8255

• UCREFRP Catalog Number: 8255
• Author: Grams, P. E. and J. C. Schmidt.
• Title: Geomorphology of the Green River in the Eastern Uinta Mountains, Colorado and Utah.
• USFW Year: n.d.
• USFW - Doc Type: Logan, Utah.
• Copyright Material: NO

Grams and Schmidt

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trending Lodore Canyon are aligned with these geologic structures. The largest tributaries
. such as Pot Creek, Zenobia Creek, and Jack Springs Draw run adjacent to mapped faults.
The Green River in the eastern Uinta Mountains is divided into six sub-reaches
based on the distinction between canyon-bound and open or 'park' reaches and were
originally named by Powell (1875). These reaches have distinct meander patterns and
relationships with geologic structures.
The river planfonn in the canyon reaches of Lodore Canyon, Whirlpool Canyon,
and Split Mountain Canyon does not meander; the river tends to flow straight for about 2
to 4 Ian then bends abruptly into another straight reach. Many of these bends, like
tributary alignments, are coincident with geologic structures. In Split Mountain Canyon,
for example (Fig. 1), the river cuts across the rock strata into the core of the anticline then
turns 90 degrees west and flows along the structural axis for about 6.5 Ian, and then, just
as abruptly, veers back across the structural trend and flows out of the anticline into the
Uinta Basin. These reaches all contain debris fans and may be called debris-fan
dominated canyons in the terminology of Schmidt and Rubin (1995).
Meandering reaches fall into two categories, restricted meanders and incised
meanders. In the single bend through Echo Park, the channel and the valley have the same
meander amplitude, characteristic of incised meanders. In the restricted meanders of
Brown's Park and Island Park, the Green River flows through soft Tertiary and Mesozoic
sediments in occasional contact with more resistant Paleozoic bedrock on the outsides of
meander bends. The meander amplitude of the channel is less than that of the valley and
only the outside margins of the meanders impinge on bedrock.
4. HYDROLOGICAL SETTING
The study reach consists of two hydrologically distinct reaches, demarcated by the
Yampa River confluence at Echo Park. Flow is completely regulated by Flaming Gorge
Dam for a distance of about 104 Ian upstream from Echo Park (Fig. 1). A gaging station
near Greendale, Utah, immedi~tely below the dam, measures flow for this reach; the