Rocks Weathering Erosion

•Rocks•Weathering•Erosion

SCIENCEREVISION

Igneous rocks are formed by the cooling of lava, and usually have bubbles.

Rock Types

Metamorphic rocks are rocks which have changed from one form to another. This normally occurs through extreme heat and pressure. They often have crystals.

Rock Types

Sedimentary rocks are made up of layers of sand, silt and clay that are pressed together over millions of years.

Rock Types

Sedimentary rocks are made up of many separate elements, therefore they are the most brittle rock type, resulting in them being more vunerable to weathering.

Weathering & Rocks

Weathering is caused by a number of different agents, such as: water, heat, cold, wind.

Powerful forces of nature are always at work. Rain pounds rocks, waves batter beaches, winds whip sand, acid and water mix to eats away at rocks, oxidisation (rusting) softens rocks, roots from trees work their way into cracks in rocks, extreme temperature changes crack rocks and gravity yanks rocks downward.

Weathering & Rocks

Fossils

Fossils are the remains or traces of an animal or a plant, which have been preserved in rock over millions of years. Fossils are found almost exclusively in sedimentary rocks and are revealed through weathering or erosion processes.

Dinosaur dies and is buried before its remains are destroyed.

Over time sediment builds up and press down on the buried remains.

Pressure, chemical reactions and time eventually turns the sediments into rock and the bones into mineralised fossils.

The fossils remain within the rock until uncovered through erosion or excavation.

Erosion

Erosion is the process by which materials are removed from the surface and transported to another location. The sediment which weathering leaves behind is carried away by gravity, water, wind and ice.

Erosion is caused by a number of different agents such as: water, gravity, wind and ice.

Erosion

Ice Erosion Gravity Erosion

Wind Erosion Water Erosion

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Erosion Investigation

3 Litres

Thinking about our erosion investigation we did with sand, what do you think would occur if 3 litres of water was poured onto castles, which were made from a harder soil, such as clay?

Erosion Investigation

Severe erosion is in an area near a fast-flowing creek. A fence next to the creek is in danger of falling down and there is a large area of soil that has been stripped away.

Erosion Investigation

•What could be the cause of the erosion?•What might happen if the erosion continues to develop?•What could be some ways to reduce or stop the erosion from getting worse?

The key principle in preventing or reducing erosion along creeks is to maintain good ground cover over the surface of the banks. This reduces contact between falling rain or floodwaters and the banks, decreasing the amount of soil eroded. The roots of vegetation growing along and on top of the bank also help to reinforce the soil and reduce the erosion rate, while vegetation growing within the creek channel or the placement of rocks can also slow water flow and trap sediment.

Erosion Solutions

Possible solution to reduce or stop erosion of river banks.

Erosion Solutions

Erosion Solutions

This river bank is at a reduced risk of erosion, due to the thick vegetation and ground cover surrounding it’s banks.