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At least 523 records · Page 29Linked to original sources
USGS1981

Water resources data for Virginia, water year 1980

Water resources data for the 1980 water year for Virginia consist of records of stage, discharge, and water quality of streams; stage, contents, and water quality of lakes and reservoirs; and water levels and water quality of ground-water wells. This volume contains records for water discharge at 210 gaging stations; stage only at 1 gaging station; stage and contents at 10 lakes and reservoirs; water quality at 53 gaging stations and 120 wells; and water levels at 60 observation wells. Also included are data for 63 crest-stage partial-record stations. Locations of these sites are shown on figures 3 and 4. Additional water data were collected at various sites not involved in the systematic data-collection program. Discharge measurements were made at 142 coal-monitoring partial-record stations and 67 low-flow partial-record stations. Miscellaneous data were collected at 311 measuring sites and 186 water-quality sampling sites. These data represent that part of the National Water Data System collected by the U.S. Geological Survey and cooperating State and Federal agencies in Virginia.

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USGS1981

Biological and economic impact of stream alteration in the Virginia Piedmont

A 31 month (September 1974 - March 1977) study was conducted on warmwater streams located in the Roanoke Creek watershed of the Piedmont Region of Virginia. The purpose of the study was to determine the effects of stream channelization on the aquatic/riparian wildlife resource and agricultural land-use patterns associated with the altered streams. Three streams, which were channelized 3, 6, and 10 years prior to initiation of the study, and teo unaltered streams, were selected as representative streams for the study. Recently channelized streams lacked overstory cover but has an abundance of herbaceous and small woody plany cover, Conversely, control streams had significantly larger percentages of trees over 46 m tall. Plant species diversity, foliage height diversity, and evenness diversity increased as age since channelization increased. No major differences in water quality parameters were found for either channelized or control streams, although channelized streams had greater deposits of sand and lesser amount of rock, rubble, and gravel. These changes in substrate composition did not significantly modify actual stream flow rates. Fish species composition and species diversity among channelized and unchannelized streams were only slightly different, with most of the differences probably attributable to strays from adjacent habitats, However, evenness diversity for fish communities was lower in channelized streams. The benthic population showed greater changes than did the fish populations with an increase in Chironominae tolerant of unstable sand substrates in channelized streams. Evenness diversity of benthic populations was also higher and showed more consistency in the control stream than in channelized streams. Evenness diversity of benthic communities in control stream averaged between 0.5 to 0.6 and was quite consistent; whereas, the average in the two youngest channelized streams was 0.3 to 0.4. These data seem to indicate decreased stability of the biota in altered streams. In general, benthic macroinvertabrate and fish community parameters collected from channelized streams located 1200 m below a reservoir were either comparable to, or intermediate between, upstream (unchannelized) and reservoir tailwater values. The shallow surface discharge impoundments associated with channelized streams appeared to have a highly localized impact on the downstream benthic marcoinvertabrate and fish communities. During winter, bird species diversity (BSD) among channelized stream sites was not significantly different. During the breeding season, species richness (number of breeding species) and BSD increased with age since channelization. Breeding bird densities were 6.2 pairs/ha in the most recent (3 yr) channelized site and 13.3 pairs/ha on the control streams. Bird diversity and density, particularly for Parulids (warblers), during the breeding season were reduced significantly by removal of tree and shrub layers along channelized streams. No significant differences were found among study sites for either total number of small mammals or their species diversity indices; although, there was a trend toward increasing diversity as age since channelization increased. Smaller differences in species diversity values for small mammals on channelized sites than for birds suggests that small mammal populations require less time for recovery following channelization than avian communities. When streams are channelized: 1) vegetation should be removed from only one side of the stream, with minimal disturbance of top-soil; followed by plantings of herbaceous and woody vegetation, 2) hedgrow plantings should be maintained between agricultural fields and the stream for bank stabilization, 3) dead snags and large trees should be left for birds, 4) all channelization projects should be designed according to the most recent guidelines recommended by the SCS and other resources agencies. In 1958, the Roanoke County Watershed Work Plan projected annual costs of the structured measures (mainly reservoirs and downstream channelization) to be $79,897 and the average annual monetary benefits to be $111,103. With this favorable benefit/cost ration of 1.4, work began in 1960. In 1970, the annual capital cost was 60,780 and operations/maintenance costs were 10,402, or a total annual project cost of $71, 182. High and low values of annual benefits from agricultural income, water supply, recreation, and non-agricultural flood damage were determined for 1970 and compared to annual project cost. The benefit/cost ratio obtained was between 0.25 and 0.58, considerably lower than the 1.4 estimate of the 1958. work plan. This unsatisfactory ratio for the project was due mainly to the failure of the project to encourage large scale cropping of bottomland area. Future projects should be planned with 1) a greater recognition of constraints on farm operator behavior which affect land use change, 2) conservative projection for land use changes in area where agriculture ids in overall decline, 3) increased use of sensitivity analysis to examine the consequences for project economic justification of alternative land use change projections.

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USGS1980

New evidence for the age of the Quantico Formation of Virginia

A new fossil locality within the Quantico Formation of the Virginia Piedmont in Dale City, Virginia, about 40 km south of Washington, D.C., has yielded crinoids and a cephalopod that re-establishes an age younger than Cambrian for this formation. On the basis of regional considerations and the work of investigators in the early 1900s, an Ordovician age for the Quantico seems likely. Also, the Dale City pluton is not intrusive into the Quantico but is unconformable beneath it. Hence, the 560-m.y. zircon age for the Dale City pluton is no longer inconsistent with the temporal and stratigraphic relationships established for the stratigraphic units in the area. © 1980 Geological Society of America.

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USGS1980

Neogene diatoms from Petersburg, Virginia

Sixty-two diatom taxa have been identified from a diatomaceous sandy clay that crops out near the outlet of Wilcox Lake, Petersburg. Virginia. These diatoms are mostly cosmopolitan marine forms, but some species suggest deposition in brackish water that had a freshwater inflow. The regional stratigraphy, as well as the pelecypods and foraminifers, indicates that the beds may have been laid down in a lagoonal or estuarine environment. The diatom assemblage suggests that the deposit is of early Pliocene age, although previous biostratigraphic studies have considered it to be latest Miocene.

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USGS1980

Maps showing coal resources of the Jewell Bridge Quadrangle, Buchanan and Tazewell counties, Virginia

Coal of low-volatile to high-volatile A bituminous rank is the principal developed mineral resource in the Jewell Ridge quadrangle. The coal beds in the Jewell Ridge quadrangle contain total estimated original resources of 1,519 million tons. Of this total, 108 million tons have been mined or lost in mining, leaving 1,411 million tons of remaining resources. Table 1 lists coal resource estimates for all coal beds in the quadrangle.

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USGS1980

Seismicity map of the State of Virginia

The earthquake data shown on this map and listed in table 1 are a list of earthquakes that were originally used in preparing the Seismic Risk Studies in the United States (Algermissen, 1969) which have been recompiled and updated through 1977. These data have been reexamined which resulted in some revisions of epicenters and intensities as well as assignment of intensities to earthquakes that previously had none assigned. Intensity values were updated from new and additional data sources that were not available at the time of original compilation. Some epicenters were relocated on the basis of new information. The data shown in table 1 are estimates of the most accurate epicenter, magnitude, and intensity of each earthquake, on the basis of historical and current information. Some of the aftershocks from large earthquakes are listed but are incomplete in many instances, especially for the ones that occurred before seismic instruments were in universal usage.

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USGS1980

Geophysical-geological analysis of Fairfax County, Virginia

Aeromagnetic, aeroradioactivity, and gravity surveys of Fairfax County, Virginia, are interpreted with the aid of existing geologic data and local geophysical measurements. Highly magnetic metasedimentary rocks of the Peters Creek Schist and Sykesville Formation produce most of the magnetic anomalies of Fairfax County. In contrast, the granitoid rocks of the Occoquan pluton are relatively non-magnetic and are characterized by broad magnetic and gravity lows. Linear magnetic highs without corresponding gravity anomalies, plus samples from a test well, indicate that Peters Creek Schist underlies the east side of the Triassic-Jurassic Culpeper basin. The continuation of the Piney Branch mafic-ultramafic complex beneath the basin is indicated by a gravity high. Basement lithology beneath the Coastal Plain sediments is interpreted by the following anomaly combinations: Sykesville Formation - magnetic high with no gravity expression; Chopawamsic Formation -magnetic and corresponding gravity high; Occoquan granitoid rocks -magnetic and corresponding gravity low. Analysis of a detailed gravity profile across a diabase body near Herndon indicates that the intrusive is a sill which is partly discordant with the sedimentary rocks of the Culpeper basin. The limbs of the horseshoe-shaped exposure dip gently toward the center; the west limb, 500 m thick, dips 15° east and the east limb, 250 m thick, dips west 3° or less. A second gravity profile across a similar diabase body near Centreville suggests that part of its western limb consists of a narrow dike-like body projecting upwards from a 200 m-thick buried sill. Both of these bodies apparently have a spoon-shaped structure with a discordant northern edge which was probably controlled by faulting. Similarities between these intrusives apply also to the small Boyds diabase in Maryland. The three diabase bodies are aligned, have similar magnetic expressions, and abut the edge of the Culpeper basin, suggesting that they were intruded under similar structural settings at about the same time. The northward decrease in size of these intrusives may be a consequence of the inward-dipping shape and a greater degree of uplift and deeper erosion to the north. By this reasoning, the Boyds body represents only the basal remnant of a largely eroded structure with the Centreville body preserving more of the original form. A ground magnetometer survey and an aeroradioactivity survey indicate the presence of additional zones in the thermal metamorphic aureole in the sedimentary rocks around the large diabase bodies. A 150-300-m-wide inner magnetite-rich zone above and below the Herndon sill is inferred from anomalies on a detailed ground magnetic profile. Aeroradioactivity data show a rim of high values outside the geologically mapped aureole of both the Herndon and Centreville bodies. This suggests a subtle outer zone slightly enriched in thermally expelled radio-elements. Deep resistivity soundings in the Culpeper basin indicate that the sedimentary rocks may reach a thickness of about 3600 feet (1100 m) at the western edge of the county.

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USGS1980

Revised nomenclature and stratigraphic relationships of the Fredericksburg Complex and Quantico Formation of the Virginia Piedmont

The Fredericksburg Complex, in part a migmatitic terrane in northeast Virginia, is subdivided on the basis of lithology, as well as aeromagnetic and aeroradiometric data, into two metamorphic suites. These suites are separated by the northeast-trending Spotsylvania lineament, a rectilinear geophysical feature that is probably the trace of an old fault zone. East of the lineament, the Po River Metamorphic Suite, of Proterozoic Z and (or) early Paleozoic age, consists dominantly of biotite gneiss, generally augen gneiss, and lesser amounts of hornblende gneiss and mica schist. West of the Spotsylvania lineament is the Ta River Metamorphic Suite, composed mostly of amphibolite and amphibole gneiss. However, to the southwest, along its strike belt, the Ta River contains abundant biotite gneiss and mica schist. Both the Ta River and Po River contain abundant foliated granitoid and pegmatoid bodies as concordant tabular masses and as crosscutting dikes; these rocks are considered part of the Ta River and Po River Metamorphic Suites. The amphibolitic Holly Corner Gneiss is interpreted to be a western allochthonous equivalent of the Ta River. Both the Ta River and Holly Corner are considered to be coeval, eastern, distal facies of the Lower Cambrian(?) Chopawamsic Formation. The Paleozoic Falls Run Granite Gneiss intrudes the Ta River Metamorphic Suite and the Holly Corner Gneiss; locally the Falls Run is interpreted to have been transported westward with the Holly Corner after intrusion. The Quantico Formation, in the core of the Quantico-Columbia synclinorium, rests with angular unconformity along its northwest and southeast limbs, respectively, on the Chopawamsic Formation and the Ta River Metamorphic Suite. The Quantico Formation is assigned the same Late Ordovician age and similar stratigraphic position as the Arvonia Slate of the Arvonia syncline. The youngest rocks of the area are the granitoid and pegmatoid bodies of the Falmouth Intrusive Suite. They consist of several generations of chiefly dikes and sills that are intrusive into the Fredericksburg Complex and into the Quantico Formation. Granitoid rocks also form small plutons. The Falmouth is isotopically dated as Carboniferous in age. Some of the metavolcanic rocks of the Evington Group and part of the amphibolite gneiss and amphibolite of the Hatcher Complex, named by W. B. Brown in 1969, are probably coeval with the Chopawamsic Formation and hence equivalents of the Ta River Metamorphic Suite and the Holly Corner Gneiss. The biotitic gneiss and granitoid rocks east of the Spotsylvania lineament in the Dillwyn area are considered to be coeval with the Po River Metamorphic Suite.

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USGS1980

Water resources data for Virginia, water year 1979

Water resources data for the 1979 water year for Virginia consist of records of stage, discharge, and water quality of streams; stage, contents, and water quality of lakes and reservoirs; and water levels and water quality of ground-water wells. This volume contains records for water discharge at 200 gaging stations; stage only at 1 gaging station; stage and contents at 9 lakes and reservoirs; water quality at 54 gaging stations and 38 wells; and water levels at 62 observation wells. Also included are data for 64 crest-stage partial-record stations. Locations of these sites are shown on figures 3 and 4. Additional water data were collected at various sites not involved in the systematic data-collection program. Discharge measurements and water-quality analyses were made at 97 coal-monitoring partial-record stations. Miscellaneous data were collected at 220 measuring sites and 64 water-quality sampling sites. These data represent that part of the National Water Data System collected by the U.S. Geological Survey and cooperating State and Federal agencies in Virginia.

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USGS1979

Similarities between the thick-skinned Blue Ridge anticlinorium and the thin-skinned Powell Valley anticline

The Blue Ridge anticlinorium in northern Virginia is a part of an integrated deformational system spanning the area from the Piedmont to the Appalachian Plateaus. Deformation intensity within the system decreases from east to west. Differences of opinion have emerged concerning the central Appalachians as to whether the basement rocks exposed in the core of the Blue Ridge anticlinorium are rooted or are allochthonous. Available surface and subsurface stratigraphic and structural data suggest that the anticlinorium may be a rootless thick-skinned analogue to the rootless thin-skinned Powell Valley anticline in the Valley and Ridge. Both structures were produced during the Alleghenian orogeny by similar deformational processes. The form of the Powell Valley anticline is attributed to duplication of about 4,575 m (15,000 ft) of sedimentary rock during approximately 16 km (10 mi) of northwest movement above a subhorizontal décollement. Similarly, the form of the Blue Ridge anticlinorium is attributed to duplication of about 9,150 m (30,000 ft) of igneous, metamorphic, and sedimentary rock during a minimum of 59 km (37 mi) of northwest movement above an eastward continuation of a subhorizontal décollement within Cambrian sedimentary rocks beneath the Valley and Ridge. Thus, in northern Virginia there is a mixing of structural styles: the thick-skinned rootless Blue Ridge anticlinorium sits above a thin-skinned detachment. This relationship implies that thin- and thick-skinned styles are simply end members of a complex deformational process that includes a transition zone, where characteristics of both styles commingle. © 1979 Geological Society of America.

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USGS1979

National Center tour guide

On behalf of each employee at the Geological Survey's National Center, I [H. William Menard, Director] extend a warm welcome to you during our Centennial Year. We hope that your visit to our headquarters will be a pleasant and rewarding experience. Our scientific research is directed towards helping to solve some of the critical environmental and natural resource problems that face our Nation today. We want you to see some aspects of this work, and we hope you will visit us again. As part of the Federal Government, we are deeply committed to the concept of public service. We are proud to serve you.

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USGS1979

Maps showing coal resources of the Honaker Quadrangle, Russell, Tazewell, and Buchanan counties, Virginia

The Honaker quadrangle lies in two physiographic provinces. The northern half of the quadrangle is part of the Appalachian Plateaus province, where the coal-bearing formations of Pennsylvanian age are nearly flat lying or very gently dipping. Diagonally extending east-northeastward across the middle of the quadrangle are several belts of faulted, overturned, and steeply dipping rocks of Mississippian and Pennsylvanian age which are in the fault system that separates the Appalachian Plateaus from the Valley and Ridge provinces. Several belts of Pennsylvanian rocks in this area contain coal beds that are exposed at the surface. South of the faulted and overturned belts of Mississippian and Pennsylvanian rocks is an area of older faulted and folded noncoal-bearing rock formations, which are also part of the Appalachian Valley and Ridge province and which form much of the southern half of the Honaker quadrangle.

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USGS1978

Flood-plain delineation for Horsepen Run, Sugarland Run, Nichols Run, Pond Branch, Clarks Branch, and Mine Run Branch basins, Fairfax County, Virginia

Water-surface profiles of the 25-year and 100-year floods and maps on which the 25-, 50-, and 100-year flood boundaries are delineated for streams in the Horsepen Run, Sugarland Run, Nichols Run, and Pond Branch basins are presented in this report. The techniques used in the computation of the flood profiles and delineation of flood boundaries are presented, and specific hydraulic problems encountered within the study area are also included.

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