| Abstract: | The geologic map of the Fraser quadrangle, Grand County, Colo., portrays the geology along the western boundary of the Front Range and the eastern part of the Fraser basin near the towns of Fraser and Winter Park. The oldest rocks in the quadrangle include gneiss, schist, and plutonic rocks of Paleoproterozoic age that are intruded by younger plutonic rocks of Mesoproterozoic age. These basement rocks are exposed along the southern, eastern, and northern margins of the quadrangle. Fluvial claystone, mudstone, and sandstone of the Upper Jurassic Morrison Formation, and fluvial sandstone and conglomeratic sandstone of the Lower Cretaceous Dakota Group, overlie Proterozoic rocks in a small area near the southwest corner of the quadrangle. Oligocene rhyolite tuff is preserved in deep paleovalleys cut into Proterozoic rocks near the southeast corner of the quadrangle. Generally, weakly consolidated siltstone and minor unconsolidated sediments of the upper Oligocene to upper Miocene Troublesome Formation are preserved in the post-Laramide Fraser basin. Massive bedding and abundant silt suggest that loess or loess-rich alluvium is a major component of the siltstone in the Troublesome Formation. A small unnamed fault about one kilometer northeast of the town of Winter Park has the youngest known displacement in the quadrangle, displacing beds of the Troublesome Formation.
Surficial deposits of Pleistocene and Holocene age are widespread in the Fraser quadrangle, particularly in major valleys and on slopes underlain by the Troublesome Formation. Deposits include glacial outwash and alluvium of non-glacial origin; mass-movement deposits transported by creep, debris flow, landsliding, and rockfall; pediment deposits; tills deposited during the Pinedale and Bull Lake glaciations; and sparse diamictons that may be pre-Bull Lake till or debris-flow deposits. Some of the oldest surficial deposits may be as old as Pliocene. |
| Genre: | USGS Numbered Series |
| ProdID: | 98800 |
| Citation Author: | Shroba, Ralph R.; Bryant, Bruce; Kellogg, Karl S.; Theobald, Paul K.; Brandt, Theodore R. |
| Citation Contributing Office: | Geology and Environmental Change Science Center |
| Citation Datum: | |
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| Citation Edition: | - |
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| Citation Language: | ENGLISH |
| Citation Larger Work Title: | |
| Citation LatN: | 0401500 |
| Citation LatS: | 0394500 |
| Citation LonE: | -1055200 |
| Citation LonW: | -1063000 |
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| Citation No Pagination: | N |
| Citation Number Of Pages: | |
| Citation Online Only Flag: | |
| Citation Phsyical Description: | Pamphelt: v, 26 p.; Map: 32 inches x 30 inches; Shaded Map: 32 inches x 30 inches |
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| Citation Public Comments: | |
| Citation Publisher: | U.S. Geological Survey |
| Citation Series: | Scientific Investigations Map |
| Citation Series Code: | SIM |
| Citation Series Number: | 3130 |
| Citation Search Results Text: | Geologic map of the Fraser 7.5-minute quadrangle, Grand County, Colorado; 2010; SIM; 3130; Shroba, Ralph R.; Bryant, Bruce; Kellogg, Karl S.; Theobald, Paul K.; Brandt, Theodore R. |
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| Citation Volume: | |
| Citation Year: | 2010 |
| Type: | citation/reference |
| Text: | Geologic map of the Fraser 7.5-minute quadrangle, Grand County, Colorado; 2010; SIM; 3130; Shroba, Ralph R.; Bryant, Bruce; Kellogg, Karl S.; Theobald, Paul K.; Brandt, Theodore R. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/sim_3130.jpg |
| URL (INDEX PAGE): | http://pubs.usgs.gov/sim/3130/ |
| Date Other: | Thu, 7 Oct 2010 00:00 -0500 |
| Publisher: | U.S. Geological Survey |
