5.7B: Changes to Land (R)
Concept
Exploration
Earth and Space
Sea Arch
A sea arch often forms where cliffs meet the
sea. It is often a former cave. It is usually made
of harder rock on top and softer rock such as
limestone on bottom. When the bottom rock is
softer it will erode away faster. Waves pound
against the rock, weathering it down and
eroding it to form the arch.
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5.7B: Changes to Land (R)
Concept
Exploration
Earth and Space
River Delta
A delta is formed at the mouth of a river where
the river flows into another body of water. The
river’s current picks up and carries sediments to
the mouth of the river. When the current slows
down the sediment is deposited. As more and
more sediment is deposited, land will begin to
build up. Most deltas form a triangular shaped
land mass.
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2
5.7B: Changes to Land (R)
Concept
Exploration
Earth and Space
Sand Dune
Sand dunes can be found along coasts, along a
dried up lake or river bed, or an open sandy
area with little vegetation. They are formed by
wind moving loose sand until it is stopped by an
obstacle which could be a rock or a tree.
Vegetation growing in the sand dunes can help
anchor the dunes.
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5.7B: Changes to Land (R)
Concept
Exploration
Earth and Space
Canyon
A canyon is usually formed by a river cutting
through layers of rock over a long period of
time. They form in dry areas where there is less
vegetation to prevent erosion. Wind and water
work together to chip away at the canyon walls
and carry the sediments away.
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5.7B: Changes to Land (R)
Concept
Exploration
Earth and Space
Butte
A butte is a landform that usually has a flat top
and straight vertical sides. The flat top, or cap
rock, is hardened lava that does not easily
erode. The lower layers are made up of
sedimentary rock layers. Dry winds and abrasive
materials, as well as water, erode the sides of
the butte. Rock material that has eroded from
the sides falls downward forming the sloping
base.
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