You searched for: Collection University of Michigan Herbarium Catalog Collection Remove constraint Collection: University of Michigan Herbarium Catalog Collection Institution University of Michigan. Libraries Remove constraint Institution: University of Michigan. Libraries Place Oakfield Twp., Flat Iron Lake, ca. 9 miles east of Rockford. Northeast margin of lake at Calvin College dock. Remove constraint Place: Oakfield Twp., Flat Iron Lake, ca. 9 miles east of Rockford. Northeast margin of lake at Calvin College dock.