The economy of the [[Dusts]] is predominantly concerned with providing sufficient food in spite of the difficulties presented by the arid [[climate]]. Crops are chosen mainly for their ability to be productive under such conditions. Industry is likewise geared toward satisfying the needs of intensive farming, including irrigation. Extractive industries focus on mining and quarrying. There are no substantial deposits of coal or mineral oil known in the Dusts. Trees are uncommon in the Dusts; baled scrub bushes and grasses or more recently [[trench-whale]] oil are used as sources of fuel. In past centuries, dead forests dating to the catastrophe were a more ready source of wood, but they have since almost all been harvested or succumbed to prolonged decay. Despite the isolation of many communities, trade is important to the survival of most of the inhabitants of the Dust, and if not to their survival, usually to their happiness. [[Professional]] services such as [[magic]] and [[medicine]] are based in larger settlements, although itinerant practitioners of most specialized trades and professions exist and serve the countryside irregularly. Tribes of lowland [[camel]] nomads often participate in trade with settled peoples, although such activities do not have a profound economic impact on upland [[pony]] and [[zebra]] civilizations. Besides barter, inhabitants use a variety of [[Currency|currencies]] for trade.