170 likes | 214 Views
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
E N D
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
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.