This photo is one of a nice set titled At the Ice Cave of Eben taken in March of 2007 (or view slideshow of the Eben Ice Caves). A document from a field trip led by Dr. John Anderton of the Northern Michigan University Department of Geography explains:
The Eben Ices Caves are located just a few miles north of the little town of Eben, within the Rock River Canyon Wilderness Area (RRCW). The RRCW, which became a Wilderness in 1987 as a part of the Michigan Wilderness Act, is located approximately 15 miles west of the town of Munising, MI, within the Munising Ranger District of the Hiawatha National Forest. It comprises 4,460 acres and contains outstanding natural features including Rock River, Silver Creek and Ginpole Lake. Within its interior there are two short user-developed trails (totaling about 1.75 miles) leading to Rock River Falls and the Eben Ice Caves. An estimated 1,700 people visit the area annually (USFS records) …
The Ice Caves are not true caves at all. They consist of walls or vertical sheets of ice that form across the face of overhanging rock outcrops. In the summer, small unimpressive waterfalls and groundwater seeps may found along the overhangs. In the winter, however, the water hits the cold air, drips downward under the influence of gravity and freezes, creating spectacular ice caves. Each winter they look a little different, but typically there are openings in the ice that allow you to walk behind the ice walls.
The rock overhangs, where the ice caves form, consist of outcrops of Munising Formation (Cambrian) with a capstone of AuTrain Formation (Ordovician). The outcrops are found along the south side of the valley of Silver Creek, which is part of a network of secondary glacial drainage channels that formed during the Marquette Advance (about 10,000 years ago). Theses secondary drainage channels flowed easterly into the AuTrain-Whitefish Channel, a primary glacial meltwater channel that flowed south to the Lake Michigan basin. Groundwater naturally seeps from these rocks, providing the water necessary to form the ice caves in the winter.
For directions and more info, check out Rock River Falls & Rock River Canyon Wilderness Area (Hunts’ UP Guide) and Visit The Eben Ice Caves (Marquette Country CVB).