Download Topic 14 – Landscape Development and Environmental Change

Topic 14 – Landscape Development and
Environmental Change
Landscapes, or topography are the features of the Earth’s
surface.
There are Four main ways to characterize a landscape:
1) Slope (gradient) of the land
2) Shape of the landscape features
3) Soil properties
4) Stream drainage patterns
Slope (gradient) of the Land
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Remember if you have a steep slope, there will
be less deposition of particles there.
If water flows over the steep slope (gradient), it
will flow faster causing more weathering and
erosion
The slope of the land can be measured using the
gradient equation on the front cover of your
ESRT
gradient = change in field value
distance
Shape of the Landscape
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Landscapes are divided into three major
types
1) mountains (highlands)
 2) plateaus (uplands)
 3) plains (lowlands)
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A mountain is an area of high elevation, compared to the
surrounding area or sea level. Its peak is usually
thousands of feet higher than its base. They usually are
characterized by distorted rock structures with faults,
folds or volcanic rocks because they are usually
composed of metamorphic and volcanic rocks.
Cont. Shape of the Landscape
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A plateau is also an area of high elevation,
but it has undistorted (sedimentary)
horizontal rock structure and often a more
level slope or gradient.
It may have steep sides if they have been
eroded by a glacier or stream.
Ex: Colorado Plateau in CO, Catskill
Plateau in NY
Cont. Shape of the Landscape
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A plain is usually composed of
sedimentary rocks, has a low elevation
and generally a flat/level surface with little
slope.
Ex: Atlantic Coastal Plain of Long
Island, NY
You can see the Landscape Region of New
York on page 2 of your ESRT.
Factors of landscape development
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Two groups of forces can change
landscapes:
1) uplifting forces
2) the leveling or destructional forces
 Uplifting forces originate beneath the
Earth’s surface. They displace the rock
and raise the land, where mountains can
be built. This can be done by volcanoes,
earthquakes – energy is gained from the
convection currents in the mantle.
Factors of landscape development
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Leveling forces occur near the Earth’s surface.
The land is leveled and lowered by breaking
down rocks and transporting them elsewhere
(erosion).
The erosional systems can be running water,
wind, glaciers, gravity or shoreline processes.
The landscape process has stages: youth,
maturity and old age. In youth, uplifting forces
take place. In maturity, leveling forces take
place and in old age, leveling forces are still
dominant but less effective.
Cont. Factors of landscape
development
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Glaciers affect landscapes also and evidence
from the last ice age (Pleistocene) can bee seen.
Some features of glacial erosion and deposition.
include:
1) mountaintops and steep slopes without
much soil
2) soils with large range of particle size
3) wide U-shaped valleys
4) many lakes (finger lakes)
5) many small hills (drumlins or moraines)
6) parallel scratches on bedrock
How does climate affect Landscape
Development
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The rate at which landscape development occurs is
dependent on temperature and moisture
In dry/arid climate – there is little vegetation so
sediments do not stay in place on steep slopes, so
they get rapidly carried away. This allows an arid
climate to have steep slopes and sharp angular
features with sand dunes and sandblasted bedrock.
 Ex: Southwestern US
In wet/humid climates – sediments will hold better
on steeper slopes, so the landscape is typically
smoother and has more rounded features.
 Eastern US
Soil properties
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Looking at the soil’s permeability, porosity,
particle size, etc is important.
The climate affects the soil that covers the
bedrock
1) Arid climates – thin soil coverings
2) Humid climates – thick and full of
organic soil coverings.
Drainage Patterns
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The drainage pattern (way in which water will flow) is
mainly determined because of the resistance and
structure of the underlying rock.
In horizontal layers, streams will develop a random
pattern
If there are structures like folding and faulting, the
rocks will control the directions of stream flow.
Some bedrock structures are:
 Escarpments (cliffs) along the edge of resistant
layers
 Ridges (narrow uplands) formed from resistant
rocks in the Hudson-Mohawk Lowlands is SE New
York.