so we are moving towards the westward, the kalahari.arrator: geographer brent mccusker is studying a rural area in the northern province to analyze the impacts of reform. is this true scrub land or is it more savanna? narrator: during apartheid this was a large, white-owned commercial farm. in 1995, 396 black south africans purchased the land as the mashambalogu communal property association-- or cpa. mccusker: in south africa after 1994, there were a series of social projects. one of the projects was to give a social benefits grant because people had been materially and economically dispossessed in apartheid. so at 1994, each citizen who was previously classified as historically disadvantaged was allowed to apply for a 15,000 rand social grant, which is about a little under $2,000. they could use it for a child's education. they could use it for building a house-- buying a new house. they could use it for upgrading their land, for fertilizers or they could purchase land with it. what we see on the mashambalogu cpa is a group of people

what we call the kalahari desert now was glaciated at that time. that wasn't long ago. that was only about 5% of geologic time. in the southwestern united states, too, there is evidence of a once widespread desert that existed 200 million years ago. fossil dunes are preserved in the upper wall of the grand canyon and in the sandstones of zion national park. the varied surfaces of the shifting sand dunes appear as crisscrossing sets of beds. their large size and coloration from the oxidation of iron show that they formed on dry land. since that time, plant and animal fossils indicate that this region became moist and forested. but in recent geologic time, conditions have become drier in response to plate motions, mountain building, and the development of rain shadows. some lands are deprived of moisture simply becausese they lie a great distance from the ocean, which is the primary source of moisture for rainfall. in western china, the gobi and the takla makan are both locked deep inside a land mass. moist air masses precipitate most of their water before reaching these