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At least 1,261 records · Page 70Linked to original sources
USGS1965

Hydrology of subsurface waste disposal, National Reactor Testing Station, Idaho: Annual progress report for 1964

The principal purpose of the past research program on geohydrology at the NRTS has been to acquire information on the physical and geochemical environment of the station. This requires a knowledge of the composition and structure of the earth materials underlying the plain, the inventory of the water resources, the dynamics of natural and man-produced changes in the hydrologic regimen, details of the hydrologic cycle, and relevant geochemical processes. The Geological Survey in the course of its early studies by Nace and others (IDO 22033-34-USGS) obtained, compiled, and analyzed a considerable amount of basic geologic and hydrologic information on these subjects. These basic goals were expanded and carried forward to guide the continuing research work. Jones (IDO 22042-USGS) emphasized the use of borehole geophysics and specialized down-hole techniques. Olmsted (IDO 22043-USGS) made a preliminary appraisal of the nature and distribution of the quality of ground water beneath the Station. Their work has been continued and elaborated upon by Morris and others (IDO 22044-USGS, 46-USGS) and the present report with greater emphasis on the regional geology and hydrology. This involved some procurement of needed information but, for the most part, involved a continued evaluation and refinement of data and results that had been acquired in the past. The Geological Survey also encouraged a more comprehensive study of the regional geologic structure including the use of aeromagnetic, gravity, and seismic geophysical techniques and cosponsored a seminar on it in 1964. Along with this investigation and study of the regional geology and of hydrologic principles operative in the basalt environment, and made possible because of it, research continues on the-hydrologic aspects of the disposal of low-level aqueous waste to the environment.

Idaho↗
USGS2010

Contamination of groundwater by the fumigants ethylene dibromide (EDB) and dibromochloropropane (DBCP) near McBee, South Carolina

McBee is a small town of about 700 people located in Chesterfield County, South Carolina, in the Sandhills region of the upper Coastal Plain. The halogenated organic compounds ethylene dibromide (EDB) and dibromochloropropane (DBCP) have been detected in several public and domestic supply and irrigation wells since 2002 at concentrations above their U.S. Environmental Protection Agency Maximum Contaminant Limits of 0.05 and 0.2 microgram per liter (µg/L), respectively. The source(s) and release histories of EDB and DBCP to local groundwater are unknown, but believed to be related to their historical use between the 1940s and their ban in the late 1970s as fumigants to control nematode damage in peach orchards. However, gasoline and jet-fuel supplies also contained EDB and are an alternative source of contamination to groundwater. The detection of EDB and DBCP in water wells has raised health concerns because groundwater is the sole source of water supply in the McBee area. In April 2010, forensic, geochemical-based investigation was initiated by the U.S. Geological Survey in cooperation with the Alligator Rural Water & Sewer Company to provide additional data regarding EDB and DBCP in local groundwater. The investigation includes an assessment of the use, release, and disposal history of EDB and DBCP in the area, the distribution of EDB and DBCP concentrations in the unsaturated zone, and transport and fate in groundwater.

South Carolina↗
USGS1963

Preliminary interpretation of an aeromagnetic survey in north-central Iowa

Publication of Lyons' gravity map of the United States in 1950 focused attention on a spectacular geophysical feature now generally referred to as the "midcontinent gravity high." This feature, the largest gravity maximum in North America, was discovered and later detailed by geophysicists at the University of Wisconsin (Woollard, 1943, 1951) and Thiel (1956). Their work reveals an essentially continuous large positive gravity anomaly extending southwestward for 800 miles from Lake Superior to the Salina Basin in Kansas. The midcontinent gravity high reaches its maximum intensity in central Iowa where the Bouguer anomaly ranges from -100 to 60 milligals. In September-October 1961, the U. S. Geological Survey made a 5,000 square mile aeromagnetic survey in north-central Iowa in cooperation with the Iowa Geological Survey. Objectives of the investigation were to prepare and interpret a detailed aeromagnetic contour map for part of the midcontinent gravity high in Iowa. Analysis of the magnetic data could be expected to yield estimates of local thickness of the Paleozoic-Mesozoic sedimentary section and provide a basis for informed speculation about the character, configuration, and distribution of the Precambrian rocks. Such information would have obvious scientific and possible economic value in an area covered by glacial till and for which little deep subsurface knowledge was available. Interpretation of the Indiana aeromagnetic survey (Henderson and Zietz, 1958) had previously demonstrated that aeromagnetic data from the central stable region of North America would provide a significant amount of geologic information. The 5,000 square mile area surveyed in 1961 has been combined with a previously unpublished 600 square mile aeromagnetic survey made in 1953, centered on Manson, Pocahontas Co., Iowa. The combined area is shown as the patterned area in figure 1. The unpatterned area outlined on this same figure is the additional 10,000 square mile cooperative aeromagnetic survey made in the summer of 1962 to complete coverage of the midcontinent gravity high in Iowa. The primary purpose of this report is to make the 1953 and 1961 aeromagnetic data available to the public in advance of more formal publication. Only salient magnetic features are discussed in this preliminary presentation and in a second report on results obtained during the 1962 flying. A more complete interpretation of the entire aeromagnetic survey will be prepared.

Iowa↗
USGS2002

Results of Hydraulic Tests in Miocene Tuffaceous Rocks at the C-Hole Complex, 1995 to 1997, Yucca Mountain, Nye County, Nevada

Four hydraulic tests were conducted by the U.S. Geological Survey at the C-hole complex at Yucca Mountain, Nevada, between May 1995 and November 1997. These tests were conducted as part of ongoing investigations to determine the hydrologic and geologic suitability of Yucca Mountain as a potential site for permanent underground storage of high-level nuclear waste. The C-hole complex consists of three 900-meter-deep boreholes that are 30.4 to 76.6 meters apart. The C-holes are completed in fractured, variably welded tuffaceous rocks of Miocene age. Six hydrogeologic intervals occur within the saturated zone in these boreholes - the Calico Hills, Prow Pass, Upper Bullfrog, Lower Bullfrog, Upper Tram, and Lower Tram intervals. The Lower Bullfrog and Upper Tram intervals contributed about 90 percent of the flow during hydraulic tests. The four hydraulic tests conducted from 1995 to 1997 lasted 4 to 553 days. Discharge from the pumping well, UE-25 c #3, ranged from 8.49 to 22.5 liters per second in different tests. Two to seven observation wells, 30 to 3,526 meters from the pumping well, were used in different tests. Observation wells included UE-25 c #1, UE-25 c #2, UE-25 ONC-1, USW H-4, UE-25 WT #14, and UE-25 WT #3 in the tuffaceous rocks and UE-25 p #1 in Paleozoic carbonate rocks. In all hydraulic tests, drawdown in the pumping well was rapid and large (2.9-11 meters). Attributable mostly to frictional head loss and borehole-skin effects, this drawdown could not be used to analyze hydraulic properties. Drawdown and recovery in intervals of UE-25 c #1 and UE-25 c #2 and in other observation wells typically was less than 51 centimeters. These data were analyzed. Hydrogeologic intervals in the C-holes have layered heterogeneity related to faults and fracture zones. Transmissivity, hydraulic conductivity, and storativity generally increase downhole. Transmissivity ranges from 4 to 1,600 meters squared per day; hydraulic conductivity ranges from 0.1 to 50 meters per day; and storativity ranges from 0.00002 to 0.002. Transmissivity in the Miocene tuffaceous rocks decreases from 2,600 to 700 meters squared per day northwesterly across the 21-square-kilometer area affected by hydraulic tests at the C-hole complex. The average transmissivity of the tuffaceous rocks in this area, as determined from plots of drawdown in most or all observation wells as functions of time or distance from the pumping well, is 2,100 to 2,600 meters squared per day. Average storativity determined from these plot ranges is 0.0005 to 0.002. Hydraulic conductivity ranges from less than 2 to more than 10 meters per day; it is largest where prominent northerly trending faults are closely spaced or intersected by northwesterly trending faults. During hydraulic tests, the Miocene tuffaceous rocks functioned as a single aquifer. Drawdown occurred in all monitored intervals of the C-holes and other observation wells, regardless of the hydrogeologic interval being pumped. This hydraulic connection across geologic and lithostratigraphic contacts is believed to result from interconnected faults, fractures, and intervals with large matrix permeability. Samples of UE-25 c #3 water, analyzed from 1995 to 1997, seem to indicate that changes in the quality of the water pumped from that well are probably due solely to lateral variations in water quality within the tuffaceous rocks.

Water-Resources Investigations Report↗
USGS1946

Stratigraphy and structure of the area of the Killik, Chandler, Anaktuvuk, and Colville Rivers, Alaska

This report deals with results of field and laboratory studies carried out to May 1946 by the Geological Survey, largely as part of the Navy Department's program of petroleum investigations in northern Alaska. The immediate purpose of the work has been to collect and interpret stratigraphic and structural data pertinent to drilling in the Umiat area. Field studies were made during the summers of 1944 and 1945 in the drainage areas of the Colville, Killik, Chandler, and. Anaktuvuk Rivers (fig. 1). Paleontologic and microlithologic studies, together with stratigrahica1 and structural analysis of the areas, were carried out in the petroleum laboratory in Fairbanks. This work led. to preparation of a preliminary report submitted. in December, 1945. Additional detailed studies, in the Survey laboratories and offices in Washington, D. C., have resulted in some modification of earlier conclusions and changes in illustrations. The changes are minor and have no significant bearing on drilling in the Umiat area. The present report is accompanied. by revised conies of figures 1, 2, 3 (sheet 1) and. 5. These illustrations should be substituted for the comparable figures of the preliminary report. Figures 3 (sheet 2), 4, and. 6 of the earlier report stand unchanged and should, be added to the illustrations accompanying the present report. It is believed that work to date has revealed the general geologic picture of the area and. that the sequence of Upper Cretaceous rocks is established. The section of rocks in Umiat Test No. 1 has been approximately located within the sequence. This report, and the work on which it is based was done under the supervision of George O. Gates, who has contributed. much to the study.

Alaska↗
USGS2009

USGS Water Data for Washington

The U.S. Geological Survey (USGS) has been investigating the water resources of Washington State since the latter part of the 19th century. During this time, demand for water has evolved from primarily domestic and stock needs to the current complex requirements for public-water supplies, irrigation, power generation, navigation, ecological needs, and numerous other uses. Water-resource data collected by the USGS in Washington have been, or soon will be, published by the USGS Washington Water Science Center (WAWSC) in numerous data and interpretive reports. Most of these reports are available online at the WAWSC web page http://wa.water.usgs.gov/pubs/

Fact Sheet↗
USGS1973

Photomechanical experiments in automated cartography

The U.S. Geological Survey recently undertook the investigation of two seemingly unrelated cartographic tasks: (1) the preparation of map copy for digitizing and (2) the production of experimental slope maps. Both tasks, however, require techniques and equipment for changing or manipulating the line weights of existing map symbols and producing suitable reproduction copy. After a study of existing equipment, a prototype revolving illuminator was designed and fabricated for experiments in line-weight manipulation. Sufficient exposures have been made with the device to indicate that positive control of line-weight increases and decreases up to 0.2 inch is attainable. The device has been used for photomechanical experiments in slope mapping, hill shading, and preparation of map copy for digitizing.

Journal of Research of the U.S. Geological Survey↗
USGS1991

The Conterminous United States Mineral Appraisal Program; background information to accompany folio of geologic, geochemical, geophysical, and mineral resources maps of the Tonopah 1 by 2 degree Quadrangle, Nevada

The Tonopah 1 ? by 2 ? quadrangle in south-central Nevada was studied by an interdisciplinary research team to appraise its mineral resources. The appraisal is based on geological, geochemical, and geophysical field and laboratory investigations, the results of which are published as a folio of maps, figures, and tables, with accompanying discussions. This circular provides background information on the investigations and integrates the information presented in the folio. The selected bibliography lists references to the geology, geochemistry, geophysics, and mineral deposits of the Tonopah 1 ? by 2 ? quadrangle.

Circular↗
USGS1992

The Conterminous United States Mineral Assessment Project; background information to accompany folio of geologic, geochemical, geophysical, and mineral resources maps of the Reno 1 by 2 degree Quadrangle, Nevada and California

The Reno 1 ? by 2 ? quadrangle in west-central Nevada was studied by an interdisciplinary research team to appraise its mineral resources. The assessment is based on geological, geochemical, and geophysical field and laboratory investigations, the results of which are published as a folio of maps, reports, figures, and tables, with accompanying discussions. This circular provides background information on the investigations and integrates the information presented in the folio. The selected bibliography lists references to the geology, geochemistry, geophysics, and mineral deposits of the Reno 1 ? by 2 ? quadrangle.

Circular↗
USGS1986

The Conterminous United States Mineral Appraisal Program; background information to accompany folio of geologic, geochemical, geophysical, and mineral resources maps of the Medford 1 degree x 2 degrees Quadrangle, Oregon and California

The Medford 1 ? by 2 ? quadrangle in southern Oregon and northern California was studied by an interdisciplinary research team to appraise its mineral resources. The appraisal is based on geological, geochemical, and geophysical field and laboratory investigations, the results of which are published as a folio of maps, figures, and tables, with accompanying discussions. This circular provides background information on the investigations and integrates the information presented in the folio. The bibliography lists selected references to the geology, geochemistry, geophysics, and mineral deposits of the Medford 1 ? by 2 ? quadrangle.

Circular↗
USGS2000

Ground-water conditions in Georgia, 1999

Ground-water conditions in Georgia during 1999 and for the period of record were evaluated using data from U.S. Geological Survey ground-water-level and ground-water-quality monitoring networks. Data for 1999 included in this report are from continuous water-level records from 130 wells and chloride analyses from 14 wells. Data from one well is incomplete because data collection was discontinued. Chloride concentration in water from the Upper Floridan aquifer in most of coastal Georgia was within drinking-water standards established by the Georgia Department of Natural Resources and the U.S. Environmental Protection Agency. In the Savannah area, chloride concentration has not changed appreciably with time. However, chloride concentration in water from some wells that tap the Floridan aquifer system in the Brunswick area exceeds the drinking-water standards. Ground-water-level and ground-water-quality data are essential for water assessment and management. Ground-water-level fluctuations and trends can be used to estimate changes in aquifer storage resulting from the effects of ground-water withdrawal and recharge from precipitation. These data can be used to address water-management needs and to evaluate the effects of management and conservation programs. As part of the ground-water investigations conducted by the U.S. Geological Survey (USGS), in cooperation with the State of Georgia and city and county governments, a Statewide water-level-measurement program was started in 1938. Initially, this program consisted of an observation-well network in the coastal area of Georgia to monitor variations in ground-water storage and quality. Additional wells were later included in areas where data could be used to aid in water resources development and management. During 1999, periodic water-level measurements were made in 46 wells, and continuous water-level measurements were obtained from 165 wells. Continuous water-level records were obtained using analog (pen and chart) recorders and electronic data recorders that record the water level at 60-minute intervals. For wells having incomplete water-level record, water levels during periods of missing record may have been higher or lower than recorded water levels. Water samples collected from 85 wells during May, June, July, August, September, October, November, and December 1999 were analyzed to determine chloride concentration in the Savannah and Brunswick areas.

Georgia↗
USGS2006

Investigation of the hydrologic monitoring network of the Willcox and Douglas Basins of southeastern Arizona: A project of the Rural Watershed Initiative

In 2005, the U.S. Geological Survey (USGS), in cooperation with the Arizona Department of Water Resources (ADWR), began an investigation of the geology and hydrology of the Willcox and Douglas Basins (primarily focusing on the hydrologic monitoring network) as part of the Rural Watershed Initiative (RWI). The purpose of this study is to evaluate the data-collection network that is used to monitor hydrologic conditions and ground-water storage changes in the Willcox and Douglas Basins.

Arizona↗
USGS1924

The composition of the river and lake waters of the United States

In the summer of 1903 the late Richard B. Dole, chemist of the water-resources branch of the United States Geological Survey, began a systematic investigation of the composition of the river and lake waters of the United States. His plan, which developed gradually, was to have analyses made of the different waters in such a manner as to give the average composition of each one for an entire year. For a few waters, such completeness was impracticable, the analyses covered only part of a year, but even in these waters the data obtained were of much value. As a rule, samples of each water were collected day by day. They were then mixed in sets of ten and analyzed, so that for each river or lake from 34 to 37 analyses were made. For the Mississippi above New Orleans composite analyses were made in sets of seven, giving 52 analyses from which to compute the average. For the Great Lakes, however, only monthly samples were taken, for the reason that their waters vary so little in composition that greater elaboration was not necessary. Some of the larger rivers were treated even more thoroughly; their average composition was determined at more than one point – the Mississippi at six points. For some rivers the analyses cover two years of collection, and for the data, received from a contributor not connected with the Geological Survey, three years.

Professional Paper↗
USGS2009

Pore-water chemistry from the ICDP-USGS coer hole in the Chesapeake Bay impact structure--Implications for paleohydrology, microbial habitat, and water resources

We investigated the groundwater system of the Chesapeake Bay impact structure by analyzing the pore-water chemistry in cores taken from a 1766-m-deep drill hole 10 km north of Cape Charles, Virginia. Pore water was extracted using high-speed centrifuges from over 100 cores sampled from a 1300 m section of the drill hole. The pore-water samples were analyzed for major cations and anions, stable isotopes of water and sulfate, dissolved and total carbon, and bioavailable iron. The results reveal a broad transition between fresh and saline water from 100 to 500 m depth in the post-impact sediment section, and an underlying syn-impact section that is almost entirely filled with brine. The presence of brine in the lowermost post-impact section and the trend in the dissolved chloride with depth suggest a transport process dominated by molecular diffusion and slow, compaction-driven, upward flow. Major ion results indicate residual effects of diagenesis from heating, and a pre-impact origin for the brine. High levels of dissolved organic carbon (6-95 mg/L) and the distribution of electron acceptors indicate an environment that may be favorable for microbial activity throughout the drilled section. The concentration and extent of the brine is much greater than had previously been observed, suggesting its occurrence may be common in the inner crater. However, groundwater flow conditions in the structure may reduce the salt-water-intrusion hazard associated with the brine.

Special Paper of the Geological Society of America↗
USGS1991

Biomarkers in Tertiary mélange, western Olympic Peninsula, Washington, U.S.A.

Middle Eocene to middle Miocene mélange and broken formations are exposed in the coastal outcrops along the west side of the Olympic Peninsula, Washington. A petroleum geochemical assessment of these geologic units has included the investigation of biomarker compounds. A comparison was made of biomarkers in an oil sample from a middle Miocene reservoir penetrated in the Medina No. 1 well with biomarkers in extracts from two samples of middle Eocene Ozette mélange (one sample having a strong petroliferous odor, and the other sample lacking this characteristic odor). Distribution patterns of n -alkanes, tricyclic terpanes, pentacyclic triterpanes, steranes, and diasteranes are remarkably similar in the oil and rock extracts. Biomarker maturity parameters indicate higher maturity in the oil relative to the extracts. The presence of 17α(H)-23,28-bisnorlupane, 18α(H)- and 18β(H)-oleanane, and de-A-lupane and an odd-carbon-number dominance of the n -alkanes in the oil and extracts seems to tie the hydrocarbons to a common source that has a significant terrigenous component.

Chemical Geology↗
USGS2003

Raster dataset showing the probability of elevated concentrations of nitrate in ground water in Colorado, hydrogeomorphic regions and fertilizer use estimates included

This dataset is one of eight datasets produced by this study. Four of the datasets predict the probability of detecting atrazine and(or) desethyl-atrazine (a breakdown product of atrazine) in ground water in Colorado; the other four predict the probability of detecting elevated concentrations of nitrate in ground water in Colorado. The four datasets that predict the probability of atrazine and(or) desethyl-atrazine (atrazine/DEA) are differentiated by whether or not they incorporated atrazine use and whether or not they incorporated hydrogeomorphic regions. The four datasets that predict the probability of elevated concentrations of nitrate are differentiated by whether or not they incorporated fertilizer use and whether or not they incorporated hydrogeomorphic regions. Each of the eight datasets has its own unique strengths and weaknesses. The user is cautioned to read Rupert (2003, Probability of detecting atrazine/desethyl-atrazine and elevated concentrations of nitrate in ground water in Colorado: U.S. Geological Survey Water-Resources Investigations Report 02-4269, 35 p., http://water.usgs.gov/pubs/wri/wri02-4269/) to determine if he(she) is using the most appropriate dataset for his(her) particular needs. This dataset specifically predicts the probability of detecting elevated concentrations of nitrate in ground water in Colorado with hydrogeomorphic regions and fertilizer use included. The following text was extracted from Rupert (2003). Draft Federal regulations may require that each State develop a State Pesticide Management Plan for the herbicides atrazine, alachlor, metolachlor, and simazine. Maps were developed that the State of Colorado could use to predict the probability of detecting atrazine/DEA in ground water in Colorado. These maps can be incorporated into the State Pesticide Management Plan and can help provide a sound hydrogeologic basis for atrazine management in Colorado. Maps showing the probability of detecting elevated nitrite plus nitrate as nitrogen (nitrate) concentrations in ground water in Colorado also were developed because nitrate is a contaminant of concern in many areas of Colorado. Maps showing the probability of detecting atrazine/DEA at or greater than concentrations of 0.1 microgram per liter and nitrate concentrations in ground water greater than 5 milligrams per liter were developed as follows: (1) Ground-water quality data were overlaid with anthropogenic and hydrogeologic data by using a geographic information system (GIS) to produce a dataset in which each well had corresponding data on atrazine use, fertilizer use, geology, hydrogeomorphic regions, land cover, precipitation, soils, and well construction. These data then were downloaded to a statistical software package for analysis by logistic regression. (2) Relations were observed between ground-water quality and the percentage of land-cover categories within circular regions (buffers) around wells. Several buffer sizes were evaluated; the buffer size that provided the strongest relation was selected for use in the logistic regression models. (3) Relations between concentrations of atrazine/DEA and nitrate in ground water and atrazine use, fertilizer use, geology, hydrogeomorphic regions, land cover, precipitation, soils, and well-construction data were evaluated, and several preliminary multivariate models with various combinations of independent variables were constructed. (4) The multivariate models that best predicted the presence of atrazine/DEA and elevated concentrations of nitrate in ground water were selected. (5) The accuracy of the multivariate models was confirmed by validating the models with an independent set of ground-water quality data. (6) The multivariate models were entered into a geographic information system and the probability GRIDS were constructed.

Open-File Report↗
USGS2009

Cone penetration test and soil boring at the Bayside Groundwater Project Site in San Lorenzo, Alameda County, California

Aquifer-system deformation associated with ground-water-level changes is being investigated cooperatively by the U.S. Geological Survey (USGS) and the East Bay Municipal Utility District (EBMUD) at the Bayside Groundwater Project (BGP) near the modern San Francisco Bay shore in San Lorenzo, California. As a part of this project, EBMUD has proposed an aquifer storage and recovery (ASR) program to store and recover as much as 3.78x104 m3/d of water. Water will be stored in a 30-m sequence of coarse-grained sediment (the 'Deep Aquifer') underlying the east bay alluvium and the adjacent ground-water basin. Storing and recovering water could cause subsidence and uplift at the ASR site and adjacent areas because the land surface will deform as aquifers and confining units elastically expand and contract with ASR cycles. The Deep Aquifer is overlain by more than 150 m of clayey fine-grained sediments and underlain by comparable units. These sediments are similar to the clayey sediments found in the nearby Santa Clara Valley, where inelastic compaction resulted in about 4.3 m of subsidence near San Jose from 1910 to 1995 due to overdraft of the aquifer. The Deep Aquifer is an important regional resource, and EBMUD is required to demonstrate that ASR activities will not affect nearby ground-water management, salinity levels, or cause permanent land subsidence. Subsidence in the east bay area could induce coastal flooding and create difficulty conveying winter storm runoff from urbanized areas. The objective of the cooperative investigation is to monitor and analyze aquifer-system compaction and expansion, as well as consequent land subsidence and uplift resulting from natural causes and any anthropogenic causes related to ground-water development and ASR activities at the BGP. Therefore, soil properties related to compressibility (and the potential for deformation associated with ground-water-level changes) are of the most concern. To achieve this objective, 3 boreholes were drilled at the BGP for the purpose of monitoring pore-fluid pressure changes and aquifer-system deformation. One 308-m deep borehole contains six piezometers, the other two boreholes are 182 and 299 m deep and contain a dual-stage extensometer. To investigate the physical properties of the sediments, two phases of subsurface exploration were conducted. In the first phase, a USGS drilling crew obtained numerous core samples, 5.8 cm in diameter by 1.5 m long. The samples were extracted between July 28, 2006, and August 5, 2006; nine samples were tested for this study at the USGS soils laboratory in Menlo Park, California. Phase two began on June 22, 2006, when a seismic cone penetration test (SCPT) sounding was made to a depth of 32.3 m. Additional field work was completed May 8, 2007, with a hollow-stem auger boring that took continuous 9.8-cm-diameter samples from the depth interval of 6.1 to 10.7 m to supplement poor recovery from the first phase of sampling. These samples were also tested in the soils laboratory at the USGS.

California↗