srp_srfgeo surficial geology units, polygons srp_srfcont surficial geology contacts, lines srp_pingos pingos, points srp_terraces terrace risers, lines
Reger, R.D., Burns, P.A.C., and Staft, L.A., 200812, Surficial-geologic map of the Salcha River-Pogo area, Big Delta Quadrangle, Alaska: Report of Investigations RI 2004-1C, Alaska Division of Geological & Geophysical Surveys, Fairbanks, AK.Online Links:
This is a Vector data set.
Planar coordinates are encoded using coordinate pair
Abscissae (x-coordinates) are specified to the nearest 0.001
Ordinates (y-coordinates) are specified to the nearest 0.001
Planar coordinates are specified in meters
The horizontal datum used is North American Datum of 1927.
The ellipsoid used is Clarke 1866.
The semi-major axis of the ellipsoid used is 6378137.
The flattening of the ellipsoid used is 1/298.25722210088.
| Value | Definition |
|---|---|
| Qt1 | Stream-terrace alluvium |
| Qt2 | Stream-terrace alluvium |
| Qgd | Undifferentiated glacial drift |
| Qa | Floodplain alluvium |
| Qt | Stream-terrace alluviumAlaska Division of Geological & Geophysical Surveys |
| Qc | Undifferentiated colluvium |
| Qcd | Debris-flow deposit |
| Qcl | Landslide deposit |
| Qca | Mixed colluvium and alluvium |
| Qer | Retransported loess |
| b' | Thinly covered bedrock |
| b | Undifferentiated bedrock |
| Value | Definition |
|---|---|
| Exposed bedrock | Exposed bedrock |
| Undifferentiated colluvium | Undifferentiated colluvium |
| Thinly covered bedrock | Thinly covered bedrock |
| Stream-terrace deposits? | Possible stream-terrace deposits |
| Stream-terrace alluvium | Stream-terrace alluvium |
| Retransported loess | Retransported loess |
| Mixed colluvium and alluvium | Mixed colluvium and alluvium |
| Landslide deposits | Landslide deposits |
| Glacial deposits | Glacial deposits |
| Floodplain alluvium | Floodplain alluvium |
| Debris-flow deposit | Debris-flow deposit |
| ? Landslide deposit | Possible landslide deposit |
| ? Exposed bedrock | Possible exposed bedrock |
| Stream-terrace deposits | Stream-terrace deposits |
| Value | Definition |
|---|---|
| b | Undifferentiated bedrock |
| b' | Thinly covered bedrock |
| Qc | Undifferentiated colluvium |
| Qca | Mixed colluvium and alluvium |
| Qcl | Landslide deposit |
| Qer | Retransported loess |
| Qgd | Undifferentiated glacial drift |
| Qt | Stream-terrace alluviumAlaska Division of Geological & Geophysical Surveys |
| Qcd | Debris-flow deposit |
| Qa | Floodplain alluvium |
To show the distribution of unconsolidated deposits and undifferentiated bedrock units in the Salcha River-Pogo area.
Bacon, C.R., and Lanphere, M.A., 1996, Late Cretaceous age of the Middle Fork Caldera, Eagle Quadrangle, east-central Alaska: U.S. Geological Survey Bulletin B 2152.
Moore, T.E., and Dumoulin, J.A., 1996, Geologic Studies in Alaska by the U.S. Geological Survey. 1994: U.S. Geological Survey Bulletin B 2152.
Pewe, T.L., Burbank, L., and Mayo, L.R., 1967, Multiple glaciations in the Yukon-Tanana Upland, Alaska: U.S. Geological survey Miscellaneous Investigations Map I 507.
Weber, F.R., 1983, Glacial geology of the Yukon-Tanana Upland - a progress report: University of Alaska Museum Occasional Paper No. 2.
Thorson, R.M., and Hamilton, T.D., 1983, Glaciation in Alaska: Extended abstracts from a workshop: University fo Alaska Museum Occasional Paper No. 2.
Weber, F.R., 1986, Glacial geology of the Yukon-Tanana Upland: Alaska Geologicl Society, Anchorage, Alaska.
Hamilton, T.D., Reed, K.M., and Thorson, R.M., 1986, Glaciation in Alaska: The geologic record: Alaska Geological Society, Anchorage, Alaska.
Data sources used in this process:
Data sources used in this process:
Werdon, M.B., Newberry, R.J., Athey, J.E., and Szumigala, D.J., 2004, Bedrock geologic map of the Salcha River-Pogo area, Big Delta Quadrangle, Alaska: Report of Investigations RI 2004-1B.
Initial reconnaissance field observations were made in 2001 and 2002, after which surficial geology air-photo interpretations were done. Contacts were hand-drawn, using a magnifying stereoscope, onto acetate air-photo overlays at the scale of the air-photos (approximately inch-to-the-mile). The air-photos were taken in July 1978, July 1979, and August 1981. During summer field work in 2001 and 2002, map units were described, samples collected for analysis, and a limited number of test pits was dug. The accuracy of the map unit boundary locations vary due to the scale and interpretive nature of the mapping, but are expected to be accurate to at least 20 m. Information from previous geologic reports was incorporated during the interpretation process.
The surficial geology was first hand-drawn, using a magnifying stereoscope, onto acetate overlays registered to 1:50,000-scale (nominal) prints of digital aerial photographs. The horizontal accuracy of the map unit boundary locations varies due to the scale and interpretive nature of the mapping, but is expected to be accurate to at least 15 m. Geologic contacts on the acetate overlays were transferred to paper USGS topographic maps using a zoom transfer scope. The paper maps were scanned and georeferenced, and map unit boundaries were digitized on-screen into ArcGIS at a zoomed-in scale of approximately 1:25,000. Total horizontal accuracy of the mapped surficial-geologic contacts is believed to be on the order of 25 m or better, with somewhat lesser accuracy expected in areas of rugged relief.
This dataset includes shapefiles that contain information about the mapped and interpreted surficial-geologic deposits in the map area. Subsurface data were not available for use in creating these shapefiles, other than scattered soil pits dug to depths no more than about 1 m and observations of exposures in river banks. Soil colors were described using the Munsell soil color charts. The Wentworth scale was used for grain size classification.
Polygon topology is present for polygon shapefiles.
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Report of Investigations 2004-1C
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| Data format: | ArcGIS Shapefile (version ESRI ArcGIS 9.x) |
|---|---|
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