Unveiling Landforms: Weathering, Erosion & Deposition Journey

Weathering/Erosion/Deposition All roads lead to… LANDFORMS!!

Let’s start with the foundation: • Various landscape features are the result of several processes: • Weathering • Erosion • Deposition • Tectonics • Glaciation • 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 Cycle • The sun and gravity control this cycle.

So, let’s start from the beginning. . . • In the beginning, there was . . . • Water • And 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!

Weathering • Weathering 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 = water • Lysis = Break • Hornblende 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 holes • Karst 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.

Unveiling Landforms: Weathering, Erosion & Deposition Journey