Conference Papers

No abstract available.

The USGS is producing digital elevation models (DEM) and topographic maps of Mars at scales of 1:250,000 to 1:1,000,000. The initial source material will be Viking Orbiter images, with a later transition to Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) when stereo coverage from that source is available for topographic mapping. The digital terrain models and topographic maps produced by this

No abstract available.

No abstract available.

A substantial number of invasive grasses, forbs and woody plants have invaded temperate grasslands in North America. Among the invading species are winter annuals, biennials, cool-season perennials, warm-season perennials, vines, shrubs, and trees. Many of these species have been deliberately introduced and widely planted; some are still used for range improvement, pastures, lawns, and as ornament

The U.S. Geological Survey began data-collection activities in the Eastern Iowa Basins study unit of the National Water-Quality Assessment Program in September 1995 with the purpose of determining the status and trends in water quality of water from the Wapsipinicon, Cedar, Iowa, and Skunk River basins. From March 1996 through September 1998, monthly surface-water samples were collected from 11 si

An important theme of our work is the synergistic use of a variety of geodetic, cartographic, and photogrammetric software packages. The USGS digital cartographic software system ISIS provides most of the processing capability needed for planimetric mapping tasks such as our revision of the global digital image mosaic of Mars (MDIM).  The geodetic control network on which this mosaic is based was

This paper presents the results to-date from a continuing investigation into the differences between total suspended solids (TSS) and suspended-sediment concentration (SSC) data and the ramifications of using each type of data to estimate sediment loads. It compares estimates of annual suspended-sediment loads that were made using regression equations developed from paired TSS and SSC data, to ann

Elevation models produced from Shuttle Radar Topography Mission (SRTM) data will be the most comprehensive, consistently processed, highest resolution topographic dataset ever produced for the Earth's land surface. Many applications that currently use elevation data will benefit from the increased availability of data with higher accuracy, quality, and resolution, especially in poorly mapped areas

A strategy for selecting Landsat 7 ETM+ imagery for development of a new generation national land cover database of the United States has been developed. This strategy is formulated to target Landsat 7 ETM+ scenes based on land cover and land use, vegetation phenology and image quality (cloudiness, haze). Criteria based on phenology and scene quality provide a national baseline for acquiring Lands

Secubelmis limpida n. sp., n. gen., is described from Montana, U.S.A. The monotypic genus resembles the lumbriculid genera Rhynchelmis and Tatriella in having atria in X, spermathecae in VIII, and semi-prosoporous male ducts. It differs from Tatriella in having paired atria and spermathecae, and from Rhynchelmis in having petiolate atria. The single prostate gland is unique within the Lumbriculida

Abstract not available