USA

Kennesaw State University, Kennesaw, Georgia, USA

Montana Weed Control Association - Online PDF document - Heritage Inn, Great Falls, Montana, USA

Carbondale, Colorado, USA

New data on Ru/Ir abundance ratios are presented for nonmarine (Hell Creek, Montana; Frenchman River, Saskatchewan) and marine Cretaceous-Tertiary boundary sites (Brazos River, Texas; Beloc, Haiti; DSDP 577 and DSDP 596). The Ru/Ir ratio varies from 0.5 to 1 within 4000 km of Chicxulub and increases to 2-3 at paleodistances (65 Ma) of up to 12,000 km from the impact site. For CI chondrites, Ru/Ir = 1.5.

High-precision uranium-thorium mass spectrometric chronology and 18O-13C isotopic analysis of speleothem calcite from Cold Water Cave in northeast Iowa have been used to chart mid-Holocene climate change. Significant shifts in d18O and d13C isotopic values coincide with well-documented Holocene vegetation changes. Temperature estimates based on 18O/16O ratios suggest that the climate warmed rapidly by about 3?C at 5900 years before present and then cooled by 4?C at 3600 years before present.

The Astoria submarine fan, located off the coast of Washington and Oregon, has grown throughout the Pleistocene from continental input delivered by the Columbia River drainage system. Enormous floods from the sudden release of glacial lake water occurred periodically during the Pleistocene, carrying vast amounts of sediment to the Pacific Ocean. DSDP site 174, located on the southern distal edge of the Astoria Fan, is composed of 879 m of terrigenous sediments.

Two marshes near Muscotah and Arrington, Atchison County, northeastern Kansas, yielded a pollen sequence covering the last 25,000 yrs of vegetation development. The earliest pollen spectra are comparable with surface pollen spectra from southern Saskatchewan and southeastern Manitoba and might indicate a rather open vegetation but with some pine, spruce, and birch as the most important tree species, with local stands of alder and willow. This type of vegetation changed about 23,000 yrs ago to a spruce forest, which prevailed in the region until at least 15,000 yrs ago.

Fluid pressure interpreted from uniaxial consolidation tests equals 80% of the overburden (total) stress in Pleistocene mudstones at Ocean Drilling Program (ODP) Site 1073 of the US mid-Atlantic continental slope, offshore New Jersey. The fluid overpressure decreases effective vertical stress and preserves void ratio (e) greater than 0.8 in Pleistocene sediments. Overpressure in Oligocene-Miocene sediments is lower even though e is high.

Native Cu occurs in amygdules, fractures and groundmass of tholeiites from Ocean Drilling Program Site 642 on the V?ring Plateau. Similar occurrences have been reported in other tholeiites of the early Tertiary North Atlantic Volcanic Province drilled at Deep Sea Drilling Project Sites 342 on the V?ring Plateau and 553 on the Rockall Plateau.

Massive discharges of freshwater from the glacial lake Missoula to the northeast Pacific Ocean are thought to have sculpted the Channeled Scablands of eastern Washington and debouched via the Columbia River near 46?N. The dynamics and timing of these events and their impact on northeast Pacific circulation remain uncertain. Here we date marine records of anomalous freshwater inputs to the ocean based on freshwater diatoms, oxygen isotopes in foraminifera, and radiocarbon data.