Weathering/Erosion/Deposition

All roads lead to…

LANDFORMS!!

Let’s start with the foundation:Various landscape features are the result of

several processes:Weathering

ErosionDepositionTectonicsGlaciation

Glaciation is primarily responsible for the various Landscape regions of NYS.

But wait, there’s more . . .The driving force behind weathering,

erosion and deposition is…The WATER or HYDROLOGIC CycleThe sun and gravity control this cycle.

So, let’s start from the beginning. . .In the beginning, there was . . .

WaterAnd it was good.

The Water/Hydrologic Cycle

Evaporation Condensation Precipitation Infiltration Run-off

Without these processes, weathering, erosion and deposition could not occur.

So, now that we have a little background, let’s get started!

WeatheringWeathering is the breakdown of rocks.It occurs when rocks are exposed to

agents such as water and air.These weathering agents can change the

physical and chemical properties of rocks.

As rocks are broken down, they are classified as sediments

Sediments can be: boulders, cobbles, pebbles, sand, silt, clay and colloids

Remember this . . . ?

Types of weathering:

Physical/Mechanical:Rocks are broken down into smaller

pieces without changing the integrity or chemical composition of the rock.

Chemical:Rocks are broken down and the chemical

composition of the rock is changed.

Physical Weathering:

Frost action/Ice Wedging:

The breakup of rock as the result of the expansion and contraction of water.

Abrasion:The wearing down of rock as they rub and

bounce against each other.Common in stream beds, windy areas and

under glaciers.

Exfoliation:The peeling away of surface sheets of rock.Common with shale, slate and mica.

Chemical Weathering:

Oxidation: When oxygen reacts with minerals.

Remember ~ minerals are the building blocks of rocks and are composed of elements

i.e. When oxygen combines with Iron (Fe), it forms iron oxide, more commonly known as . . . Rust!

Hydrolysis: When water interacts with minerals.

Hydro = waterLysis = BreakHornblende and

feldspar often combine with water to form clay

Carbonation: When carbon dioxide interacts with minerals.

Causes the formation of:

Stalactites (top)Stalagmites (bottom)Sink holesKarst Topography

Weathering Rates:

The rate at which material is weathered is dependent upon:

Particle size/surface area(more surface area = more weathering)

Mineral Composition(softer minerals = more weathering)

Climate(warmer temperatures = more weathering)

A quick review . . .The water/hydrologic cycle is chiefly

responsible for weathering, erosion and deposition

Weathering is the breakdown of rock materials by either . . .

Physical means: frost wedging, abrasion, exfoliation or . . .

Chemical means: oxidation, hydrolysis and carbonation.

The rate of weathering depends on size, climate and mineral composition.