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Soil Formation, Mass

Movements and Wind Erosion

Soil has 4 components:

• Weathered rock

• Organic material (humus)

• Air

• Water

What is soil made of?

• Soil is formed from weathered rock and organic material (HUMUS)

• PARENT MATERIAL is what the soil forms from

• When the parent material is the underlying bedrock of the area the soil is called RESIDUAL SOIL (residual = what is left behind when the bedrock weathers)

• If the soil was formed in one place and carried elsewhere (by wind, water, glaciers, etc…) then the soil is called TRANSPORTED SOIL

• MUCH OF THE SOIL IN NYS IS TRANSPORTED SOIL LEFT BEHIND BY GLACIERS!

Cross section of soil layers

Each layer is called a

HORIZON

Horizon O/A = Topsoil

(mostly Humus, some

weathered rock)

Horizon B = Mostly

weathered rock, some

organic material (mineral

rich zone)

Horizon C = Broken

Bedrock

BEDROCK

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• IT TAKES 100-400 YEARS FOR 1cm OF TOPSOIL TO

FORM!!!!

• Plants hold the soil together and prevent soil

erosion

MASS MOVEMENTS

MOVEMENTS OF THE EARTH CAUSED

BY THE FORCE OF GRAVITY

CREEP

• Very slow downward movement of soil

– Only noticeable by the results of trees, fence posts, telephone poles, etc… that are tilted downhill

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LANDSLIDE

• RAPID mass movement of soil downhill (usually a very steep slope)

– AVALANCHE – landslide made of Ice & Snow as well as Soil

– SLUMP – small areas of land move downhill - especially along roadways that cut into the side of hills

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MUDFLOW

or LAHAR

• Very fast &

Dangerous

movement of

water

saturated soil

(MUD)

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Even though rapid mass movement

is more noticeable than slow mass

movement, overall, more material is

transported via creep than all others

combined

Wind Erosion

• Sediment – sand or smaller

• Arid regions or ocean coastlines

• 2 types:

1. Deflation – lowers the land

2. Sandblasting and Abrasion

Sandblasting and Abrasion

• Wind can only lift sand to about 1 meter

high - results in “Mushroom Rock”

• Frosted or Pitted sediments – rocks with flat

sides

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Windward side

Leeward side