Geography Mock Revision - Section A

 Rocks and Weathering - Plate Tectonics

Seafloor Spreading

Seafloor spreading is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge

Divergent Plate Boundary

When two oceanic plates diverge, the magma fills the remaining gap. An example of this is the Mid-Atlantic Ridge.

Collision Plate Boundary

When two continental plates of the same density collide, they cannot be destroyed therefore the only way is the up. An example for this is the Himalayas.

Subduction Place Boundary

Convection Currents move the plates. Usually, when oceanic and continental plates collide, the denser oceanic plate will subduct under the continental plate. An example of this is the ‘Ring of Fire’

Mountain Building

The geological processes, such as tectonic plate movement and volcanic activity, by which mountains are formed. Two examples include The Andes and the Himalayas.

The Himalayas were formed when the Continental Indian plate met the Continental Eurasian plate, and the two plates created fold mountains on impact, as they both buckled under each other's strength. 

The Andes were formed when the Oceanic Nazca plate was subducted under the Continental South American plate, causing the South American plate to fold into mountains under the pressure.

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Ocean Ridges

They are found along convergent plate boundaries, where one plate is submerged under the other, but underwater. When this happens, the continental plate gets squashed and forms a ridge.

Ocean Trenches

Ocean Trenches are formed when one plate is submerged under the other, but underwater. They are found along convergent plate boundaries. An example of this would be the Tonga Trench

Island Arcs

Island arc systems are formed when oceanic lithosphere is subducted beneath the oceanic lithosphere. They are consequently typical of the margins of shrinking oceans such as the Pacific, where the majority of island arcs are located.

Hydrology and Fluvial Geomorphology - Hydrological Cycle

The Hydrological Cycle vs the Drainage Basin

The Hydrological Cycle is the movement of water between the atmosphere, lithosphere, and biosphere. It has three major pathways: Precipitation, evaporation and vapour transport. Water precipitates from the sky, most of which fall into the oceans. It returns to the atmosphere by evaporation. Some flow from the land to the sea as runoff or groundwater water vapour is carried by atmospheric currents from the sea to the land. Net flow is measured in thousands of cubic kilometres per year.

The Drainage Basin is the Hydrological Cycle on a local scale, which is an area of land drained by a river and its tributaries, bounded by a watershed. It only has one input, precipitation, and two major outputs; evapotranspiration and runoff.

Hydrographs 

A hydrograph is a graph that shows changes in the discharge of a river over a period of time. There are two types of hydrographs, annual and storm.

An annual hydrograph records the river discharge of a specific river

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