Glacial Geology and Stratigraphy of Fort Richardson, Alaska. A Review of Available Data on the Hydrogeology

• Main Authors: Hunter, Lewis E., Lawson, Daniel E., Bigl, Susan R., Robinson, Peggy B., Schlagel, Joel D.
• Other Authors: COLD REGIONS RESEARCH AND ENGINEERING LAB HANOVER NH
• Format: Text
• Language: English
• Published: 2000
• Subjects: Geology; Geochemistry and Mineralogy; Snow; Ice and Permafrost; *GLACIERS; *GLACIAL GEOLOGY; ALASKA; STRATIGRAPHY; HYDROGEOLOGY; ELMENDORF MORAINE; ANCHORAGE(ALASKA) QUARTERNARY GEOLOGY; MOUNTAIN VIEW FAN; *GLACIAL STRATIGRAPHY; Anchorage; glaciers; Ice; permafrost; Alaska
• Online Access: http://www.dtic.mil/docs/citations/ADA378398; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA378398

The surficial geology and glacial stratigraphy of Fort Richardson are extremely complex. Recent mapping by the USGS shows the general distribution of surficial deposits, but details on the underlying stratigraphy remain poorly known, leaving a critical gap in the understanding of ground water conditions below Fort Richardson. A conceptual model of the subsurface stratigraphy was developed on the basis of results of recent surficial mapping, current knowledge of the glacial history studies of modern glaciers, and limited subsurface data. A confining layer below the southern half of the cantonment is likely the northern extension of an "older" ground moraine that crops out further to the south. Below the cantonment, this moraine is buried below about 15 m of outwash and fan deposits, but it appears to be absent to the north, where the confined and unconfined aquifers are hydraulically connected. The northern limit of the "continuous" ground moraine is roughly below the cantonment and parts of Operable Unit D. Buried silt horizons in the fan probably create the locally perched aquifers; however, erosional remnants of the ground moraine and interfingering of debris flow deposits along the Elmendorf Moraine are plausible alternatives. These deposits are composed of finer-grained materials that slow ground water infiltration and cause water to accumulate.