Weathering and Erosion Flashcards

Flashcards for weathering and erosion lecture

Weathering

Weathering refers to the break down of rocks into smaller pieces when the solid earth is exposed to the elements of weather it changes, breaks down and results in new landforms forming.

Igneous Rocks

Rocks formed when molten rock (magma/lava) material cools and hardens. Characteristics: Hard, contain crystals, and contain no fossils

Sedimentary Rocks

Rocks formed from fragments of other rocks that have been compressed and hardened in layers (strata). Characteristics: Form layers, soft, contain fossils.

Metamorphic Rocks

Rocks that have developed from igneous or sedimentary rocks that have been changed by heat or pressure. Characteristics: Crystalline, soft to hard, thinly layered.

Intrusive/Plutonic Rocks

Igneous rocks that form from magma.

Extrusive/Volcanic Rocks

Igneous rocks that form from lava.

Factors Affecting Weathering Rate

Climate (temperature differences), Rock Type (mineral composition), Rock Structure (cracks, porosity), Vegetation (root expansion), Relief, Hot and Wet Conditions (chemical weathering), People (pollution, deforestation).

Mechanical/Physical Weathering

The breakdown of rocks through physical forces like exfoliation and freeze-thaw cycles.

Freeze Thaw Weathering

Occurs when water leaks into the cracks of rocks, it freezes and causes the rock to crack. Repeated expansion eventually breaks rocks apart.

Exfoliation

When a rock is heated, it expands; at night, temperatures decrease, and the rock contracts. The repeated expansion and contraction will break the rock in layers.

Chemical Weathering

The interaction of rock with mineral solutions (chemicals) to change the composition of rocks through processes like hydrolysis, oxidation, solution, and carbonation.

Solution (Chemical Weathering)

Rocks react with acids in water and dissolve, often indicated by small holes in coastal rocks.

Oxidation

Occurs when iron-containing rocks are exposed to oxygen, forming iron oxide (rust) and causing the rock to break into smaller pieces. Fe + O2 → Fe2O3

Hydrolysis

When rocks sit in water for extended periods, they begin to break down and have a clay-like texture.

Carbonation (Acid Rain)

Water absorbs carbon dioxide, forming carbonic acid that reacts with many common minerals.

Acid Rain Formation

The burning of fossil fuels releases sulfur, carbon, and nitrogen into the atmosphere, which combine with moisture to form sulfuric acid, carbonic acid, and nitric acid.

Biological Weathering

Occurs when burrowing animals, humans, or plants interfere and work their way into rocks. Some plants and animals can produce weak acids that chemically weather the rock.