l1 Flashcards
The earth’s surface is composed of water and landmasses. The solid portion is made out of rocks and minerals that could experience changes either physically or chemically. The weathered materials are transported by different agents from one place to another and will settle down in a particular area. These progressions that happen are achieved by forms called exogenic processes. It includes weathering, erosion, and deposition.
Exogenic Processes
is the breakdown of rocks into pieces without any change in its composition. In this process, the size and shape of rocks changes and this occurs because of the following factors
Mechanical Weathering
due to tectonic forces, granite may rise to form mountain range. After the granite ascends and cools, the overlying rocks and sediments may erode. At the point when the pressure diminishes, the rock expands, cools, and became brittle and fractured.
pressure
rocks expand and are fractured when expose to high temperature. However, if the temperature drops to 0°C (freezing point of water), it also expands and causes fracture.
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Temperature
Generally, rocks have fracture in its surface and when water accumulates in the crack and at that point freezes, the ice expands and breaks the rock apart.
Frost Wedging
The breakdown of rocks is caused by impact and friction. This primarily occUrs during collision of rocks, sand, and silt due to current or waves along a stream or seashore causing sharp edges and corners to wear off and become rounded.
Abrasion
The roots grow causing penetration into the crack, expand, and in the long run, break the rock.
Organic Activity
Activities such as digging, quarrying, denuding forests and cultivating land contribute to physical weathering.
Human Activities
Animals like rats, rabbits and squirrels excavate into the ground to create a space for habitation.
Burrowing Animals
In xxx, there are changes in the composition of rocks due to the chemical reactions
CHEMICAL WEATHERING
It occurs in specific minerals which are dissolved in water. Examples of these minerals are Halite (NaCI) and Calcite (CaCO3). The formation of stalactites and stalagmites in caves are brought about by this chemical reaction.
Dissolution
Rock-forming minerals like amphibole, pyroxene, and feldspar react with water and form different kinds of clay minerals.
Hydrolysis
It is the response of oxygen with minerals. If the iron oxidizes, the mineral in rocks decomposes.
Rusting is an example of this chemical reaction.
Oxidation
IMPORTANCE OF WEATHERING
Weathering is an important process in the formation of soil. Soil is a mixture of grains, organic matter, H20, and gas.
is the separation and removal of weathered rocks due to different agents like water, wind, and glacier that causes transportation of the material to where they are deposited. Plants, animals, and humans play an important role in the erosional process.
EROISION
is the laying down of sediment carried by wind, flowing water, the sea or ice. Sediment can be transported as pebbles, sand and mud, or as salts dissolved in water.
Salts may later be deposited by organic activity (e.g. as sea shells) or
DEPOSITION
water picks up and moves particles of soil and rock. When the water slows down, for example by reaching flatter land, it starts to drop the particles it is holding. It drops the largest particles first and the smaller ones as it slows down even further.
WIND
in coastal environments, sediments are deposited along or near a coastline by low-energy waves that can no longer support their sediment load. Material carried by the sea is washed up by the water and begins to build up along the coastline, creating beaches and other coastal features such as spits and shoals.
SEA
Glaciers are not static objects; they move, albeit very slowly, flowing under their own weight, and they grow and shrink depending on the climatic conditions. As they move, they carve the landscape below them, picking up sediments and rocks of all sizes.
ICE
Exegonic process
The weathered materials place to another abd will settle down happeb are achieved by forms called exegonic process
exegonic process includes
weathering erosion deposition
Mechanical weathering
also known as physical weathering breaks down of rocks into pieces without any change in its composition it changes the size and shape of the rocks
Mechanical weathering occurs because of the following
Pressure temperature frost wedging abration organic activity human activities burrowing animals
