Filters: Tags: Alluvial (X)8 results (258ms)
Geologic context, age constraints, and sedimentology of a Pleistocene volcaniclastic succession near Mount Spurr volcano, south-central Alaska
A physiographically prominent, approximately 40 square km plateau lies roughly 20 km east of Mount Spurr volcano, northwestern Cook Inlet region, Alaska, and comprises the preserved remnant of a volcaniclastic succession, designated in this study as map unit Qvc. Although this readily mappable package of volcaniclastic rocks has been recognized in numerous studies during the past five decades, uncertainties regarding its age and origin have persisted. We describe the general characteristics of the volcaniclastic plateau, provide new age constraints for deposits, present lithofacies descriptions and interpretations of the volcaniclastic strata, and synthesize our observations and lithofacies analysis to propose an...
New 1:24,000-scale geologic mapping in the Storm King Mountain7.5' quadrangle, in support of the USGS Western Colorado I-70Corridor Cooperative Geologic Mapping Project, provides new dataon the structure on the south margin of the White River upliftand the Grand Hogback and on the nature, history, anddistribution of surficial geologic units.Rocks ranging from Holocene to Proterozoic in age are shown onthe map. The Canyon Creek Conglomerate, a unit presently knownto only occur in this quadrangle, is interpreted to have beendeposited in a very steep sided local basin formed bydissolution of Pennsylvanian evaporite late in Tertiary time.At the top of the Late Cretaceous Williams Fork Formation is aunit of sandstone,...
Geologic map of the Dalton Highway (Atigun Gorge to Slope Mountain) area, southern Arctic Foothills, Alaska
This report provides detailed mapping (1:63,360-scale) in the Dalton Highway area, from Atigun Gorge to Slope Mountain, in the west-central Philip Smith Mountains quadrangle. The map area extends from the northern flank of the Endicott Mountains into the Arctic Foothills province.
Water-level data, selected water-quality data, and the potentiometric dataset for the Mississippi River Valley alluvial aquifer in eastern Arkansas, spring 2014
The alluvial aquifer of the Mississippi embayment lies within a syncline plunging south towards the Gulf of Mexico with the axis of the syncline roughly following the Mississippi River (Cushing and others, 1964, Hart and others, 2008). The trough of the syncline is comprised of alluvial and terrace deposits of Quaternary age (Ackerman, 1996). A potentiometric-surface map of the Mississippi River Valley alluvial aquifer represents the altitude at which water would stand in tightly cased wells completed at any location within the study area (Schrader, 2015). Using the altitude of water levels measured in the study area, the potentiometric-surface map depicts points of equal altitude with contours denoting a given...
Surficial geology of the Dalton Highway (Itkillik-Sagavanirktok rivers) area, southern Arctic foothills, Alaska
This report provides detailed (1:63,360-scale) surficial-geologic mapping in the Dalton Highway area, from the Sagavanirktok to the Itkillik Rivers, in the west-central Philip Smith Mountains quadrangle. The map area extends from the northern flank of the Endicott Mountains into the Arctic Foothills province.
The Alaska Division of Geological & Geophysical Surveys (DGGS), in partnership with the U.S. National Cooperative Geologic Mapping Program, mapped approximately 450 mi2 of the Talkeetna Mountains region of central Alaska at 1:50,000 scale over the course of six weeks in 2014. This area contains significant exposures of Late Triassic mafic volcanics and gabbro sills that have been the focus of region-wide exploration for the Strategic and Critical platinum-group elements (PGEs). The area also exposes numerous inactive and possibly active faults which project through the area of proposed hydropower development. The resulting geologic map offers an improved understanding of the geology, structural history, and mineral...
This 1:50,000 scale geologic map describes the distribution of unconsolidated deposits, identifies local geologic hazards, and provides information about the depositional environment and basic engineering properties of common surficial-geologic materials in and around Shaktoolik, Alaska. Map units are the result of combined field observations and aerial imagery interpretation. A suite of local ground observations were collected over a two-week period in July 2011 by a helicopter-supported team of DGGS geologists and collaborators. Field investigations included soil test pits, sample collection, soil and rock description, oblique aerial photography, and documentation of landscape morphology.
Data release of OSL, 14C, and U-series age data supporting geologic mapping along the South Platte River corridor in northeastern Colorado
In conjunction with geologic mapping of four 7.5′ quadrangles along the South Platte River corridor in northeastern Colorado (Masters, Orchard, Weldona, and Fort Morgan), geochronology samples were collected and analyzed using optically stimulated luminescence (OSL), radiocarbon (14C), or U-series methods to provide age control for mapping units. This section of river corridor is largely covered by surficial deposits that formed from alluvial, eolian, and hillslope processes operating in concert with environmental changes from the Pleistocene to the present. The South Platte River originates high in the Colorado Rocky Mountains and recurrent glaciation of basin headwaters has affected river discharge and sediment...