MODULE 5: WAETHERING, EROSION &DEPOSITION

HELLO MY DEAR STUDENTS.

Have you visited the islands in Caramoan or other islands in Bicol Region similar in land features? Caramoan is an internationally famous tourist destination in Camarines Sur. What is in this island that makes it attractive to tourists?

Rock formations and the white beach in Caramoan islands add wonder to the natural landscape. These features are due to a series of geologic processes occurring at the Earth’s surface known as the exogenic processes. These include weathering, erosion and deposition. These processes break rocks into smaller particles and transport them to lower locations through the action of natural agents like wind, water and ice. Together, they carve and change the shape of rocks, giving rise to interesting formations.

This module will allow you to explore more about exogenic processes and how they impact our landscape.

At the end of this module, you should be able to:

1. explain how weathering, erosion and deposition occur;

2. identify agents of weathering, erosion and deposition;

3. cite the results of weathering, erosion and deposition;

4. trace how rock materials are carried away through the action of natural agents;

5. appreciate the impact brought about by exogenic processes.

WEATHERING, EROSION AND DEPOSITION

Weathering

Weathering is a process by which rocks are broken into smaller fragments. This process is due to rocks’ exposure to varying temperature, pressure, substances and biological actions. Weathering can either be mechanical or chemical. Mechanical weathering happens when a large rock breaks into pieces physically without alteration in its chemical composition. For instance, the root of a plant growing in a crack of a boulder will eventually split the rock into smaller parts. In colder countries, water that gets into the pores of a rock may freeze and then thaw; alternate freezing and thawing splits rocks apart. In deserts, too much heat causes rock particles to expand and to contract when cooled; alternate expansion and contraction also results to breaking of rocks. When you kick a piece of rock and it crumbles down to pieces, you become an agent of mechanical weathering.

On the contrary, chemical weathering requires chemical reaction between rock minerals and other substances in the environment in order to break rocks. For example, the iron component of rocks may react with oxygen in water to form rust; rust makes the rocks weak and brittle causing them to disintegrate. Limestone, a carbonate-containing rock, may decompose when carbon dioxide comes in contact with it. Carbon dioxide is absorbed by rainwater and brought to the ground. As groundwater enters pores and cracks in limestone, the rock dissolves. Gradually, an opening is created forming a cave. Sometimes, water dissolves some minerals in rocks like calcite and halite, causing their molecules to dissociate into ions and to be carried away by water. This makes the rock weak and brittle.

Mechanical and chemical weathering work together to produce fine, loose rock particles called sediments. Sand, silt and clay are terms used to describe the size of sediment. Gradually, sediments turn into soil, a highly valuable resource. Soil is composed of weathered rock particles, organic matter, mineral fragments, water and air.

Erosion

Weathering makes rocks smaller and lighter, thus easier to be moved and transported. When rock particles are moved from one place to another, the process is called erosion. As agents of erosion carry the rock particles, they lose energy until such point that they can no longer hold them. Rock sediments are then dropped to certain locations, usually of lower elevation. Deposition is the process by which sediments are dropped off by agents of erosion.

Agents of Erosion

WATER

Rainwater that does not soak or evaporate runs over the ground, carrying with it rock particles. This surface runoff eventually enters a body of water such as streams, lakes and oceans. As water continues to move along, it picks up sediments. Lightweight sediments become suspended in water and are carried away by water while heavier particles roll along the bottom. Large ocean waves pound along edges of land, wearing down rocks in it. Sediments deposited in ocean basins may gradually undergo lithification to form sedimentary rocks.

WIND

Loose rock and soil particles are carried away by wind and are deposited at other places. Wind is capable of transporting light particles over large areas thousands of kilometers away. When wind blows strongly, it may pick larger particles causing sand storm in deserts and arid regions. A dust storm may take place when fast wind lifts dry and fine soil particles.

GLACIERS

Glacier is a large mass of ice and snow that forms in colder parts of the world. As glaciers move across land, they erode solid rocks and deposit eroded materials somewhere. When ice at the base of a glacier melts, water penetrates the pores and cracks of the rock beneath it. As water refreezes, rock fragments are plucked by the ice and are dragged along to different locations. Glacial erosion scars rock surface forming grooves and striations.

GRAVITY

Gravity is a major force that drives erosion and deposition. Soil and weathered materials in high elevations like hills and mountain are pulled down by gravity. Loose rocks on a steep slope may roll downside and deposit materials at the base. The downslope movement of large amounts of soil and rock particles due the effect of gravity is called mass wasting or mass movement. Mass wasting can be slow or fast. Slow mass wasting occurs gradually. Creep is the slow movement of particles from higher to lower elevations. It happens very slowly that it is almost unnoticeable, yet it is the most widespread affecting nearly all slopes with weathered rocks at the surface.

Depostion

Deposition

Deposition of sediments is the geological process where materials carried by wind, water, ice, or gravity are dropped and accumulate in a new location. This laying down of sediment can result in the formation of sedimentary rocks and influence various environments like coastal areas, riverbeds, and lake bottoms.

LETS UNDERSTAND FURTHER WEATHERING, EROSION AND DEPOSTION BY WATCHING THIS EXPERIMENT

To test if you understand our lesson today, try to assess this link. Do not forget to save a screeshot of your work.

WORDWALL: Weathering, Erosion, deposition

https://wordwall.net/resource/30133263/weathering-erosion-deposition

Weathering, erosion, and deposition can create beautiful and dramatic scenery. Through processes like wind and water action, erosion shapes landscapes over time, forming unique and visually stunning features like canyons, arches, and towering rock formation.

Here are some of the examples:

Canyons and Valleys:
Rivers carve deep canyons, while glaciers create U-shaped valleys, both showcasing dramatic slopes and rugged terrain.
Arches and Hoodoos:
Wind and water erosion can sculpt rock formations into intricate arches and unique hoodoos, as seen in places like Utah's Arches National Park.
Coastal Formations:
Coastal erosion can create sea stacks, arches, and cliffs, adding to the beauty of coastlines.
Desert Sculptures:
Wind erosion in arid regions can sculpt rock formations into fantastic shapes, like the ventifacts found in deserts.
Mountain Landscapes:
While mountains are formed by geological uplift, erosion plays a crucial role in sculpting their peaks, ridges, and valleys, making them visually appealing.

HELLO STUDENTS I KNOW THAT YOU HAVE BEEN DOING YOUR BEST TO LEARN BUT REMEMBER TO TAKE CARE OF YOURSELF ALSO. MANAGE YOUR TIME AND WORK. YOUR MENTAL HEALTH IS IMPORTANT. HAPPY LEARNING.

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