Geology topics

Larry L. Dearborn

Publications and source records attributed to Larry L. Dearborn.

4 recordsLinked to original sources

USGS1983

Preliminary lithologic, geotechnical, and geophysical data from drill hole CW-81-2, Chuitna West coal field, Cook Inlet region, Alaska

The drilling and logging activity described in this report was undertaken in July 1981, as part of the Energy Lands program of the U.S. Geological Survey. The general objectives of the project of which this work is a part are to provide an understanding of the nature, location, and extent of the engineering geology and environmental geology concerns in areas of potential coal development in the Cook Inlet region, Alaska. The lithologic, geotechnical, and geophysical data presented in this report include some of the data needed to evaluate geologic hazards, and to predict the response of geologic materials to large-scale coal mining and related development in the Chuitna West coal field of the Beluga coal resource area. Specifically, the information may be used in evaluation of natural- and cut-slope stability, spoil-pile stability, ground response to seismic activity, blasting effects, excavatability, ground-water conditions, and erosion potential. The drill site (fig. 1, point C), located on the edge of a small, gently sloping basin draining northwestward into the Chuitna River, is approximately 90 km, (55 mi) west of Anchorage, Alaska, and 29 km (18 mi) northwest of Tyonek, a native village on the northwest side of Cook Inlet.

Alaska↗

USGS1982

Preliminary geotechnical and geophysical logs from drill hole 2C-80 in the Capps coal field, Cook Inlet region, Alaska

The drilling and logging information provided in this report was collected during September 1980 as part of the Energy Lands program of the U.S. Geological Survey. Drill hole 2C-80 is located in the Capps Coal Field, approximately 100 km (62 mi) west of Anchorage, Alaska (fig. 1). The drilling was undertaken to obtain information on the geotechnical characteristics of a part of the coal-bearing Tyonek Formation and overlying surficial deposits. The preliminary results of a previous drill hole (1C-79), located 1.3 km (0.8 mi) northeast of drill hole 2C-80, were reported by Chleborad and others (1980). The Tyonek Formation is early Oligocene to middle Miocene in age (Wolfe and Tanai, 1980). At the drill site it is overlain by a thin colluvial deposit of Quaternary age. The drilling and continuous core sampling penetrated 19.5 m (63.9 ft) of overburden, a major coal bed (Waterfall bed), and approximately 29 m (95.1 ft) of underlying material, to a total depth of 61 m (200 ft). Drill hole 2C-80 stratigraphically overlaps drill hole 1C-79 and continues down section approximately 33 m (108 ft). A proposed open pit coal-mining plan (Placer Amex, Inc., 1977, status report of December 1977) outlines a sequential mining and reclamation scheme for five areas in the Capps Coal Field. Figure 2 shows the location of drill holes 2C-80 and 1C-79 with respect to the proposed mining areas as well as selected surface features. A general description of the geology and natural hazards of the region are given by Schmoll and others (1981). The generalized lithology interpreted from core obtained from drilling and supplemented by outcrop mapping accomplished during the 1979 and 1980 field seasons is presented in figure 3. A more detailed lithologic log is presented as part of the geotechnical log. The geotechnical and geophysical logs presented herein (pls. 1 and 2) provide basic physical-property and engineering data useful in predicting the response of geologic materials to proposed large-scale coal mining and related development, and in identifying and assessing potential geologic hazards.

Alaska↗

USGS1979

Water resources data of the Seward area, Alaska

Favorable geohydrologic conditions in the Seward area provide several choices for developing additional water supplies. Abundant stream runoff and the prospects for expanded well-field development in the Jap Creek alluvial fan, as well as other similar fans, allow a selection of future water sources based on factors other than the availability of the natural resource. Although water in both streams and deep aquifers is of good potable quality, ground water has the inherent advantages of being free of suspended sediment, of being warmer during winter months, and of being less vulnerable to pollution. Shallow infiltration galleries constructed along the alluvial-fan reaches of some streams should provide large volumes of water for public supply. A potential exists at Seward for serious flooding of the alluvial fans by the major streams, for coastal flooding by bay waters resulting from storm-driven waves or tsunamis, and for pollution of shallow ground water by onsite sewage disposal.

Alaska↗

USGS1975

Hydrology for land-use planning: The Hillside area, Anchorage, Alaska

Rapid residential growth of the Hillside area, Anchorage, Alaska, may cause depletion of aquifers and a change in quality of water resources as a result of extensive development of small-lot tracts. Ground-water yields are low and may be locally inadequate for single family requirements where wells produce from bedrock in the eastern Hillside region. At lower altitudes single family water requirements of 3 to 10 gallons per minute or 0.2 to 0.6 litre per second usually can be obtained, but aquifers capable of being pumped at larger yields for public supplies are uncommon. However, in a few localities, wells do produce 40 to 300 gallons per minute or 2.5 to 19 litres per second from sand and gravel aquifers lying within thick sequences of glacial till. Streamflow within the Hillside area is inadequate as a significant source of water for public supply. Springs, swamps, and water-logged surficial sediments in the Hillside area are mainly caused by hilly terrain and low permeability of surficial materials. The relative vulnerability of streams, lakes, and ground water to pollution caused by the discharge of liquid waste, particularly from onsite sewage-disposal systems, is moderate to high in about half the study area. At higher altitudes contamination of bedrock aquifers may occur if discharge of liquid wastes is not regulated. The deep sedimentary aquifers at lower altitudes are less susceptible to contamination. However, shallow groundwater bodies may become polluted by discharge of sewage effluent and, consequently, some deep wells may be contaminated by seepage down the outside of casings or through leaky casing joints and underground seals.

Alaska↗