The Late Proterozoic Pocatello Formation; A record of continental rifting and glacial marine sedimentation, Portneuf Narrows, southeastern Idaho
Published:January 01, 1987
Paul Karl Link, 1987. "The Late Proterozoic Pocatello Formation; A record of continental rifting and glacial marine sedimentation, Portneuf Narrows, southeastern Idaho", Rocky Mountain Section of the Geological Society of America, Stanley S. Beus
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Portneuf Narrows is located on the Inkom, Idaho, 1:24,000 Topographic Quadrangle. The area is ideal for a one-day field trip because it is accessible from 1–15 (Exit 63-Portneuf Area) and is only 3 mi (4.8 km) from Pocatello where tourist services and the Idaho State University Library are available. Stops 1 and 3 are on paved roads. Stop 2 is on a dirt road that can be driven by passenger cars in dry weather. The entire area is on public land.
Stop 1 is an overview of Portneuf Narrows (Fig. 1A); it is reached by heading southeast from Pocatello on I–15 and taking exit 63S. Turn west (right) onto the frontage road (South Fifth Avenue), proceed 0.7 mi (1.1 km), cross under the freeway, and stop on the east side of the frontage road. If approaching from the south (Salt Lake City), take exit 63N, turn right at the frontage road, and proceed 0.2 mi (0.3 km) to Stop 1 on the left side of the road.
The outcrops south of Portneuf Narrows (Stop 2) are reached by heading south on Fort Hall Mine Road from exit 63. Cross the Union Pacific Railroad and the Portneuf River and proceed 0.2 mi (0.3 km) to Portneuf Road. Cross it, and continue straight for 0.6 mi (l km). There, bear left onto dirt road (avoiding road to sanitary landfill) and park at locked gate in Fort Hall Mine Canyon (Stop 2, Fig. 1A). The most complete stratigraphic sections can been seen in the base of the second canyon
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Rocky Mountain Section of the Geological Society of America
One of six volumes generated by each GSA section for the Decade of North American Geology (DNAG) project, this Centennial Field Guide contains descriptions of 100 sites or site clusters representing outstanding geologic locations in northern Arizona, Colorado, Idaho, Montana, North Dakota, New Mexico, South Dakota, Utah, Wyoming, and Alberta.