Lake Agassiz Peatlands Natural Area in northern Minnesota protects 25,411 acres of peatland in Koochiching County on part of the former bed of glacial Lake Agassiz. Recognized as a National Natural Landmark in 1965, it is valued as an outstanding example of the nation’s natural history and for showing about 11,000 years of peat accumulation. Its importance rests on the scale and quality of its peatland features, including Myrtle Lake Bog, which developed unlike the usual pattern of lakes gradually filling in. The area is also regarded as an excellent example of raised bogs and string bogs, with the Myrtle Lake Peatland Scientific and Natural Area encompassing 22,950 acres.