The last glacier in Minnesota heaped up coarse materials in front of it as it advanced across the state like a giant bulldozer. When it retreated, it left behind a band of these coarser materials diagonally across the state from northwest to southeast that is typified by rolling hardwood forested hills. Elk River is situated in this band of coarser materials, which is the reason why gravel mining is so prevalent within the city and much of the area is not considered good crop land. The finer materials deposited to the south of the coarse materials, called an outwash plain, is typified by prairie habitat.
Elk River is located on the edge, between the woods and the prairie.
This natural boundary between prairie and woods was also the boundary between Indian nations. As the Dakota retreated southward from the advancing Ojibwe nation, clashes occurred. Two battles between these enemies took place where the Elk River meets the Mississippi in 1772 and 1773. Both tribes ceded the area of land that includes present day Sherburne County to the United States in 1837. Whites called it the St. Francis River.