Why are the interior plains so rich in natural resources?

The interior plains are rich in Natural Resources due to their extensive sedimentary deposits, which were formed from ancient seas and rivers that once covered the region. This geological history has resulted in significant reserves of fossil fuels, such as coal, oil, and natural gas, as well as fertile soils conducive to agriculture. Additionally, the area's diverse ecosystems support various minerals and freshwater resources, making it a vital region for resource extraction and agricultural production.