Kalkaska sand is the official soil of the U.S. state of Michigan.
The distinctive sand layers can range from black to yellowish-brown and are commonly 2 to 4 feet (0.6 to 1.2 m) deep.
This makes it a valuable asset in forestry and certain types of agriculture.
It is also largely responsible for the remarkable water quality of lakes and rivers located in areas of the state where these soils are abundant.
Unique to the state, Kalkaska Sand covers nearly 1 million acres (4,000 km2) in 29 Upper and Lower Peninsula counties.