Estimating effects of limiting factors with regression quantiles
Brian S. Cade, J. W. Terrell, Richard L. Schroeder
1999, Ecology (80) 311-323
In a recent Concepts paper in Ecology, Thomson et al. emphasized that assumptions of conventional correlation and regression analyses fundamentally conflict with the ecological concept of limiting factors, and they called for new statistical procedures to address this problem. The analytical issue is that unmeasured factors may be the active...
Large-magnitude, late Holocene earthquakes on the Genoa fault, West-Central Nevada and Eastern California
A. R. Ramelli, J. W. Bell, C.M. DePolo, J. C. Yount
1999, Bulletin of the Seismological Society of America (89) 1458-1472
The Genoa fault, a principal normal fault of the transition zone between the Basin and Range Province and the northern Sierra Nevada, displays a large and conspicuous prehistoric scarp. Three trenches excavated across this scarp exposed two large-displacement, late Holocene events. Two of the trenches contained multiple layers of stratified...
Late Quaternary loess in northeastern Colorado: Part I - Age and paleoclimatic significance
D.R. Muhs, J. N. Aleinikoff, Thomas W. Stafford Jr., R. Kihl, J. Been, S. A. Mahan, S. Cowherd
1999, Geological Society of America Bulletin (111) 1861-1875
Loess in eastern Colorado covers an estimated 14 000 km2, and is the westernmost part of the North American midcontinent loess province. Stratigraphic studies indicate there were two periods of loess deposition in eastern Colorado during late Quaternary time. The first period spanned...
Dynamic 3D simulations of earthquakes on en echelon faults
R.A. Harris, S.M. Day
1999, Geophysical Research Letters (26) 2089-2092
One of the mysteries of earthquake mechanics is why earthquakes stop. This process determines the difference between small and devastating ruptures. One possibility is that fault geometry controls earthquake size. We test this hypothesis using a numerical algorithm that simulates spontaneous rupture propagation in a three-dimensional...
Environmental geology: Our professional public responsibility
L. C. Gerhard, L. L. Brady
1999, Environmental Geology (37) 1-8
Conflicts between different interest groups for use of natural resources is one area where state geological surveys can provide assistance. A state geological survey working within the scientific constraints of specific issues can remain objective in its presentations and maintain the faith of both the conflicting interest groups and the...
Analysis of earthquake recordings obtained from the Seafloor Earthquake Measurement System (SEMS) instruments deployed off the coast of southern California
D.M. Boore, C. E. Smith
1999, Bulletin of the Seismological Society of America (89) 260-274
For more than 20 years, a program has been underway to obtain records of earthquake shaking on the seafloor at sites offshore of southern California, near oil platforms. The primary goal of the program is to obtain data that can help determine if...
Stem demography and post-fire recruitment of a resprouting serotinous conifer
Jon E. Keeley, M.B. Keeley, W.J. Bond
1999, Journal of Vegetation Science (10) 69-76
The contribution of resprouts and seedling recruitment to post-fire regeneration of the South African fynbos conifer Widdringtonia nodiflora was compared eight months after wildfires in 1990. Stems on all trees were killed by fire but resprouting success was > 90 % at all but one site. A demographic study of burned skeletons...
The Puelche volcanic field: Extensive Pleistocene rhyolite lava flows in the Andes of central Chile
Wes Hildreth, J. Fierstein, E. Godoy, Robert E. Drake, B. Singer
1999, Revista Geologica de Chile (26) 275-309
A remote volcanic field in the rugged headwaters of the Río Puelche and Río Invernada (35.8°S) constitutes the largest cluster of Quaternary rhyolite lava flows yet identified in the Andean Southern Volcanic Zone. The Puelche Volcanic Field belongs to an intra-arc belt of silicic magmatic centers that extends, at least,...
Late Quaternary loess in northeastern Colorado: Part II - Pb isotopic evidence for the variability of loess sources
J. N. Aleinikoff, D.R. Muhs, R.R. Sauer, C.M. Fanning
1999, Geological Society of America Bulletin (111) 1876-1883
Loess in eastern Colorado covers an estimated 14 000 km2, and is the westernmost part of the North American midcontinent loess province. Stratigraphic studies indicate there were two periods of loess deposition in eastern Colorado during late Quaternary time. The first period spanned...
The insect trace fossil Tonganoxichnus from the middle Pennsylvanian of Indiana: Paleobiologic and paleoenvironmental implications
M. Gabriela Mángano, Conrad C. Labandeira, Erik P. Kvale, Luis A. Buatois
1999, Ichnos: An International Journal for Plant and Animal Traces (8) 165-175
The ichnogenus Tonganoxichnus, produced by one or more monuran insect taxa, is now recorded from the Middle Pennsylvanian Mansfield Formation of Indiana. Tonganoxichnus is a resting trace that has three important implications. First, it represents a recurrent behavioral pattern in Upper Carboniferous to Lower Permian marginal marine environments of North America. Second, it...
Seismic hazard map of North and Central America and the Caribbean
K. M. Shedlock
1999, Annals of Geophysics (42) 977-997
Minimization of the loss of life, property damage, and social and economic disruption due to earthquakes depends on reliable estimates of seismic hazard. National, state, and local government, decision makers, engineers, planners, emergency response organizations, builders, universities, and the general public require seismic hazard estimates for land use planning, improved...
Velocity reversals and sediment sorting in pools and riffles controlled by channel constrictions
D.M. Thompson, E.E. Wohl, R.D. Jarrett
1999, Geomorphology (27) 229-241
Keller [Keller, E.A., 1971. Areal sorting of bed-load material; the hypothesis of velocity reversal. Geological Society of America Bulletin 82, 753-756] hypothesized that at high flow, near-bed velocities in pools exceed velocities in riffles and create pool scour. Pools, however, typically have larger cross-sectional areas of flow at bankfull discharge....
Proposed nomenclature for samarskite-group minerals: new data on ishikawaite and calciosamarskite
S.L. Hanson, W.B. Simmons, A.U. Falster, E.E. Foord, F.E. Lichte
1999, Mineralogical Magazine (63) 27-36
The current definition of samarskite-group minerals suggests that ishikawaite is a uranium rich variety of samarskite whereas calciosamarskite is a calcium rich variety of samarskite. Because these minerals are chemically complex, usually completely metamict, and pervasively altered, their crystal chemistry and structure are poorly understood. Warner and Ewing (1993) proposed...
Health status and relative exposure of mule deer and white-tailed deer to soil contaminants at the rocky mountain arsenal
Terry E. Creekmore, Don Whittaker, Richard R. Roy, J. Christian Franson, Dan L. Baker
1999, Environmental Toxicology and Chemistry (18) 272-278
We evaluated the health of 18 radio-collared deer [13 mule deer (Odocoileus hemionus) and 5 white-tailed deer (O. virginianus)] from the Rocky Mountain Arsenal, near Denver, Colorado, USA, a Superfund site contaminated with a variety of materials, including organochlorine pesticides, metals, and nerve gas production by-products. Radio-collared deer were tracked...
Professional conduct of scientists during volcanic crises
IAVCEI Subcommittee for Crisis Protocols, Chris Newhall, Shigeo Aramaki, Franco Barberi, Russell Blong, Marta Calvache, Jean-Louis Cheminee, Raymundo Punongbayan, Claus Siebe, Tom Simkin, Stephen Sparks, Wimpy Tjetjep
1999, Bulletin of Volcanology (60) 323-334
Stress during volcanic crises is high, and any friction between scientists can distract seriously from both humanitarian and scientific effort. Friction can arise, for example, if team members do not share all of their data, if differences in scientific interpretation erupt into public controversy, or if one scientist begins work...
Deformation and quaternary faulting in southeast Missouri across the Commerce geophysical lineament
W. J. Stephenson, J. K. Odum, R. A. Williams, T. L. Pratt, R.W. Harrison, D. Hoffman
1999, Bulletin of the Seismological Society of America (89) 140-155
High-resolution seismic-reflection data acquired at three sites along the surface projection of the Commerce geophysical lineament in southeast Missouri reveal a complex history of post-Cretaceous faulting that has continued into the Quaternary. Near Qulin, Missouri, approximately 20 m of apparent vertical fault displacement has occurred in the Quaternary. Reflection data...
Measurement of velocities with an acoustic velocity meter, one side-looking and two upward-looking acoustic Doppler current profilers in the Chicago Sanitary and Ship Canal, Romeoville, Illinois
Kevin A. Oberg, James J. Duncker
1999, Proceedings of the IEEE Working Conference on Current Measurement 117
In 1998, a prototype 300 kHz, side-looking Acoustic Doppler Current Profiler (ADCP) was deployed in the Chicago Sanitary and Ship Canal (CSSC) at Romeoville, Illinois. Additionally, two upward-looking ADCP's were deployed in the same acoustic path as the side-looking ADCP and in the reach defined by the upstream and downstream...
Potential geologic hazards on the eastern Gulf of Cadiz slope (SW Spain)
J. Baraza, G. Ercilla, C.H. Nelson
1999, Marine Geology (155) 191-215
Geologic hazards resulting from sedimentary, oceanographic and tectonic processes affect more than one third of the offshore Gulf of Cadiz, and are identified by interpreting high-resolution seismic profiles and sonographs. Hazards of sedimentary origin include the occurrence of slope instability processes in the form of single or multiple slumps occupying...
Use of cosmogenic 35S for comparing ages of water from three alpine-subalpine basins in the Colorado Front Range
J.K. Sueker, J.T. Turk, R. L. Michel
1999, Geomorphology (27) 61-74
High-elevation basins in Colorado are a major source of water for the central and western United States; however, acidic deposition may affect the quality of this water. Water that is retained in a basin for a longer period of time may be less impacted by acidic deposition. Sulfur-35 (35S), a...
Paleoclimatic significance of δD and δ13C values in pinon pine needles from packrat middens spanning the last 40,000 years
Elise Pendall, Julio L. Betancourt, Steven W. Leavitt
1999, Palaeogeography, Palaeoclimatology, Palaeoecology (147) 53-72
We compared two approaches to interpreting δD of cellulose nitrate in piñon pine needles (Pinus edulis) preserved in packrat middens from central New Mexico, USA. One approach was based on linear regression between modern δD values and climate parameters, and the other on a deterministic isotope model, modified from Craig...
Root and shoot responses of Taxodium distichum seedlings subjected to saline flooding
K. W. Krauss, J. L. Chambers, J. A. Allen, B.P. Luse, A.S. DeBosier
1999, Environmental and Experimental Botany (41) 15-23
Variation among progeny of five half-sib family collections of baldcypress (Taxodium distichum) from three freshwater and two brackish-water seed sources subjected to saline flooding was evaluated Mini-rhizotrons (slant tubes) were used to monitor root elongation for a period of 99 days. Salinity level produced significant effects across all baldcypress half-sib...
Natural regeneration and growth of Taxodium distichum (L.) rich. In Lake Chicot, Louisiana after 44 years of flooding
B. D. Keeland, W.H. Conner
1999, Wetlands (19) 149-155
Lake Chicot, in south central Louisiana, USA, was created in 1943 by the impoundment of Chicot Bayou. Extensive establishment of woody seedlings occurred in the lake during a 1.5 year period, including the growing seasons of both 1986 and 1987, when the reservoir was drained for repair work on the...
Temporal and spatial variability of the sediment grain-size distribution on the Eel shelf: The flood layer of 1995
D.E. Drake
1999, Marine Geology (154) 169-182
Sediment grain-size characteristics observed on the Eel shelf have been analyzed using a wet-sieving technique that minimizes breakage of aggregates. At several sites on the 70-m isobath north of the river, where a 1995 flood layer attained a maximum thickness of about 9 cm, replicate box cores were collected on...
The search for a source rock for the giant Tar Sand triangle accumulation, southeastern Utah
J. E. Huntoon, P. L. Hansley, N. D. Naeser
1999, American Association of Petroleum Geologists Bulletin (83) 467-495
A large proportion (about 36%) of the worlds oil resource is contained in accumulations of heavy oil or tar. In these large deposits of degraded oil, the oil in place represents only a fraction of what was present at the time of accumulation. In many of these deposits, the source...
Stratigraphic framework and heavy minerals of the continental shelf of Onslow and Long Bays, North Carolina
Charles W. Hoffman, Andrew E. Grosz, John G. Nickerson
1999, Marine Georesources and Geotechnology (17) 173-184
One hundred fourteen vibracores from the Atlantic continental shelf offshore of southeastern North Carolina were opened, described, and processed over several contract years (years 6-9) of the Minerals Management Service-Association of American State Geologists Continental Margins program. Reports for years 9 and 10 of the program compiled the results of...
