geography

Weathering :The rock is broken down and is weakened but does not move.

Erosion :When rock is worn away and moved by forces of nature.

types of weathering: Mechanical, Chemical, Freeze thaw, Biological, Onion-skin, Physical.

Chemical weathering :It’s when acids in rain and sea/river water react with rock and cause it to wear away.

freeze thaw weathering: water fills a crack in a rock,the water freeezes and expands, the rock breackes into little pices.

Abrasion – River uses rocks and stones to wear away the banks and beds.

Solution – Some rock dissolves in the water

Attrition – Rocks and stones rub and knock against each other and they become smooth and rounded.

Hydraulic action – River  forces air into cracks in the bed and banks; the bed expands and the bank crumbles.

Drainage Basin -A drainage basin is the area of land around the river that is drained by the river and its tributaries.

Landforms-Landform is a shape or characteristic of the land caused by either erosion process or depositional process.

Gorge-A gorge is a sloped, narrow, steep sided valley that is usually found immediately downstream of a waterfall. It is formed by the gradual retreat of waterfalls over hundreds, sometimes thousands of years.

Waterfall-Waterfalls are found in the upper course, where the layer of hard rock sits on top of a layer of soft rock. As the water hits the bottom of the waterfall, it erodes the soft rock through hydraulic action and abrasion, creating a plunge pool. Over time the plunge pool gets bigger until the hard rock overhangs. Eventually the hard rock will collapse and the waterfall will retreat upstream, leaving a steep sided gorge.

Meanders-They are found in the middle course, usually in lowland and flatter areas. The dominant form of erosion here is lateral erosion. Due to constant erosion and deposition, meanders are always changing shape. The flat area of land on either side of the meanders is called a floodplain.

Oxbow Lakes-Oxbow lakes are found in the middle course. They form when a meander is cut off from the main channel. This happens because the meander neck is eroded away.

Oxbow Lake Formation-the rock of the meander in gradually eroded, water takes the fast root, Deposition seals off the meander. The meander neck is eroded completely. Meander is cut off forming an oxbow lake. 

Headlands and Bays-Differential erosion: Different rates of erosion. The coast is made up of bands of different types of rock. Some rock types such as granite are hard rock and are resistant to erosion.  Headlands and bays are created by perpendicular layers of hard and soft rocks to the sea. When they are parallel they erode at the same time. 

Caves – Waves erode cracks in the headland. The crack widens due to processes like hydraulic action. Erosion continues to create a cave.

Arches – The waves continue to erode the cave until eventually the caves erode right through the headland to form an arch.

Stacks – The arch erodes more due to weathering processes like biological weathering, the top of the arch becomes unsupported.  It collapses into the sea leaving a stack.

Stumps – Erosion continues to attack the stack at the bottom until it collapses. A stump is formed when the stack collapses.

Glacier-A slow moving mass or river of ice formed by the accumulation and compaction of snow on mountains or near the poles.

Snow collects in a natural hollow on the side of a mountain.

 The hollow is deepened and widened by the corrie glacier through the process of abrasion and plucking.

The over-depping leads to an ‘armchair’ shape characteristic of a corrie and causes a ‘rock lip’ to be formed.

Eventually the glacier and ice might melt and a lake can form in the corrie. This is called a tarn.

Aretes-Erosional glacial landform. They are often between two corries and around a pyramid peak.

Pyramid Peaks-Erosional glacial landform, formed when three or more corries cut into the same mountain. This creates a steep sided mountain with a very sharp, often point-like shape.

The ice mass (glacier) flows. As it does this it erodes the ground below. Examples of this are plucking and abrasion. Glaciers are found in very cold regions where lots of freeze thaw weathering

Erratics-An erratic is a boulder that is different to a bedrock upon which it is sitting. They have been transported or deposited by a glacier. Therefore erratics are useful indicators of the direction the glacier travelled in.

Drumlins are formed of till. They are elongated features that can reach a km or more in length, 500m or so in width and up to 50m in height.

It is common to find several drumlins grouped together. A collection of drumlins is called a swarm.

Moraine-A type of landform that is created when a glacier deposits the material (till) that it has been transporting. It does this by melting or dragging along and dropping rocks at the side of the glacier. It is made up of unsorted angular rocks.

types:

Lateral

Medial

Ground

Recessional

Terminal