map.
• the unit of measurement are feet in the U.S. other
places use meters.
– Are they useful?
» Vary useful for hunting, hiking, building, mining, ect.
Chapter 2 weathering and soil
formation.
• What is weathering?
– Weathering is : The chemical and physical
process that break down rocks at the Earth’s
surface.
• Where does soil come from?
– Rocks being broken down over long periods of time. Ice
and heat play a huge role in weathering
» Time to do the marble experiment. How do you
crack a glass marble?
There are two types
• What are the two types of weathering?
– Mechanical weathering: Is when rock is
physical broken into smaller pieces.
• This type of weathering doesn’t change the
composition of the rock. Its like hitting a rock with a
hammer, the rock is smaller but its still the same
as it was before.
– Examples of this would be rocks in plies below an
outcrop, smaller pieces have been broken off.
Types of weathering continued
• The other type is?
– Chemical weathering: this brakes down rock
through chemical changes.
• These process include the actions of water,
oxygen, carbon dioxide, living organisms, and acid
rain.
– Mechanical and chemical weather usually work together.
Chemical weathering produced holes in the rock that
makes it easier to break into small pieces which creates
more surface area which allows chemical weathering to
act faster.
WICH OF THESE IS THE MOST
IMPORTANT?
• There are five ways that chemical
weathering can occur. But which one is
the most IMPORTANT?
– Water : water is by far the most important.
Water dissolves rock and that allows the
“stuff” to mix with the water making a solution.
– The others play important parts but water is
the most important .
The finished product
• So what do we have after chemical
weathering?
– For example: granite contains many different
elements and minerals some of these are
feldspar, quarts and mica.
• As a result of chemical weathering feldspar
changes into clay minerals. That’s why our valley
here has so much clay because our mountain’s are
granite.
• TIME FOR THE FIZZING ANTACID
EXPERIMENT
Erosion
• Now that the rocks are broken up and
made smaller by weathering how do we
move them?
– Erosion: the process by which water, ice,
wind, or gravity moves weathered rock and
soil.
• This is how the rocks are moved from the
mountain down to the valley
Rate of weathering
• What is rate?
– Is the time it takes or the speed at which
something occurs.
• What are the two things that can effect
rate?
– Type of rock
• If the rock is vary hard or vary soft this will effect
the rate
– Climate
• If the climate is wet or dry this will effect the rate.
Section 2 how soils form.
• First we need to know what soil is.
– Soil : is the loose weathered material on
Earths surface in which plants can grow.
• This is what rocks end up as after weathering and
erosion. Soil is a mixture of rock particles,
minerals, decayed organic material, water, and air.
– Humus is a very important part of a soil it is a dark
colored substance that forms as plant and animal
remains decay. This is what makes soil fertil.
• There are two part to the soil level top soil and sub
soil.
Soil conservation
• What is soil conservation?
– The ability to keep soil from being lost due to
erosion forces.
• Why is this important?
– Because everything on land depends directly or indirectly
on soil.
» Plants
» Animals that eat plants.
» Animals that eat animal that eat plants.
– Ways to keep soil include reducing erosion by
increasing plants, diverting rivers, proper land
management techniques
Chapter 3 Erosion and Deposition
• We know what erosion is, but what is
deposition?
– Deposition : Is the process in which sediment
id deposited or laid down in a new location.
– Sediment : may consist of pieces of rock or
soil or the remains of plants and animals.
• What force is the major player in this process?
– Gravity
» Gravity causes the movement of sediment and
causes it to be laid down, it can also cause mass
movement of sediment.
Mass movement
There are different types of mass movement
and they include landslides, mudflows,
slumps, and creeps.
which of these do you think is the most
destructive?
landslides.
Landslides
• Landslide: occurs when rock and soil slide
quickly down a steep slope.
– Why do landslides happen?
• There are many reasons why, Earth quakes,
cutting into a hill. When vegetation is removed by
fire or grazing.
Landslide pic
MUDFLOW
• Mudflow : is the rapid downhill movement
of water, rocks, and soil.
– Mudflow happen all of the time Earth quakes
can set them off, as well as a light rain.
– It all depends on how saturated the soil is.
Mudflow pics
Slumps
• Slump: a mass of rock and soil suddenly
slips down a slope.
– Unlike a landslide a slump is when material
suddenly moves in one large mass.
Slump pic
Creep
• Creep : is a very slow downhill movement
of rock and soil. It can even occur on
gentle slopes.
– what do thing causes soil to creep?
• Usally is happens from freezing and thawing in
water of cracked layers of rock beneath the soil.
– It happens so slow that you cont really see it happen
while you are watching it. Like a flower opening, but over
time you can see the effect , on telephone poles, fence
posts, and grave stones.
Water Erosion
• Moving water is the major agent of erosion
that has shaped the Earths surface since
water has been on land.
– Water erosion includes spring runoff, rivers,
streams, lakes, rain, snow, Ice,
• All of this water, has to go somewhere. What do
we call it?
– Flood plain: the flat\ wide area of land along a river.
» All of the water on earth that comes from the different
types of precipitation end up in rivers streams, and
then in some form of a stable body of water. Oceans,
lakes and reservoirs.
Flood plain
Water Erosion continued
• The water carries sediments in it and
deposits these sediments in the flood
plain, and deltas of the body of water.
– How dose this impact us?
• Who knows what they want to do to lake Powell?
– They want to drain it because they say its filling up with
sediment form the Colorado river.
• Look at the picture on pages 78-79 in book
“G” of your science book.
Deltas
Ground water Erosion
• When rain and snow fall not all of
evaporates or runs off into the rivers and
streams. A lot of it goes directly into the
ground.
– Ground water: is water the fills the cracks and
spaces in underground soil and rock layers.
• What effect can this have?
– When water enters the ground it combines with CO2 to
form carbonic acid. This acid can dissolve limestone,
which over long period of time can result in underground
caves.
» It can also have other effects, when there is a
drought , the soil will absorb water instead of
Glaciers
• Our continent has had a lot of influence
from glaciers. Glaciers created the great
lakes. They smoothed out the great plains,
and here in our stat they carved out many
of our canyons. All of the large granite
boulders that you see at the entrance of
the canyons were moved there by glaciers
– Glacier : is ant large mass of ice that moves
slowly over land.
Two types of glacires
• Continental glaciers : is a glacier that
covers much of a continent or large island.
• Valley glaciers: is a long, narrow glacier
that forms when snow and ice build up
high in a mountain valley.
– How do glaciers form?
• High in mountain valleys temperatures seldom rise
above freezing. Snow build up year after year, and
the weight compact everything at the bottom into
ice. When its big enough gravity pulls it downhill.
– Glaciers can only form in an area where more snow falls
than melts.
Waves
• How are waves formed?
– Wind ; some of the energy from wind is
transferred to the water creating waves.
• Waves are the major force of erosion along the
coastline. Waves shape the coast through the
constant pounding of water; breaking down rock
and transporting sand and other sediment.
– Where do beaches come from.
• As waves reach the shore, they drop the sediment
they carry forming a beach.
– Beach : is an area of wave- washed sediment along the
coast.
Wind
• How does wind cause erosion?
– Wind causes erosion by deflation and
abrasion.
• The main way wind causes erosion is by deflation.
– Deflation : wind erosion that removed surface material
• The other way is abrasion
– Abrasion :the grinding away of rock by other rock
particles carried in water, ice, or wind.
» Wind can carry sediments across the oceans. And
create an entirely new place in the desert in the form
of sand dunes.