Hat Island is a small island on the eastern edge of the Beaver Island

Beaver Island (Lake Michigan)

Beaver Island is the largest island in Lake Michigan and part of the Beaver Island archipelago. Once home to a unique American monarchy, the island is now a popular tourist and vacation destination....

 archipelago in Lake Michigan

Lake Michigan

Lake Michigan is one of the five Great Lakes of North America and the only one located entirely within the United States. It is the second largest of the Great Lakes by volume and the third largest by surface area, after Lake Superior and Lake Huron...

. It is about 10 acres (0.04 km²) in size and located in eastern St. James Township

St. James Township, Michigan

St. James Township is a civil township of Charlevoix County in the U.S. state of Michigan. As of the 2000 census, the township population was 307.-History:...

, Charlevoix County, Michigan

Charlevoix County, Michigan

-Airports:*Beaver Island is served by two airlines:**Welke Airport**Beaver Island Airport-Ferry service:*Beaver Island Boat Company maintains a regular auto ferry from Charlevoix:*The Ironton Ferry at Ironton, Michigan crosses the south arm of Lake Charlevoix...

. It became part of the Michigan Islands National Wildlife Refuge

Michigan Islands National Wildlife Refuge

The Michigan Islands National Wildlife Refuge is a designation for eight Michigan islands in the North American Great Lakes. Owned by the United States federal government, they were set aside for ecosystem protection purposes by President Franklin D. Roosevelt 1943.Charity, Little Charity,...

 in 1943..

Like other islands in the Michigan Islands NWR, Hat Island was formed during the Wisconsin glaciation

Wisconsin glaciation

The last glacial period was the most recent glacial period within the current ice age occurring during the last years of the Pleistocene, from approximately 110,000 to 10,000 years ago....

 when a melting glacier randomly dumped a large quantity of boulder

Boulder

In geology, a boulder is a rock with grain size of usually no less than 256 mm diameter. While a boulder may be small enough to move or roll manually, others are extremely massive....

s and gravel

Gravel

Gravel is composed of unconsolidated rock fragments that have a general particle size range and include size classes from granule- to boulder-sized fragments. Gravel can be sub-categorized into granule and cobble...

 in a spot that became part of the lakebed. The island was selected for inclusion in the Michigan Islands NMWR because of its standing as a potential breeding ground for herring gull

Gull

Gulls are birds in the family Laridae. They are most closely related to the terns and only distantly related to auks, skimmers, and more distantly to the waders...

s and other fish-eating birds.

Hat Island is roughly four-sided, with an SSE-pointing forepeak that is said to look like the upturned brim of a hat.