The geology of Botswana plays a significant part in the country's economy. The basement rocks of the Kaapvaal-Zimbabwe craton extend into Botswana whilst in the east and southeast, metamorphic rocks of Archaean age are dominant. A younger cover of Karoo rocks and post-Cretaceous sediments conceal the western margins of these older rocks and largely conceal Proterozoic orogenic belts too. This younger stratum was laid down in the Kalahari Basin underlying large parts of the centre of the country. In the northwest of Botswana, more recent sediments overlie rocks of Meso- and Neoproterozoic age rocks, belonging probably to the Damara Belt.