MNA’s 100th acquisition, Twin Waterfalls Memorial Plant Preserve, was acquired in 1986 after funds were raised to honor Rudy Olson, an MNA member and avid bird watcher from Calumet who served on the Detroit Audubon Society’s Board of Directors for more than 18 years. Two additional parcels were later purchased and added to the preserve, which now totals 15.45 acres.
The sanctuary is home to a variety of plants such as the giant twisted stalk, which is a member of the lily family, and American milletgrass, a five-foot tall woodland grass distinguished by a foot-long panicle. In the large horizontal crevices along the sandstone cliffs, the slender cliff brake fern grows. This small fern is only found in six counties in the Upper Peninsula and in Alpena County in the Lower Peninsula, and it grows on moist, alkaline rocks where seepage through the rocks supplies constant moisture.
A grove of American beech trees grow at Twin Waterfalls Plant Preserve near the northern reach of their range in the Upper Peninsula. Beech drops, a tan-colored parasitic plant, are often overlooked on the trail. They grow 6-18 inches tall and anchor themselves to the roots of beech trees.
Despite its smaller size, Twin Waterfalls Plant Preserve captures both beautiful scenery and recognizes the contributions of many important MNA members.
The Munising Formation
The vertical walls of both waterfall canyons are part of the Munising Formation, which consists of ancient sandstone about 550 million years old. The buff, rose-colored sandstone is soft rock easily eroded by ice and water due to its composition of small quartz particles that resemble beach sand. The upper rock capping the Munising Formation is made of harder dolomite sandstone, known as the Au Train Formation. This cap erodes at a slower rate than the surrounding rock, which results in the shelf over which the water drops.
Both waterfalls at Twin Waterfalls Plant Preserve are dedicated to the many friends of MNA and the thoughtfulness of the donors who made the sanctuary possible. Also known as Tannery Falls, MNA has renamed and refers to this as Olson Falls, in honor of member Rudy Olson. Memorial Falls is named to honor more than a hundred past MNA members who had contributed to the association by the time of acquisition.