Slide 2 Slide 3 Land has many different shapes. A natural land
shape or feature is called a landform. When you describe the
landforms around your town you are describing topography.
Topography is all the kinds of different landform in a certain
area. Slide 4 These are the Rocky Mountains. This is a tall, jagged
peak mountain that rises thousands of feet above the Surrounding
land. Slide 5 The Appalachian Mountains in this picture are lower
and more rounded. They are still thousands of feet tall, but are
much lower than the rocky mountains. Slide 6 So even though the two
mountain areas are very similar landforms, their topographies are
very different! Slide 7 The topography of volcanoes differs in
another way. Volcanoes usually occur as individual mountains, not
in ranges. They may have steep sides or rounded slopes. Slide 8
Hills are landforms that are like mountains, but not as high. Most
hills have rounded slopes. Slide 9 Not all landforms have slopes. A
plain is a large, flat landform with little relief. Relief is the
difference in elevation between high and low places. Slide 10
Glaciers are large sheets of ice. As they move, they change the
land beneath and around them. Moraines are long, low hills formed
by glaciers. Slide 11 As moving ice scrapes the land beneath it,
rocks and other materials are picked up and carried away. This
material is deposited somewhere else, when the glacier melts. Slide
12 Q. How can you tell a moraine from a hill Moraines have rock,
sand, and clay. These things are deposited together. Other
landforms made by glaciers are glacial grooves. Glacial grooves are
scrapes and scratches in the rock made as the glacier moves along
land. Slide 13 Landforms of sand are easily shaped by wind and
water. These landforms are known as sand dunes. Wind can change a
sand dunes shape or even its entire location. Sand dunes can move
as much as 100 ft. in one year. Slide 14 Water also reshapes
beaches, forming barrier islands and san spits extending out into
the water from the ends of many islands. Sand spits and barrier
islands are long, narrow piles of sand that help protect the
mainland from the wave erosion. Slide 15 A mesa is a tall,
flat-topped rock feature, that forms when water and wind erodes the
surrounding rock. Canyons are deep valleys with steep sides. They
are found throughout the Southwest. The water and wind has carved
the land away. The Grand Canyon is an example. Slide 16 P. 255
Slide 17 Slide 18 Over time, sand wears away rock by breaking it
into smaller pieces. This process is known as weathering. Step 1:
Weathered rock (sand) is carried away by wind. Step 2: The pieces
keep moving as long as the wind is blowing. Step 3: The wind stops
and the sand falls to the ground. Step 4: These piles grow. Step 5:
They slowly become sand dunes. Slide 19 Are found in many places:
deserts, beaches, lakeshores, etc. Some desert dunes are as high as
a 30-story building. All dunes help protect land during storms.
However, dunes can cause damage to buildings and roads if pushed by
strong winds. Slide 20 Moving water can change Earths surface by
carrying soil and small pieces of rock away from landforms. Moving
water can dig a canyon or change the path of a river. A rapidly
flowing river erodes its banks and its bottom. Eroding banks makes
the river wider. Eroding the bottom makes the river deeper. Slide
21 The moving water then carries sediment downstream. When the
water slows down, sediment is deposited. Deposits on a river bank,
makes it narrower. Deposits in the bottom make the river shallower.
Slide 22 Moving wind and water has energy. The faster it moves, the
more energy it has. But, all moving water, even a gentle rain, can
erode some sediment. When rain falls on bare soil, it splashes away
soil. As it runs downhill, it gains speed and energy. Over time,
water erosion can leave gullies, or ditches in the ground. Slide 23
Ocean waves also cause erosion. Waves carry away broken bits of
rock and sand. Piece by piece, cliffs get steeper. When cliffs
eventually overhang, the entire cliff can collapse into the oceans.
Slide 24 Ocean waves change landforms in another way, also. Each
wave also brings more sand to the beach. This is deposition. As the
water slows down, it loses energy and the larger pieces of sediment
fall out and settle to the bottom. Slide 25 Flooding can deposit
sediment near a river. When you have heavy rains, rivers flood
their banks. When the rain stops, the water returns, but the
sediment it carried is deposited on the land. This sediment is rich
in nutrients for plants. These areas are called flood plains and
are great for farmers, but awful for living. Slide 26 Rivers
deposit sediment at the mouth, the place where it empties into the
ocean. The flow of water slows as the river reaches the ocean. Much
sediment is deposited, forming a delta. A delta is an area of new
land at the mouth of the river. Slide 27 Ground water can weather
and erode soft rocks. Underground erosion causes caves to form. If
the roof of the cave collapses, under the weight, it creates a
large hole. These holes are Sink Holes. Most sinkholes are found
where limestone is common. Slide 28 Gravity also helps
land-changing processes to occur. Landslides happen very suddenly,
especially after heavy rains or earthquakes. A land slide is when
soil, mud, and rock move quickly down a slope. Slide 29 Ice can
change landforms by weathering rocks. Rocks have tiny cracks and
holes When it rains, these fill with water. If it is cold the water
freezes, and expands, making cracks bigger. The next time it rains,
more water gets in, and the process continues. Over time, the rocks
are broken into smaller pieces, until there is only a pile of sand.
Slide 30 Ice can also change landforms as glaciers. Glaciers can
shape landforms by erosion and deposition. Glaciers follow river
valleys down a mountain. As a glacier moves, it changes the
V-shaped valley into a U-shaped valley. Glaciers deposit the
sediment when they melt. New York is an island formed from the
deposition of a glacier. Slide 31 Plants can cause weathering and
erosion. When a seed germinates on a rock, the roots grow in small
cracks. As the roots grow they cause the cracks to grow. Some
plants even release chemicals into the soil. These chemicals help
weather rock by dissolving certain minerals. Slide 32 Plants also
preserve and protect Earths landforms. Roots hold soil and sand in
place, and prevent erosion by wind and water. Farmers often plant
cover crops, to help return nutrients to the soil and stop erosion.
At the beaches, plans keep sand dunes from blowing away. Slide 33
P.265 Slide 34 Slide 35 The center of the Earth is 4000 miles down.
The Earth has 4 layers- 1. crust 2. mantle 3. outer core 4. inner
core. Slide 36 The Crust is solid rock. The Mantle is also a lot of
solid rock, but there is also soft rock, like melted candy. The
Outer Core is liquid iron (not rock), and is liquid. The Inner Core
is iron and nickel, and is solid due to great pressure. Slide 37
The Earths crust is divided into plates. Plates are puzzle pieces
that fit together. There are 10 major plates. Plates float on the
mantle. As the rock flows, the plates move. This causes changes in
the Earth. Slide 38 When 2 plates move past each other, energy is
released and the ground shakes. An earthquake is movement of the
ground caused by a sudden release of energy in Earths crust. Slide
39 The place within the crust where the energy is released is
called the focus. The greatest damage will occur directly above the
focus. The point on the Earths surface that is directly above the
focus is called the epicenter. Earth quakes are caused by 3 types
of plate movement: 1. plates pushing together 2.plates sliding past
each other 3. plates pulling apart Slide 40 Earthquakes occur along
a fault, or break in the crust. Most faults are found near the
edges of plates. Faults develop as plate movement bends and cracks
the crust. Earthquakes caused by pushing plates are strong.
Earthquakes caused by pulling plates are weak. Earthquakes are
measured by their magnitude, or amount of energy released. It is
reported on the Richter Scale. Slide 41 An earthquake measuring 2.0
is too small to be felt. An earthquake measuring 6.0 or more can
cause a lot of damage. Slide 42 Melted rock beneath the surface of
the Earth is magma. Magma forms in places where plates push against
or pull away from each other. Magma is less dense than solid rock,
so it pushes upward. A vent is an opening in the crust where magma
can come out. When magma reaches the air, it is called lava. A
volcano is a mountain made of lava, ash, or other materials from
eruptions. Slide 43 Composite Volcanoes- wide with steep slopes.
Made of alternating layers of lava and ash. (Mt. St. Helens) Shield
Volcanoes-broad with gentle slopes. Form from lava that easily
vents. (Hawaiian Islands) Cinder Cone Volcanoes- tall and narrow,
steep slopes. Made of rock, ash and other materials. Are not made
of lava. (Paricutin) Slide 44 Mountains are the tallest landforms.
They form where the crust is crumpled and pushed up. The edge of
the denser plate sinks, and the less dense plate pushes up. If they
are the same density they both push up.
