MNphotoScenes
Maintain Formation
A portion of the St. Louis River flowing over rocks of the Thomson Formation.
The Thomson Formation consists of slate (23%-31%), siltstone (35%-43%) and graywacke (34%). (Percentages are from two measured sections and reported in 1970.) Most beds of the formation are less than one foot thick; and geologists believe the individual graywacke and siltstone beds represent individual sedimentary units.
The formation extends through northern Carlton and western St. Louis Counties, and westward as far as southeastern Otter Tail, northern Wadena and Southern Todd Counties. (Although these western locations are cut off by other formations.) the type location (where it was first identified) is along the St. Louis River at Thomson, Minnesota. The sediments formed in the Animikie Basin, which roughly follows western Lake Superior, although it extended west into central Minnesota. The Penokean Orogeny folded and metamorphosed the sediments about 1,700 million years ago.
Maintain Formation
A portion of the St. Louis River flowing over rocks of the Thomson Formation.
The Thomson Formation consists of slate (23%-31%), siltstone (35%-43%) and graywacke (34%). (Percentages are from two measured sections and reported in 1970.) Most beds of the formation are less than one foot thick; and geologists believe the individual graywacke and siltstone beds represent individual sedimentary units.
The formation extends through northern Carlton and western St. Louis Counties, and westward as far as southeastern Otter Tail, northern Wadena and Southern Todd Counties. (Although these western locations are cut off by other formations.) the type location (where it was first identified) is along the St. Louis River at Thomson, Minnesota. The sediments formed in the Animikie Basin, which roughly follows western Lake Superior, although it extended west into central Minnesota. The Penokean Orogeny folded and metamorphosed the sediments about 1,700 million years ago.