Stock Photo Description: ISS013-E-14843 (6 May 2006) --- Calcite Quarry, Michigan is featured in this image photographed by an Expedition 13 crewmember on the International Space Station. While the Great Lakes region of North America is well known for its importance to shipping between the United States, Canada, and the Atlantic Ocean, it is also the location of an impressive structure in the continent's bedrock--the Michigan Basin, NASA scientists point out. The Basin looks much like a large bull's-eye defined by the arrangement of exposed rock layers, which all tilt inwards towards the center forming a huge bowl-shaped structure. While this "bowl" is not readily apparent while on the ground, detailed mapping of the rock units on a regional scale revealed the structure to geologists. The outer layers of the Basin include thick deposits of carbonates (limestone and dolomite). These carbonate rocks are mined throughout the Great Lakes region using large open-pit mines. The largest carbonate mine in the world, Calcite Quarry, is depicted in this image. The mine has been active for over 85 years; the worked area (grey region in image center) measures approximately 7 kilometers long by 4 kilometers wide, and is crossed by several access roads (white) into various areas of the mine.