Publications

No abstract available.

Aeromagnetic surveys, spaced ≤5 km, over widely separated areas of the largely ice- and sea-covered West Antarctic rift system, reveal similar patterns of 100- to 1700-nT, shallow-source magnetic anomalies interpreted as evidence of extensive late Cenozoic volcanism. We use the aeromagnetic data to extend the volcanic rift interpretation over West Antarctica starting with anomalies over...

Rivers and streams throughout Pennsylvania (fig. 1) experienced major flooding during January 1996. Flood stages (water-surface heights) and discharges (flows) in many of the Commonwealth's waterways were measured by the U.S. Geological Survey (USGS) and approached or exceeded record levels established during previous floods. Setting the stage for the flooding was an unusually cold...

We studied the impacts of camping on soil and vegetation at Delaware Water Gap national Recreation Area. We assessed the magnitude of impact on campsites that varied in amount of use and in topographic position. We also evaluated change over a 5-yr period on long-established, recently opened, and recently closed campsites, as well as on plots subjected to experimental trampling. Campsite...

Suspended-sediment concentration and discharge data were collected at 7 daily record stations and 70 partial-record stations during 1952- 84. Median suspended-sediment concentrations ranged from 24 to 61 milligrams per liter at daily record stations; concentrations ranged from 6 to 539 milligrams per liter at partial-record stations. Most suspended sediment transported in Indiana streams...

We examined diets of smolts of 224 “wild” and 150 hatchery Atlantic salmon Salmo salar; wild smolts had been released as fry from the hatchery 2 years before collection, whereas hatchery fish were released as smolts from the hatchery 3–15 d before. Smolts were collected from 1991 to 1993 at trapping facilities at dams in the Merrimack River during spring outmigration. About 50% of the...

We tracked 10 ultrasonically tagged shortnose sturgeons Acipenser brevirostrurn during spring in the Merrimack River to investigate spawning. Seven fish in 1989 and six fish in 1990 were tracked intensively to identify the timing and location of spawning and to characterize spawning habitat. In mid‐April 1989 and 1990, fish moved upstream to just below head of tide, concentrating in a 2...

A comparison of 40Ar/39Ar age spectra of whole-rock mudstone and slate samples from the Ordovician Martinsburg Formation at Lehigh Gap, Pennsylvania and stratigraphic and thermal constraints support Alleghanian age for regional slaty cleavage and a late Acadian age for diagenesis in these rocks. Age spectra from mud-stones have a sigmodal shape, with slopes that climb steeply from...

No abstract available.

The National Biological Service's Leetown Science Center is investigating how human impacts on watershed, riparian, and in-stream habitats affect fish communities. The research will provide the basis for a Ridge and Valley model that will allow resource managers to accurately predict and effectively mitigate human impacts on water quality. The study takes place in the Opequon Creek...

Aluminum (Al) is the third most common mineral and the most common metal in Earth’s crust, accounting for approximately 8.1% of the crust by weight. Thus, it cannot be considered a contaminant in the usual sense of the word. However, despite its near omnipresence throughout the world, Al has been of major concern as a primary limiting factor to cultivated plants for several decades. In...

Kirtland's Warbler Dendroica kirtlandii breeds in young jack pine Pinus banksiana forests on sandy soils in Michigan's lower peninsula, where there were 502 censused singing males in 1951 and 167 in 1974 and 1987. An ongoing control programme for the Brown-headed Cowbird Molothrus ater, a nest parasite, resulted in immediate and continued improvement in warbler reproductive success which...