Earth Science Exogenic Processes

Water Wind Glacial Ice Gravity

agents of erosion

exfoliation dome

an example of Sheeting/ exfoliation/ unloading is __

talus

during frost wedging the rocks that pile up at the bottom of the cliff into large lakes are called __

Carbonation Oxidation Hydrolysis Hydration Solution

examples of chemical weathering

Carbonation

mixing of water with carbon dioxide to make carbonic acid; Primarily occurs in wet and moist climates

solution

process by which the rocks are dissolved when exposed to rainwater; Usually happens in limestone and gypsum

biological weathering

weakening and subsequent disintegration of rock by plants, animals and people; Ex: mining; both chemical and physical weathering

abraision

Caused by rubbing and or bouncing of rocks with each other while they are transported by water, wind, glacial ice, or gravity

Hydration

Chemical combination of water molecules with a particular substance or mineral leading to a change in structure.

Hydrolysis

Chemical reaction between hydrogen ions and minerals

Chemical weathering

Decomposition, dissolution, alteration, of rock through chemical action

Weathering Erosion Mass waste Deposition

Earth's external processes

Mass wasting

Transfer of rock and soil downslope primarily by gravity

Erosion by water (fluvial)

Water erodes rocks and landscapes by transporting weathered materials from their source to another location where they are deposited

Salt crystal growth

Water with dissolved salt accumulates in these spaces and then evaporates and growing salt crystals wedge rocks apart; Occurs when salts crystallize out of the solution as water evaporates; Most common in dry climates like deserts

Frost Wedging

When water freezes it expands by about 9% and exerts tremendous force; This force breaks off rocks, tumble and pile up at the bottom of the cliff into large lakes

Erosion by wind (aeolian)

Wind erodes weathered rocks by picking them up and temporarily transporting them ; ex: sand dune

Physical / mechanical weathering Chemical weathering Biological Weathering

2 Types of Weathering

Thermal expansion or contraction/ block disintegration

Granular disintegration Differential thermal expansion and contraction if individual mineral grains in coarse crystalline rocks; Common in desert climates

Oxidation

Occurs when oxygen and water react with iron rich minerals which weakens the rock ex: rusting

Erosion by ice (glacial)

Particles are incorporated into the glacial ice through a process referred as picking

Weathering

Physical disintegration and chemical alteration of rocks at or near the earth's surface

Physical weathering

Physical disintegration and reduction in size of the rocks without changing in chemical composition

Erosion

Physical removal and transportation of weathered material by mobile agents such as water, wind or ice and gravity

Frost wedging Salt crystal growth Sheeting/ exfoliation/ unloading Thermal expansion or contraction/ block disintegration Abrasion

Physical/ mechanical weathering examples ()

Deposition

Process by which weathered and eroded materials are laid down or placed in a location that is different from their source

External / exogenic processes

Processes that occur at or near the earth's surface and powered by the energy from the sun

Internal / endogenic processes

Processes that occur underneath the earth's surface and are powered by the forces from within the Earth

External / exogenic processes

Produce changes to the landscape that influence surface and subsurface topography and landform development ; The processes lead to transformation of rocks

Sheeting/ exfoliation/ unloading

Reduced process in igneous rock causes it to expand in sheets; Because of pressure because of the uplift of rocks, the rock peel into sheets

Erosion by gravity

The downslope transportation if loosened, weathered materials and enables them to move without the aid of water, wind or ice; may be slow or abrupt; Unconsolidated materials stabilize near an angle of 35 degrees (angle of repose)

Water Oxygen Carbon dioxide

The most important agents/ catalysts of chemical weathering