The engineering-geologic map is derived electronically, using Geographic Information System (GIS) software, from the surficial-geologic map of the second segment of the proposed natural gas pipeline corridor through the upper Tanana valley, a 12-mi-wide (19.3-km-wide) area that straddles the Alaska Highway through the upper Tanana River valley from the Robertson River eastward to near Tetlin Junction in the Tanacross Quadrangle (Reger and Hubbard, PIR 2009-6A). Surficial-geologic units were initially identified by interpretation of false-color ~1:65,000-scale infrared aerial photographs taken in July 1978, August 1980, and August 1981 and locally verified by field checking in 2007 and 2008. The map shows the distribution of surficial-geologic and bedrock units grouped genetically with common properties that are typically significant for engineering applications.

During 2009, the Alaska Division of Geological & Geophysical Surveys continued a program, begun in 2006, of reconnaissance mapping of surficial geology in the proposed natural-gas pipeline corridor through the upper Tanana River valley. The study area is a 12-mi-wide (19.3-km-wide) area that straddles the Alaska Highway from the western boundaries of the Tanacross B-3 and A-3 quadrangles near Tetlin Junction eastward to the eastern boundaries of the Nabesna D-1 and C-1 quadrangles along the Canada border. Mapping during 2008-2009 in the Tanacross and Nabesna quadrangles linked with the mapping completed in the Tanacross, Big Delta and Mt. Hayes quadrangles in 2006-2008. Surficial geology was initially mapped in this third corridor segment by interpreting ~1:65,000-scale, false-color, infrared aerial photographs taken in July 1978 and August 1981 and plotting unit boundaries on acetate overlays. Verification of photo mapping was accomplished during the 2008 and 2009 summer field seasons, when map units were described, soil pits were hand dug, and samples were collected for analyses.

The engineering-geologic map, on two sheets, is derived electronically from the surficial-geologic map of the initial segment of the proposed natural gas pipeline corridor through the upper Tanana valley (Reger and others, PIR 2008-3a) using Geographic Information System (GIS) software. Surficial-geologic units were initially identified by interpretation of false-color ~1:63,000-scale infrared aerial photographs taken in July 1978, August 1980, and August 1981 and locally verified by field checking in 2006 and 2007. The map shows the distribution of surficial-geologic and bedrock units grouped genetically with common properties that are typically significant for engineering applications.

This derivative engineering-geologic map illustrates potential near-surface sources of various geologic materials that may be useful for construction near the Dalton Highway area, from Atigun Gorge to Slope Mountain. The map area is located in the west-central Philip Smith Mountains quadrangle. The map extends from the northern flank of the Endicott Mountains into the Arctic Foothills province. Field observations indicate that each geologic unit (for example, stream alluvium) has a definite composition or range of composition. Therefore, the probable presence of materials is interpreted from the distribution of geologic units on the geologic map of this quadrangle. Map unit descriptions also include discussion of the potential geologic hazards that can be inferred from the typical physical properties of each map unit, such as sediment texture and ground-ice content and typical topographic settings. This map is generalized and is not intended to show exact locations of specific materials. Local variations are common, especially near unit boundaries. The map was derived electronically from a related surficial geologic map of the area using Geographic Information System (GIS) software. Geologic units were locally verified by ground observations during field visits. The results should be considered reconnaissance in nature.

This publication is a 6 CD-ROM compilation of data describing the bedrock, surficial, and engineering geology of a portion of the proposed Alaska Natural Gas Transportation System corridor. Maps or reports with scales of 1:250,000 or greater that cross or come within 5 miles of the centerline were included in this compilation. Two maps with scales smaller than 1:250,000 were also included: OFR 82-1071 and OFR 98-133. A complete bibliography of references used in this compilation is on the first CD-ROM of this project in ANGTSgis/RefsCited.doc. This project consists of an ArcView 3.x (AV) .apr file and a Microsoft Access 2000 (MS Access) database. The ArcView project and the Access database are linked using AccessLink, which runs from ArcView. A free, limited version of AccessLink is included with this compilation on the first CD-ROM in ANGTSgis/Extras/AccessLinkLTD.avx. This version of the ANGTS AV project and MS Access database covers the area from Prudhoe Bay to Delta Junction. Scanned versions of documents or maps are linked to the AV 3.x project and to the Access database.

During 2006 and 2007 the Alaska Division of Geological & Geophysical Surveys conducted reconnaissance surficial-geologic mapping in segment 1 of the Alaska Highway corridor, which straddles the Alaska Highway through the Tanana River valley from Delta Junction to the eastern boundary of the Mt. Hayes Quadrangle. Surficial-geologic deposits were initially mapped by interpreting ~1:63,360-scale, false-color infrared aerial photographs taken in August 1980 and field verified in 2006-2007.