Desert similar. They occur in regions where large temperature differences occur between sea and land. Moist warm air rises over the land, deposits its water content and circulates back to sea. Further inland, areas receive very little precipitation. The Thar Desert near the India/Pakistan border is of this type. In some parts of the world, deserts are created by a rain shadow effect. Orographic lift occurs as air masses rise to pass over high ground. In the process they cool and lose much of their moisture by precipitation on the windward slope of the mountain range. When they descend on the
Thar coalfield metres and rests upon a structural platform in the eastern part of the desert. The generalised stratigraphic sequence in the Thar coalfield area is shown in table. It comprises Basement Complex, coal bearing Bara Formation, alluvial deposits and dune sand. The coal beds of variable thickness ranging from 0.20–22.81 metres are developed. The maximum number of coal seams found in some of the drill holes is 20. The cumulative thickness of the coal beds range from 0.2 to 36 metres. Claystone invariably forms the roof and the floor rock of the coal beds. The coal is brownish black, black and