Publications
Filter Total Items: 834
40Ar/39Ar dating of Silurian and late Devonian cleavages in lower greenschist-facies rocks in the Westminster terrane, Maryland, USA
40Ar/39Ar dating of muscovite, biotite, and K-feldspar combined with microstructural analysis of lower greenschist-facies, polymetamorphic, phyllitic rocks, and marbles were successfully used to decipher the thermal and tectonic histories of the Westminster and adjacent terranes in western Maryland. The presence of unreset detrital muscovite in some samples demonstrates that temperatures in these
Authors
R. P. Wintsch, Michael J. Kunk, Brian Mulvey, C. Scott Southworth
The biostratigraphic importance of conchostracans in the continental Triassic of the northern hemisphere
Conchostracans or clam shrimp (order Conchostraca Sars) are arthropods with a carapace consisting of two chitinous lateral valves. Triassic conchostracans range in size from 2 to 12.5 mm long and are common in deposits that formed in fresh water lakes, isolated ponds and brackish areas. Their dessication- and freeze-resistant eggs can be dispersed by wind over long distances. Therefore many concho
Authors
H. W. Kozur, Robert E. Weems
Meteoric 10Be in soil profiles - A global meta-analysis
In order to assess current understanding of meteoric 10Be dynamics and distribution in terrestrial soils, we assembled a database of all published meteoric 10Be soil depth profiles, including 104 profiles from 27 studies in globally diverse locations, collectively containing 679 individual measurements. This allows for the systematic comparison of meteoric 10Be concentration to other soil characte
Authors
Joseph A. Graly, Paul R. Bierman, Lucas J. Reusser, Milan J. Pavich
A model for Iapetan rifting of Laurentia based on Neoproterozoic dikes and related rocks
Geologic evidence of the Neoproterozoic rifting of Laurentia during breakup of Rodinia is recorded in basement massifs of the cratonic margin by dike swarms, volcanic and plutonic rocks, and rift-related clastic sedimentary sequences. The spatial and temporal distribution of these geologic features varies both within and between the massifs but preserves evidence concerning the timing and nature o
Authors
William C. Burton, Scott Southworth
Petrography, mineralogy, and geochemistry of deep gravelly sands in the Eyreville B core, Chesapeake Bay impact structure
The ICDP–USGS Eyreville drill cores in the Chesapeake Bay impact structure reached a total depth of 1766 m and comprise (from the bottom upwards) basement-derived schists and granites/pegmatites, impact breccias, mostly poorly lithified gravelly sand and crystalline blocks, a granitic slab, sedimentary breccias, and postimpact sediments. The gravelly sand and crystalline block section forms an app
Authors
Katerina Bartosova, Susanne Gier, J. Wright Horton, Christian Koeberl, Dieter Mader, Henning Dypvik
Geologic characteristics and movement of the Meadow Creek landslide, part of the Coal Hill landslide complex, western Kane County, Utah
The Meadow Creek landslide, part of the Coal Hill landslide complex in western Kane County, Utah, is about 1.7 miles (2.7 km) wide and 1.3 miles (2.1 km) long and contains six smaller historical slides. The upper part of the Meadow Creek landslide is gently sloping and consists of displaced and back-rotated blocks of Cretaceous Dakota and Cedar Mountain Formations that form northeast- to locally
Authors
Francis X. Ashland, Greg N. McDonald
Tectonics of the Maryland Piedmont along the Potomac River; insight since 1960 and potential transfer to the Pennsylvania Piedmont
This is a summary of a half century of research in the Mary land Piedmont and how it may or may not have implications for the Piedmont of Pennsylvania. Much of the field mapping and all of the isotopic analyses of rocks and minerals of the Maryland Piedmont have been conducted since the 1960 Field Conference of Pennsylvania Geologists “Some tectonic and structural problems of the Appalachian Piedm
Authors
C. Scott Southworth
Conodont biostratigraphy of a more complete Reef Trail Member section near the type section, latest Guadalupian Series type region
The original type section of the Reef Trail Member (uppermost part of the Bell Canyon Formation) is called the Park Boundary Section, and is less than satisfactory in several aspects. We propose a new reference section designated Reef Trail Reference section 1 (RTR1) on the same hill as the original type section. Section RTR1 compensates for some of the Park Boundary Section’s shortcomings, includ
Authors
Bruce R. Wardlaw, L.L. Lambert, G.L. Bell, J.A. Fronimos, M.O. Yisa
Aviation response to a widely dispersed volcanic ash and gas cloud from the August 2008 eruption of Kasatochi, Alaska, USA
The extensive volcanic cloud from Kasatochi's 2008 eruption caused widespread disruptions to aviation operations along Pacific oceanic, Canadian, and U.S. air routes. Based on aviation hazard warnings issued by the National Oceanic and Atmospheric Administration, U.S. Geological Survey, the Federal Aviation Administration, and Meteorological Service of Canada, air carriers largely avoided the volc
Authors
Marianne Guffanti, David J. Schneider, Kristi L. Wallace, Tony Hall, Dov R. Bensimon, Leonard J. Salinas
Pliocene climate
The Pliocene Epoch, 5.3 Ma to 1.8 Ma, was a time when paleoclimate conditions ranged from very warm, equable climates (on a global scale), rhythmically varying every 40,000 years, to high-amplitude glacial-interglacial cycles that led to the “Ice Ages” of the Pleistocene. Evidence for paleoclimate conditions comes from fossils, geochemical data, and the integration of these data with sophisticated
Authors
Harry J. Dowsett, R. P. Caballero-Gill
Rift-related volcanism and karst geohydrology of the southern Ozark Dome
This field trip examines the geology and geohydrology of a dissected part of the Salem Plateau in the Ozark Plateaus province of south-central Missouri. Rocks exposed in this area include karstified, flat-lying, lower Paleozoic carbonate platform rocks deposited on Mesoproterozoic basement. The latter is exposed as an uplift located about 40 mi southwest of the St. Francois Mountains and form the
Authors
Richard W. Harrison, David J. Weary, Randall C. Orndorff, John E. Repetski, Herbert A. Pierce, Gary R. Lowell
Some notes on the geology of Cave Mountain Cave, Pendleton County, West Virginia
No abstract available.
Authors
C.S. Swezey, F.T. Dulong