Publications

Recent mapping efforts and hydrocarbon exploration in the South Park Basin have brought to light the magnitude in complexity of a structural basin already recognized for its unique sedimentary and tectonic setting. This fi eld trip to one of Colorado’s scenic gems will examine how Paleozoic, Mesozoic, and Cenozoic strata record the tectonic signatures of at least three orogenic episodes...

A continuous window into the fluvial-lacustrine basin-fill succession of the Uinta Basin is exposed along a 48-mile (77-kilometer) transect up the modern Green River from Three Fords to Sand Wash in Desolation Canyon, Utah. In ascending order the stratigraphic units are: 1) Flagstaff Limestone, 2) lower Wasatch member of the Wasatch Formation, 3) middle Wasatch member of the Wasatch...

The stable isotopes of oxygen and hydrogen, measured in a variety of archives, are widely used proxies in Quaternary Science. Understanding the processes that control δ18O change have long been a focus of research (e.g. Shackleton and Opdyke, 1973; Talbot, 1990 ; Leng, 2006). Both the dynamics of water isotope cycling and the appropriate interpretation of geological water-isotope proxy...

The San Luis Basin encompasses the largest structural and hydrologic basin of the Rio Grande rift. On this field trip, we will examine the timing of transition of the San Luis Basin from hydrologically closed, aggrading subbasins to a continuous fluvial system that eroded the basin, formed the Rio Grande gorge, and ultimately, integrated the Rio Grande from Colorado to the Gulf of Mexico...

Sediment cores from Great Salt Lake (GSL) provide the basis for reconstructing changes in lakes, vegetation, and climate for the last ~ 40 cal ka. Initially, the coring site was covered by a shallow saline lake and surrounded by Artemisia steppe or steppe-tundra under a cold and dry climate. As Lake Bonneville began to rise (from ~ 30 to 28 cal ka), Pinus and subalpine conifer pollen...

Desert wetlands are common features in arid environments and include a variety of hydrologic facies, including seeps, springs, marshes, wet meadows, ponds, and spring pools. Wet ground conditions and dense stands of vegetation in these settings combine to trap eolian, alluvial, and fluvial sediments that accumulate over time. The resulting deposits are collectively called ground-water...

Significant changes in wildfire occurrence, extent, and severity in areas such as western North America and Indonesia in 2015 have made the issue of fire increasingly salient in both the public and scientific spheres. Biomass combustion rapidly transforms land cover, smoke pours into the atmosphere, radiative heat from fires initiates dramatic pyrocumulus clouds, and the repeated...

This field-trip guide outlines the glacial history of the upper Arkansas River valley, Colorado, and builds on a previous GSA field trip to the area in 2010. The following will be presented: (1) new cosmogenic 10Be exposure ages of moraine boulders from the Pinedale and Bull Lake glaciations (Marine Isotope Stages 2 and 6, respectively) located adjacent to the Twin Lakes Reservoir, (2)...

Numerous geochemical and geophysical studies have been conducted at Yellowstone National Park to better understand the hydrogeologic processes supporting the thermal features of the Park. This report provides the first 87Sr/86Sr and 234U/238U data for thermal water from the Upper Geyser Basin (UGB) intended to evaluate whether heavy radiogenic isotopes might provide insight to sources of

The Upton Chamber in Massachusetts, an earth-covered stone structure 3.4 meters (m) in diameter, with a corbelled stone dome, and a 4.3 m long entrance passageway, is studied with the aim of determining whether optically stimulated luminescence (OSL) dating methods can be used to establish the approximate construction date of the entranceway. Three samples, taken from soil behind the...

We present ∼1300 new isotopic measurements (δ18O and δ2H) from a network of snowpack sites in the Rocky Mountains that have been sampled since 1993. The network includes 177 locations where depth-integrated snow samples are collected each spring near peak accumulation. At 57 of these locations snowpack samples were obtained for 10–21 years and their isotopic measurements provide...

Scientists from the U.S. Geological Survey (USGS) are finding evidence of a much wetter past in the deserts of the American Southwest using a most unlikely source—wetlands. Wetlands form in arid environments where water tables approach or breach the ground surface. Often thought of as stagnant and unchanging, new evidence suggests that springs and wetlands responded dynamically to past...