USGS Geoscience Data Catalog
Additional USGS Geoscience data can be found by geographic location or by publication series.
U.S. Geological Survey, and Reheis, Marith, 1999, Extent of Pleistocene Lakes in the Western Great Basin: U.S. Geological Survey Miscellaneous Field Studies Map MF-2323, U.S. Geological Survey, Denver, CO.Online Links:
This is a vector data set. It contains the following vector data types (SDTS terminology):
The map projection used is Lambert Conformal Conic.
Planar coordinates are encoded using Coordinate pair
Abscissae (x-coordinates) are specified to the nearest 130.0
Ordinates (y-coordinates) are specified to the nearest 130.0
Planar coordinates are specified in meters
The horizontal datum used is North American Datum of 1927.
The ellipsoid used is Clarke 1866.
The semi-major axis of the ellipsoid used is 6378206.4.
The flattening of the ellipsoid used is 1/294.98.
Production of this map was funded by a Gilbert Fellowship and by the Global Change and Climate History Program.
303-236-1270 (voice)
303-236-5349 (FAX)
mreheis@usgs.gov
The purpose of this map is to show the differences between the extents of late Pleistocene pluvial lakes and older, larger lakes caused by much higher effective moisture during past glacial-pluvial episodes.
U.S. Geological Survey, unknown, 1:250,000-scale Digital Elevation Model(DEM).
U.S. Geological Survey, unknown, 1:2,000,000-scale boundary and hydrology Digital Line Graphs.
Attributes within this dataset consist of the names of the lakes only, or flags (0|1) for presence/absence of a lake within a particular polygon. The attribute tables were checked for completeness (i.e. no empty fields), consistency (each "flag" field contains a 0 or 1 only), and for spelling of geographic feature names.
The lake shoreline locations are delineated using contour lines derived from DEM source data with 3 arc-second (nominally 90 meters) grid cell resolution. Horizontal accuracy of DEM data is dependent upon the horizontal spacing of the elevation matrix. Within a standard DEM, most terrain features are generalized by being reduced to grid nodes spaced at regular intersections in the horizontal plane. This generalization reduces the ability to recover positions of specific features less than the internal spacing during testing and results in a de facto filtering or smoothing of the surface during gridding. The broad DMA production objective for a 1-degree DTED-1 is to satisfy an absolute horizontal accuracy (feature to datum) of 130 m, circular error at 90-percent probability. The relative horizontal accuracy (feature to feature on the surface of the elevation model), although not specified, will in many cases conform to the actual hypsographic features with higher integrity than indicated by the absolute accuracy.
The lake elevations were derived from DEM source data with 3 arc-second (nominally 90 meters) grid cell resolution. Vertical accuracy of DEM data is dependent upon the spatial resolution (horizontal grid spacing), quality of the source data, collection and processing procedures, and digitizing systems. Within a standard DEM, most terrain features are generalized by being reduced to grid nodes spaced at regular intersections in the horizontal plane. This generalization reduces the ability to recover positions of specific features less than the internal spacing during testing and results in a de facto filtering or smoothing of the surface during gridding. The broad DMA production objective for a 1-degree DTED-1 is to satisfy an absolute vertical accuracy (feature to mean sea level) of + or - 30 m linear error at 90-percent probability. The relative vertical accuracy (feature to feature on the surface of the elevation model), although not specified, will in many cases conform to the actual hypsographic features with higher integrity than indicated by the absolute accuracy.
Late Pleistocene lake areas are shown for all pluvial lakes within the map area that extend into Nevada or are part of the Lahontan drainage basin. However, larger, pre-late Pleistocene areas are shown only for lake basins which have been visited in the field by the author. The extent of older pluvial lakes in unvisited lake basins is unknown.
Lake areas (late Pleistocene and maximum) are based on shoreline altitudes measured at the field localities shown on map and described in detail in Reheis and Morrison (1997) and Reheis and others (in press). Lake areas were plotted using contour lines of lake-surface altitudes generated from DEMs. Inferred additional area of lakes is approximately delineated based on the author's judgement and is least accurate. Map elements were visually checked for overshoots, undershoots, duplicate features, and other errors.
Are there legal restrictions on access or use of the data?
- Access_Constraints: none
- Use_Constraints: none
1-888-ASK-USGS (voice)
MF-2323
none
Available as one printed sheet - order from USGS at the address listed above or see <http://mapping.usgs.gov/esic/order_forms/map_order.html> for more ordering information.
| Data format: | Arc/Info Export (.e00), ArcView shapefile (.shp) |
|---|---|
| Network links: |
<http://greenwood.cr.usgs.gov/pub/mf-maps/mf-2323/> |
303-236-4610 (voice)
dsistine@usgs.gov
U.S. Department of the Interior |
U.S. Geological Survey
URL: http://geo-nsdi.er.usgs.gov/metadata/map-mf/2323/metadata.faq.html
Page Contact Information: Peter Schweitzer
Page Last Modified: Friday, 19-Oct-2007 13:35:13 EDT
