Topic 14 – Landscape Development and Topic 14 – Landscape Development and Environmental ChangeEnvironmental Change

Landscapes, or topography are the features of the Landscapes, or topography are the features of the Earth’s surface. Earth’s surface.

There are Four main ways to characterize a There are Four main ways to characterize a landscape:landscape:

1) Slope (gradient) of the land1) Slope (gradient) of the land

2) Shape of the landscape features2) Shape of the landscape features

3) Soil properties3) Soil properties

4) Stream drainage patterns4) Stream drainage patterns

Slope (gradient) of the LandSlope (gradient) of the Land Remember if you have a steep slope, there Remember if you have a steep slope, there

will be less deposition of particles there.will be less deposition of particles there. If water flows over the steep slope If water flows over the steep slope

(gradient), it will flow faster causing more (gradient), it will flow faster causing more weathering and erosionweathering and erosion

The slope of the land can be measured The slope of the land can be measured using the gradient equation on the front using the gradient equation on the front cover of your ESRTcover of your ESRT

gradient = gradient = change in field valuechange in field value

distancedistance

Shape of the LandscapeShape of the Landscape Landscapes are divided into three Landscapes are divided into three

major typesmajor types 1) mountains1) mountains 2) plateaus2) plateaus 3) plains3) plains

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 LandscapeCont. Shape of the Landscape

A plateau is also an area of high A plateau is also an area of high elevation, but it has undistorted elevation, but it has undistorted horizontal rock structure and often a horizontal rock structure and often a more level slope or gradient. more level slope or gradient.

It may have steep sides if they have It may have steep sides if they have been eroded by a glacier or stream.been eroded by a glacier or stream.

Ex: Colorado Plateau in CO, Ex: Colorado Plateau in CO, Catskill Catskill Plateau in NYPlateau in NY

Cont. Shape of the LandscapeCont. Shape of the Landscape

A plain is usually composed of A plain is usually composed of sedimentary rocks, has a low sedimentary rocks, has a low elevation and generally a flat/level elevation and generally a flat/level surface with little slope.surface with little slope.

Ex: Atlantic Coastal Plain of Long Ex: Atlantic Coastal Plain of Long Island, NYIsland, NY

You can see the Landscape Region of You can see the Landscape Region of New York on page 2 of your ESRT.New York on page 2 of your ESRT.

Factors of landscape Factors of landscape developmentdevelopment

Two groups of forces can change Two groups of forces can change landscapes:landscapes:

1) uplifting forces1) uplifting forces2) the leveling or destructional 2) the leveling or destructional

forcesforces

Uplifting forces originate beneath the Uplifting forces originate beneath the Earth’s surface. They displace the rock Earth’s surface. They displace the rock and raise the land, where mountains can and raise the land, where mountains can be built. This can be done by volcanoes, be built. This can be done by volcanoes, earthquakes – energy is gained from the earthquakes – energy is gained from the convection currents in the mantle.convection currents in the mantle.

Factors of landscape Factors of landscape developmentdevelopment

Leveling forces occur near the Earth’s Leveling forces occur near the Earth’s surface. The land is leveled and lowered surface. The land is leveled and lowered by breaking down rocks and transporting by breaking down rocks and transporting them elsewhere (erosion).them elsewhere (erosion).

The erosional systems can be running The erosional systems can be running water, wind, glaciers, gravity or shoreline water, wind, glaciers, gravity or shoreline processes.processes.

The landscape process has stages: youth, The landscape process has stages: youth, maturity and old age. In youth, uplifting maturity and old age. In youth, uplifting forces take place. In maturity, leveling forces take place. In maturity, leveling forces take place and in old age, leveling forces take place and in old age, leveling forces are still dominant but less effective.forces are still dominant but less effective.

Cont. Factors of landscape Cont. Factors of landscape developmentdevelopment

Glaciers affect landscapes also and evidence Glaciers affect landscapes also and evidence from the last ice age (Pleistocene) can bee from the last ice age (Pleistocene) can bee seen. seen.

Some features of glacial erosion and deposition.Some features of glacial erosion and deposition.include:include:

1) mountaintops and steep slopes without 1) mountaintops and steep slopes without much soil much soil2) soils with large range of particle size2) soils with large range of particle size3) wide U-shaped valleys3) wide U-shaped valleys4) many lakes (finger lakes)4) many lakes (finger lakes)5) many small hills (drumlins or moraines)5) many small hills (drumlins or moraines)6) parallel scratches on bedrock6) parallel scratches on bedrock

How does climate affect Landscape How does climate affect Landscape DevelopmentDevelopment

The rate at which landscape development occurs The rate at which landscape development occurs is dependent on temperature and moistureis dependent on temperature and moisture

In dry/arid climate – there is little vegetation so In dry/arid climate – there is little vegetation so sediments do not stay in place on steep slopes, so sediments do not stay in place on steep slopes, so they get rapidly carried away. This allows an arid they get rapidly carried away. This allows an arid climate to have steep slopes and sharp angular climate to have steep slopes and sharp angular features with sand dunes and sandblasted features with sand dunes and sandblasted bedrock.bedrock.

Ex: Southwestern USEx: Southwestern US In wet/humid climates – sediments will hold better In wet/humid climates – sediments will hold better

on steeper slopes, so the landscape is typically on steeper slopes, so the landscape is typically smoother and has more rounded features.smoother and has more rounded features.

Eastern USEastern US

Soil propertiesSoil properties

Looking at the soil’s permeability, Looking at the soil’s permeability, porosity, particle size, etc is important.porosity, particle size, etc is important.

The climate affects the soil that covers The climate affects the soil that covers the bedrockthe bedrock

1) Arid climates – thin soil coverings1) Arid climates – thin soil coverings

2) Humid climates – thick and full of 2) Humid climates – thick and full of organic soil coverings.organic soil coverings.

Drainage PatternsDrainage Patterns The drainage pattern (way in which water will The drainage pattern (way in which water will

flow) is mainly determined because of the flow) is mainly determined because of the resistance and structure of the underlying rock.resistance and structure of the underlying rock.

In horizontal layers, streams will develop a In horizontal layers, streams will develop a random patternrandom pattern

If there are structures like folding and faulting, If there are structures like folding and faulting, the rocks will control the directions of stream the rocks will control the directions of stream flow. flow.

Some bedrock structures are:Some bedrock structures are: Escarpments (cliffs) along the edge of Escarpments (cliffs) along the edge of

resistant layersresistant layers Ridges (narrow uplands) formed from Ridges (narrow uplands) formed from

resistant rocks in the Hudson-Mohawk resistant rocks in the Hudson-Mohawk Lowlands is SE New York.Lowlands is SE New York.