TITLE:
Origin of Little Missouri River - South Fork Grand River and nearby Drainage Divides in Harding County, South Dakota and Adjacent Eastern Montana, USA
AUTHORS:
Eric Clausen
KEYWORDS:
Boxelder Creek, Carter County (Montana), Deep Melt Water Erosion, Drainage Divide, Moreau River, Powder River
JOURNAL NAME:
Open Journal of Geology,
Vol.7 No.8,
August
7,
2017
ABSTRACT:
Barbed tributaries flowing in southeast directions, an asymmetric drainage divide
with both the South Fork Grand River and the North Fork Moreau River,
and the Jump-off escarpment-surrounded basin (interpreted here to be a large
abandoned headcut) are examples of topographic map evidence suggesting
the north oriented Little Missouri River valley eroded headward across a large
southeast oriented anastomosing complex of ice-marginal melt water flood
flow channels that once crossed Harding County, South Dakota. Additional
evidence includes southeast oriented tributaries to the northeast oriented
South Fork Grand River and multiple divide crossings (e.g. through valleys
and wind gaps) on the Boxelder Creek-Little Missouri River divide (in eastern
Montana and west of the Little Missouri River) and suggests deep regional
erosion occurred as the north oriented Little Missouri River valley eroded
headward into and across the region. Harding County is located south and
west of the southwest limit of coarse-grained glacial erratic material and ice-marginal
melt water flow routes logically should have crossed it. Deep melt
water erosion of Harding County and adjacent eastern Montana regions to the
west is not consistent with many previous drainage history and glacial history
interpretations, but is consistent with deep erosion by continental ice sheets.