Answer:
The answer to the question: Explain what causes this phenomenon, that of more sand dunes forming each year at the desert in Colorado, would be: the effects that both water and wind have over rocks to arode them, and break them into sand particles that are then deposited and carried by the wind. Water itself, forces sand grains from rocks to glue together, and the wind carries and also affects the form of sand dunes.
Explanation:
According to research, sand dunes are the result of the accumulation of sand grains in a specific location, either desert or beach, most commonly, at a much faster pace than they can be moved from the dune. There can also be an obstacle at the place where the dune forms, to stop sand from moving away. This sand is the product, usually, of the activities of water and wind on the surfaces of rocks, and the deposition of sand is thanks to wind itself. In the case of Colorado, given the vast amount of all these three elements: water, wind and rocks to form sand, as well as rocks that would serve as obstables, it is only justifiable that dunes would exist.