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Church, S.E., Nimick, D.A., Finger, S.E. and O’Neill, J.M. (2007) The Boulder River Watershed Study, Jefferson County, Montana. In: Nimick, D.A., Church, S.E. and Finger, S.E., Eds., Chapter B, Integrated Investigations of Environmental Effects of Historical Mining in the Basin and Boulder Mining Districts, Boulder River Watershed, Jefferson County, Montana, United States Geological Survey Professional Paper 1652-B, 697-740.

has been cited by the following article:

• TITLE: Analysis of Mountains Passes along the East-West Continental Divide and Other Drainage Divides Surrounding the Boulder River Drainage Basin, Jefferson County, Montana, USA

  AUTHORS: Eric Clausen

  KEYWORDS: Anastomosing Channel Complex, Clark Fork, Jefferson River, Missouri River, Silver Bow Creek

  JOURNAL NAME: Open Journal of Geology, Vol.7 No.11, November 23, 2017

  ABSTRACT: Detailed topographic maps of drainage divides surrounding the Jefferson County, Montana, Boulder River drainage basin were analyzed to determine the nature of drainage systems that preceded today’s Boulder River drainage system and how the Boulder River drainage system evolved from those earlier drainage systems. The Boulder River studied here drains in a north, east, and south direction to the Jefferson River, which at Three Forks, Montana joins the north-oriented Madison and Gallatin Rivers to form the north-oriented Missouri River. The North American east-west Continental Divide surrounds the Boulder River drainage basin western half and mountainous drainage divides with the Jefferson and Missouri Rivers surround the drainage basin’s eastern half. More than 25 deep mountain passes are notched into these drainage divides and provide evidence of the regional drainage system that preceded the present day Boulder River drainage system. Analysis of pass elevations and of orientations of valleys leading in opposite directions from those mountain passes shows that prior to Boulder River drainage system development immense volumes of south-oriented water moving in anastomosing complexes of diverging and converging channels flowed across the Boulder River drainage basin area and that the Boulder River drainage system evolved as deeper channels progressively captured flow from shallower channels. While not documented in detail crustal warping probably raised Boulder River drainage basin areas relative to adjacent valleys and basins as capture events took place. A water source was not determined, but may have been from a large North American continental ice sheet, although Boulder River drainage basin evolution probably occurred while mid Tertiary sediments were filling adjacent valleys and basins.