Final answer:
Large circular downwarped structures are called basins. They form when the Earth's crust is subjected to tectonic forces that cause the crust to sag or sink. Basin formation is associated with the accumulation of sediments and the formation of valuable resources.
Step-by-step explanation:
Large circular downwarped structures are called basins. These basins form when the Earth's crust is subjected to tectonic forces that cause the crust to sag or sink. The process of basin formation is usually associated with the accumulation of sediments in the depressed area, which can result in the formation of valuable resources such as oil and gas deposits. Basins are the opposite of domes, which are large circular upwarped structures.