13 research outputs found
UNITED STATES DEPARTMENT OF THE INTERIOR GEOLOGICAL SURVEY AERIAL PHOTOGRAPHIC INTERPRETATION OF LINEAMENTS AND FAULTS IN LATE CENOZOIC DEPOSITS IN THE EASTERN PART OF THE BENTON RANGE 1:100,000 QUADRANGLE AND THE GOLDFIELD, LAST CHANCE RANGE, BEATTY, AND
ABSTRACT Lineaments and faults in Quaternary and late Tertiary deposits in the southern part of the Walker Lane are potentially active and form patterns that are anomalous with respect to the typical fault patterns in most of the Great Basin. Little work has been done to identify and characterize these faults, with the exception of those in the Death ValleyFurnace Creek (DVFCFZ) fault system and those in and near the Nevada Test Site. Four maps at a scale of 1:100,000 summarize the existing knowledge about these lineaments and faults based on extensive aerial-photo interpretation, limited field investigations, and published geologic maps. The lineaments and faults in all four maps can be divided geographically into two groups. The first group includes west-to north-trending lineaments and faults associated with the DVFCFZ and with the Pahrump fault zone in the Death Valley Junction quadrangle. The second group consists of north-to east-northeast-trending lineaments and faults in a broad area that lies east of the DVFCFZ and north of the Pahrump fault zone. Preliminary observations of the orientations and sense of slip of the lineaments and faults suggest that the least principal stress direction is west-east in the area of the first group and northwest-southeast in the area of the second group
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Rillenkarren at Vayia: geomorphology and a new class of Early Bronze Age fortified settlement in Southern Greece
With ever more inhibited programmes of excavation, new methods of site survey are always
welcome. Here a soil geomorphologist joins forces with archaeologists to read the history of
limestone blocks exposed on the surface at sites in southern Greece. Rillenkarren for example are
vertical grooves caused by rainfall on stones that remained for long periods in the same place.
These and other observations showed that what looked like clearance cairns had in fact been piled
up in the Early Bronze Age and led in turn to the definition of a new type of settlementKeywords: fortifications, stone cairns, karst geomorphology, Greece, Early Bronze AgeKeywords: fortifications, stone cairns, karst geomorphology, Greece, Early Bronze Ag
Incidence and Tracking of Escherichia coli O157:H7 in a Major Produce Production Region in California
Fresh vegetables have become associated with outbreaks caused by Escherichia coli O157:H7 (EcO157). Between 1995–2006, 22 produce outbreaks were documented in the United States, with nearly half traced to lettuce or spinach grown in California. Outbreaks between 2002 and 2006 induced investigations of possible sources of pre-harvest contamination on implicated farms in the Salinas and San Juan valleys of California, and a survey of the Salinas watershed. EcO157 was isolated at least once from 15 of 22 different watershed sites over a 19 month period. The incidence of EcO157 increased significantly when heavy rain caused an increased flow rate in the rivers. Approximately 1000 EcO157 isolates obtained from cultures of>100 individual samples were typed using Multi-Locus Variable-number-tandem-repeat Analysis (MLVA) to assist in identifying potential fate and transport of EcO157 in this region. A subset of these environmental isolates were typed by Pulse Field Gel Electrophoresis (PFGE) in order to make comparisons with human clinical isolates associated with outbreak and sporadic illness. Recurrence of identical and closely related EcO157 strains from specific locations in the Salinas and San Juan valleys suggests that transport of the pathogen is usually restricted. In a preliminary study, EcO157 was detected in water at multiple locations in a low-flow creek only within 135 meters of a point source. However, possible transport up to 32 km was detected during periods of higher water flow associated with flooding. During the 2006 baby spinach outbreak investigation, transport was also detected where water was unlikely to be involved. These results indicate that contamination of the environment is a dynamic process involving multiple sources and methods of transport. Intensive studies of the sources, incidence, fate and transport of EcO157 near produce production are required to determine the mechanisms of pre-harvest contamination and potential risks for human illness
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Artificial means of distinguishing smooth-line map unit boundaries : an examination of Oregon soil survey maps
This data set is used in the Master thesis of Yulin Sun (2017). It contains geospatial vector data (shapefiles), Microsoft Excel spreadsheets, and Portable Document Format (PDF) files. The geospatial vector data include both the data of original soil delineations and that of the convex hull of individual soil delineations. The attribute tables of these vector data contain the primary parameters that have been used to calculate shape descriptors. The Microsoft Excel spreadsheets contain values of calculated shape descriptors for each soil delineations and their corresponding convex hulls. The PDF files contains the R codes to conduct the statistical analyses on the data set. The statistical analyses used in Sun's thesis are kernel density estimation, two sample Kolmogorov–Smirnov test (ks test), and scatter plot
Water Use and Soil Moisture Relationships on Western Juniper Trees at Different Growth Stages
An enhanced understanding of plant water uptake is critical for making better-informed management decisions involving vegetative manipulation practices aimed to improve site productivity. This is particularly true in arid and semiarid locations where water is a scarce, yet precious commodity. In this project, we evaluated the interannual and seasonal variability of soil moisture and transpiration in sapling, juvenile, and mature western juniper (Juniperus occidentalis) trees in a semiarid rangeland ecosystem of central Oregon, USA. Transpiration levels were greatest in mature juniper trees in an untreated juniper watershed (Jensen WS), while the lowest transpiration levels were observed in juniper saplings in a treated watershed (Mays WS) where most mature juniper trees were removed in 2005. Significant differences (p ≤ 0.05) in leaf water potential levels observed between predawn and midday readings for all juniper growth stages indicated water is lost over the course of the day. Results showed seasonal precipitation was highly variable over the course of the study (2017 through 2019) and this was reflected in soil water available for tree uptake. This resulted in considerable intra- and inter-annual variation in transpiration. In years with greater winter precipitation amounts (2017 and 2019), juniper transpiration rates were highest during the summer, followed by spring, autumn, and winter. On average, transpiration rates during the summer in the wettest (329 mm) year 2017 were 115 and 2.76 L day−1 for mature and sapling trees, respectively. No data were collected for juvenile trees in 2017. In the drier (245 mm) year 2018, higher transpiration rates were observed in the spring. On average, spring transpiration rates were 72.7, 1.61, and 1.00 L day−1 for mature, juvenile, and sapling trees, respectively. Study results highlight the sensitivity of western juniper woodlands to variations in seasonal precipitation and soil moisture availability