The process of laying down materials, such as rocks

Erosion

Explanation:

Erosion is the geological process in which earthen materials are worn away and transported by natural forces such as wind or water. A similar process, weathering, breaks down or dissolves rock, but does not involve movement.

i assume that's what you mean by "laying down materials, such as rocks."

explanation:

with the profits from the european sales, merchants purchased europe's manufactured  goods, including tools and weapons. then the merchants shipped those manufactured  goods, along with the  american  sugar and rum, to west africa where they were bartered for  slaves.