Parks_Content Page_Straight Lake Geology

Geology

Straight Lake State Park

About 1.1 billion years ago, the area that is now Straight Lake State Park was part of a mid-continental rift. Magma oozed out of the rift forming basalt, which can still be seen in several areas of the park. Many years later, during the last Ice Age, many of the park's features, as seen today, were formed. The most distinctive glacial feature in the park is the tunnel channel - formed when pressured water flowed under the glacier to cut the channel. This channel can be seen on the Ice Age Trail to the east of Rainbow Lake. Other glacial features in the park include a boulder valley, glacial erratics, eskers, kettles and hummocks.