Dryland Landscapes: OCR A-Level Geography

It may surprise you to learn that there are cold deserts. Drylands are places that receive little rainfall. They are arid. They are semi-arid. They are sub-humid. Deserts appear everywhere from Greenland to Australia.

Geographers have began to think of deserts as a system. A system is a series of processes that interrelate and interact with one-another. A change in one process can go on to effect the entire system.

There are a number of factors that commonly affect dryland systems. Position - ie latitude - is a major factor, determining sunlight levels during the year. Geology and climate are among the other variables.

Weathering in deserts can produce very different results. One rock type will react differently from another. Likewise, the presence of moisture or salt will alter the outcome. Hydrolysis is a form of chemical weathering.

Deserts are alive with change. No two are the same. The deserts of Egypt, for instance, look nothing like the deserts of Arizona. Aeolian and other forces create different landscape over great periods of time.

Deserts may be dry, but that does not means they do not contain water. The Nile, for example, is a river that runs through Egypt. The Nile is an example of exogenous drainage. Endorheic drainage is is similar, but flows inland.

Over long periods of time, climates have changed. In the bedrock of many deserts on Earth, fossils are found that indicate the presence of sea-life at a point in the past. Pluval periods are times of rainfall in the desert.

Desertification is the process where land that was once fertile becomes desert. UNESCO warns that one third of the Earth's surface on land is threatened by desertification. This process is accelerated by human intervention.

Answer these ten questions to help you revise what we have covered in this course. Questions are based on the modules we have presented and cover dryland landscapes and desertification.