Converse County Research Articles

Use of hare bone for the manufacture of a Clovis bead

A tubular bone bead dating to ~ 12,940 BP was recovered from a hearth-centered activity area at the La Prele Mammoth site in Converse County, Wyoming, USA. This is the oldest known bead from the Western Hemisphere. To determine the taxonomic origin of the bead, we extracted collagen for zooarchaeology by mass spectrometry (ZooMS). We also used micro-CT scanning for morphological analysis to determine likely skeletal elements used for its production. We conclude that the bead was made from a metapodial or proximal phalanx of a hare (Lepus sp.). This find represents the first secure evidence for the use of hares during the Clovis period. While the use of hare bone for the manufacture of beads was a common practice in western North America during the Holocene, its origins can now be traced back to at least the terminal Pleistocene.

Interlaboratory Comparison of 226Ra and 228Ra Activity Concentrations in Groundwater and Surface Water

226Ra and 228Ra are typically monitored for groundwater and surface water compliance at legacy U mining and milling sites. Groundwater monitoring results for combined Ra (226Ra + 228Ra) reported by the existing contract laboratory at a former U mine and mill Site (Converse County, WY, USA) have been highly variable and with increasing trends at the Site compliance and background wells since the method was changed in 2005. Sample reanalysis has indicated poor reproducibility and significant analytical error in 228Ra measurements. An interlaboratory comparison was conducted to evaluate the potential causes of the high variability and analytical error. Two different methods were used for 226Ra (M903.0 and M903.1) and 228Ra (M904.0 and Ra-05). 226Ra results were less variable compared to 228Ra, and 228Ra data from the existing laboratory were qualified as estimated with high bias due to detection of 228Ra in the field blank. Compliance with the 226Ra + 228Ra groundwater standard was either met or not met, depending on which laboratory conducted the analyses. Specific laboratory techniques, rather than the analytical method, are contributing to elevated 228Ra values being reported. It was recommended that samples whose 226Ra + 228Ra results exceed the Site standard in the future be reanalyzed by the existing laboratory with a sample split also being sent to an outside laboratory for confirmatory analysis.

Evaluation of a liquid carbaryl formulation to control burrow fleas following a die-off of black-tailed prairie dogs (Cynomys ludovicianus) caused by plague (Yersinia pestis) in Converse County, Wyoming.

Evaluation of a liquid carbaryl formulation to control burrow fleas following a die-off of black-tailed prairie dogs (Cynomys ludovicianus) caused by plague (Yersinia pestis) in Converse County, Wyoming.

Confirming a Cultural Association at the La Prele Mammoth Site (48CO1401), Converse County, Wyoming

Archaeologists have long subjected Clovis megafauna kill/scavenge sites to the highest level of scrutiny. In 1987, a Columbian mammoth (Mammuthus columbi) was found in spatial association with a small artifact assemblage in Converse County, Wyoming. However, due to the small tool assemblage, limited nature of the excavations, and questions about the security of the association between the artifacts and mammoth remains, the site was never included in summaries of human-killed/scavenged megafauna in North America. Here we present the results of four field seasons of new excavations at the La Prele Mammoth site that confirm the presence of an associated cultural occupation based on geologic context, artifact attributes, spatial distributions, protein residue analysis, and lithic microwear analysis. This new work identified a more extensive cultural occupation including the presence of multiple discrete artifact clusters in close proximity to the mammoth bone bed. This study confirms the presence of a second Clovis mammoth kill/scavenge site in Wyoming and shows the value in revisiting proposed terminal Pleistocene kill/scavenge sites.

Endemic chronic wasting disease causes mule deer population decline in Wyoming.

Chronic wasting disease (CWD) is a fatal transmissible spongiform encephalopathy affecting white-tailed deer (Odocoileus virginianus), mule deer (Odocoileus hemionus), Rocky Mountain elk (Cervus elaphus nelsoni), and moose (Alces alces shirasi) in North America. In southeastern Wyoming average annual CWD prevalence in mule deer exceeds 20% and appears to contribute to regional population declines. We determined the effect of CWD on mule deer demography using age-specific, female-only, CWD transition matrix models to estimate the population growth rate (λ). Mule deer were captured from 2010–2014 in southern Converse County Wyoming, USA. Captured adult (≥ 1.5 years old) deer were tested ante-mortem for CWD using tonsil biopsies and monitored using radio telemetry. Mean annual survival rates of CWD-negative and CWD-positive deer were 0.76 and 0.32, respectively. Pregnancy and fawn recruitment were not observed to be influenced by CWD. We estimated λ = 0.79, indicating an annual population decline of 21% under current CWD prevalence levels. A model derived from the demography of only CWD-negative individuals yielded; λ = 1.00, indicating a stable population if CWD were absent. These findings support CWD as a significant contributor to mule deer population decline. Chronic wasting disease is difficult or impossible to eradicate with current tools, given significant environmental contamination, and at present our best recommendation for control of this disease is to minimize spread to new areas and naïve cervid populations.

Natural Fracture Characterization: A Key to Success in an Exploration Play, Converse County, Wyoming: ABSTRACT

Numerous vertical wells drilled in the southern Powder River basin have encountered fractured, tight, overpressured, Cretaceous hydrocarbon reservoirs. These reservoirs demonstrate enhanced productivity and ultimate recovery with little to no water production. Effective exploration and development of these reservoirs includes a systematic approach to characterization and prediction of the fracture system. Surface mapping within Cretaceous units along the southern and western margins of the basin revealed multiple fracture sets related to both regional and local tectonic events. A pre-Laramide regional fracture set oriented at approximately N70{degrees}E is dominant over the mapped 500 square mile area. This set displays a consistent frequency, direction, height. and morphology both in the surface and subsurface. Fractures in early Tertiary rocks within the basin are unidirectionally oriented along a WNW azimuth, a direction also found in the Cretaceous units. Vaster Resources, Inc. is actively exploring fractured reservoirs in the Powder River basin with horizontal wells targeting the Niobrara and Frontier formations. Integration of the detailed surface outcrop studies with regional cross-sections, Landsat lineament analysis, FMS log data, 2D multicomponent/multisource shear wave seismic, and borehole breakouts (to determine present day stress) have been used to successfully predict the orientation, frequency, and degree of openness of themore » subsurface fracture system. The consistency of the fracture system and its positive impact on reservoir productivity significantly enhance the prospectiveness of Cretaceous plays throughout the southern Powder River basin.« less

Natural Fracture Characterization: A Key to Success in an Exploration Play, Converse County, Wyoming: ABSTRACT

Natural Fracture Characterization: A Key to Success in an Exploration Play, Converse County, Wyoming: ABSTRACT

The skull of Cedromus and a review of the Cedromurinae (Rodentia, Sciuridae)

The problematical rodent genus Cedromus Wilson, previously only known from the Orellan of the Great Plains, has been considered a sciurid by some authors and an aplodontid by others. An excellent collection of complete skulls with associated mandibles from Converse County, Wyoming, has provided evidence that this genus is a sciurid but that it represents a new subfamily distinguished from all other sciurids by a unique zygomasseteric structure that closely approaches myomorphy. A second genus, Oligospermophilus Korth, also from the Orellan of the Great Plains, is allocated to this subfamily.Additional and more complete cranial material of the primitive aplodontid Prosciurus indicates that sciurids and aplodontids share a common ancestry and should be included together at least within the same suborder Sciuromorpha.Three species of Cedromus are recognized, C. wardi Wilson, C. wilsoni n. sp., and Cedromus sp.; the latter extends the known temporal range of the genus into the Whitneyan.

Chadronian (Early Oligocene) Magnetostratigraphy of Eastern Wyoming: Implications for the Age of the Eocene-Oligocene Boundary

New magnetostratigraphic studies have been conducted on Early Oligocene sections at Flagstaff Rim and Ledge Creek, Natrona County, Wyoming and the Dilts Ranch, Converse County, Wyoming. Thermal demagnetization has considerably improved the polarity interpretation of Flagstaff Rim, since AF demagnetization had failed to remove a diagenetic normal overprint. The polarity pattern in these sections appears to span the interval from Chron C10r to Chron C15 of the magnetic polarity timescale (31 to 37.5 m.y. based on K-Ar dates from Flagstaff Rim). This additional, more complete magnetostratigraphic evidence shows clearly that the Eocene-Oligocene boundary must lie between 36 and 37 m.y. in age.

Hydrodynamic Control on an Oil Entrapment in Channel Sandstones of the Dakota Sandstone, South Cole Creek Field, Converse County, Wyoming

South Cole Creek field, located in the southwest Powder River Basin of Wyoming has produced 11 million barrels of oil from the Dakota Sandstone. Detailed mapping of rock and reservoir properties including sandstone isopachs, initial potentials, cumulative production, and porosity-permeability data, reveals the existence of channel sandstones with excellent reservoir properties which are surrounded by marine rocks of poorer reservoir properties. The areal extent of the accumulation is controlled by factors other than structure and stratigraphy, as water-bearing channel sandstones exist lateral to and up-dip of producing channel sandstones. By comparing the known accumulation to the theoretical model for fluid flow, it can be shown that hydrodynamics has played an important role in modifying the accumulation at South Cole Creek field.

Diagenesis of Upper Cretaceous Teapot Sandstone, Powder River Basin, Wyoming: ABSTRACT

The Upper Cretaceous Teapot sandstones of Well Draw field, Converse County, Wyoming, are turbidite fan deposits bounded stratigraphically by marine shales. They presently occur from 6,360 to 7,200 ft (1,920 to 2,195 m), dipping to the northwest. Cored samples selected from nonbioturbated A bedsets show that the sandstones are fine to very fine-grained feldspathic litharenites. Major authigenic minerals include carbonate cement, quartz overgrowths, and clay minerals. The clay minerals originated either as alteration rims on detrital silicates or as precipitates from pore fluids. Alteration rims typically consist of illite, smectite, mixed layer illite/smectite, and lesser chlorite. Feldspars are altered to kaolinite. Precipitated clays occur as (1) thin, unoriented, grain coating chlorite and kaolinite, (2) pore lining mixed layer illite/smectite and lesser chlorite oriented with (001) normal to the pore wall, and (3) unoriented, poorly crystalline, pore filling chlorite. The diagenetic sequence is (1) compaction and limited quartz overgrowth development, (2) complete calcite cementation and precipitation of grain-coating clays, (3) dissolution of carbonate cement, (4) precipitation of pore lining and later pore filling clays, and (5) development of second stage quartz overgrowths. Development of silicate alteration rims occurred throughout the diagenetic history. Dissolution of carbonate cement produced the majority of present-day porosity; however, this secondary porosity was reduced by precipitation of clay minerals. In the downdip sandstones, hydrodynamic flow and an increase in the abundance of detrital labile grains have caused an increased abundance of clay mineral precipitates, reducing the reservoir potential. The pore fluids which controlled sandstone diagenesis were likely provided by dewatering and diagenesis of enclosing shales. End_of_Article - Last_Page 465------------

Organic Composition of Some Upper Cretaceous Shale, Powder River Basin, Wyoming

The lower Upper Cretaceous strata in northeastern Wyoming, which have yielded major quantities of oil and gas, were sampled at boreholes in Converse, Johnson, and Weston Counties. Cores of noncalcareous shale of largely nearshore-marine origin were obtained from the Frontier Formation and the overlying Cody Shale at depths of 3,780.6 to 3,879.9 m in Converse County, near the axis of the Powder River basin, and at depths of less than 320 m in Johnson County, on the western flank of the basin. Cores of calcareous and noncalcareous shale representing offshore-marine and nearshore-marine environments were acquired from the Belle Fourche Shale, Greenhorn Formation, and Carlile Shale at depths of less than 270 m in Weston County, on the eastern flank of the Powder River basin. Analyses of the shale for organic carbon content, total pyrolytic hydrocarbon yield, volatile hydrocarbon content, temperature of maximum pyrolytic yield, and vitrinite reflectance indicate that the amount and character of the organic matter in the sampled rocks is related to the content of calcium carbonate, the depositional environment, and the burial depth of the strata. On the east flank of the Powder River basin, calcareous shale of offshore-marine origin contains abundant hydrogen-rich organic matter derived mainly from aquatic plants. Noncalcareous shale of largely nearshore-marine origin, on the west flank of the basin, locally contains significant hydrogen-poor organic matter derived mostly from land plants. The noncalcareous, nearshore-marine shale in the middle of the basin probably contained similar amounts of hydrogen-deficient organic matter prior to deep burial and thermal alteration. The calcareous shale in Weston County is a potentially rich source of oil and gas, but it is thermally immature and is in a very early stage of the hydrocarbon-generation process. The noncalcareous shale in Johnson County is a potential source rock for gas, but also is in an early stage of thermal alteration. In Converse County, the sampled beds are thermally mature and have generated hydrocarbons. The extent of this contribution of hydrocarbons to the commercial petroleum occurrences of the area can be inferred from the composition of the original organic matter in the beds. Furthermore, the degree of thermal alteration of the organic matter at these localities indicates that the depth of the sampled strata was never as great on the flanks of the Powder River basin as in the basin ce ter.

Spearhead Ranch Field, Converse County, Wyoming: ABSTRACT

Spearhead Ranch Field, Converse County, Wyoming: ABSTRACT

Poison Draw Field, Converse County, Wyoming: ABSTRACT

Oil and gas production in Poison Draw field, discovered in 1972, is from the lower sand bed of the Teckla sand member of the Lewis Shale (Late Cretaceous). Oil production has passed the one-million-bbl mark and is expected to exceed eight million bbl of primary production. The pool is contained in a stratigraphic trap formed in a delta-front environment where strong long-shore currents and wave action formed a northwest-southeast trending system of beaches and delta-front bars. The Poison Draw Teckla pool produces from an undersaturated, underpressured sandstone reservoir. Development drilling on the east updip margin and in the northern part of the field is still active. The recent increases in crude oil prices have greatly enhanced the economic potential of the field. One other Teckla sand pool already has been found and further exploration drilling may find additional Teckla sand pools in the southern Powder River basin. End_of_Article - Last_Page 907------------

Brooks Ranch Oil Field, Natrona and Converse Counties, Wyoming: ABSTRACT

The Brooks Ranch field is a stratigraphic-type oil field in T. 33 N., R. 77 W., Natrona and Converse counties, Wyoming. Field production is from the Upper Cretaceous Second Frontier sandstone. The sandstone thins eastward to a wedge-edge from a gross thickness of 25 feet at the western margin of the field. The oil accumulation is controlled by an anticlinal axis which intersects the stratigraphic thinning. The productive area of the field will exceed 3,000 acres. The average permeability of 5 millidarcys is low, whereas the porosity ranges between 18 and 20 per cent. Initial production varies considerably from well to well, averaging about 100 barrels of oil per day per well. The discovery well drilled by Dan C. Morton in March, 1957, is located in the SE., SE., SE., Sec. 9. The field now has 50 producing wells. End_of_Article - Last_Page 1095------------

Big Muddy Water Flood

Abstract This paper presents a summary of the production and waterflood history of the Second Wall Creek Reservoir in the Big Muddy field. This highly successful Eastern Wyoming water flood has doubled the production from the Wall Creek in less than two years of operation. An outline of the laboratory and reservoir studies which culminated in the installation of a pilot water flood in 1953 is presented. Pertinent reservoir data, such as oil and water saturations, are given. The development program and current production practices of the waterflood program are also presented. The primary and waterflood performance is shown for several individual wells and for the entire flood. Cumulative waterflood recoveries and the estimated ultimate recoveries are given, in conjunction with the current development and operating costs and the future economics of the waterflood program. Introduction The Big Muddy oil field is located about 4 miles west of Glenrock in Converse County, Wyo. The field was discovered in 1916, although Wall Creek production was not encountered until 1917, when State 10 Lease Well No. 1 was brought in flowing at a rate of 150 BOPD. This discovery touched off a prolific drilling program and brought about one of Wyoming's famous oil booms. Most of the wells drilled to the Wall Creek were located along the crest of the structure and were generally spaced on a 10-acre pattern as shown in Fig. 1. Full development of acreage did not take place on leases located on the flanks of the structure. However, lease line drilling was sufficient to prove up this peripheral area. The majority of wells were drilled with cable tools to the top of the sand. Casing was then run and the wells tailed in to a depth 50 to 60 ft below the sand top. A typical casing program consists of 40 ft of 20 in. surface pipe, 250 ft of 15 1/2 in. pipe to seal off a good water sand, 1,000 ft of 12 1/2 in. pipe to combat hole cavings and finally 3,000 ft of 6 1/4 in. casing set on top of the sand. There is little record of cementing having been done in the early wells.

Discoveries--Glenrock Area--Converse County, Wyoming: ABSTRACT

Five wells constitute the discoveries of the Glenrock area, located on the south rim of the Powder River Basin, Converse County, Wyoming. Production is obtained from sands in the Cretaceous Muddy and Dakota horizons on three separate structural features. The Glenrock field proper is a faulted (?) block east of, and associated with, the large Big Muddy uplift. South Glenrock is producing from a structural nose extending eastward from the east end of Big Muddy. The Deer Creek field is a separate feature south of a sharp syncline separating it from Big Muddy, being less than two miles from the north front of the northern Laramie Mountains. Production varies from approximately 7,200 feet at Glenrock through the depths 5,800-5,900 feet at South Glenrock to 5,100 feet at Deer C eek. The discovery well for the entire Glenrock area was the Steelco McDonald No. 1, completed December 27, 1949, from the Muddy sand. Slides showing a map of the region and its relationship to the Bid Muddy oil field, which was discovered in 1916, and a cross section correlating the discovery wells point to the key geologic features. Kodachrome slides of operations and cores illustrate the developments of the area. End_of_Article - Last_Page 1104------------

Cretaceous Eocene correlation in New Mexico, Wyoming, Montana, Alberta

Research Article| January 01, 1914 Cretaceous Eocene correlation in New Mexico, Wyoming, Montana, Alberta BARNUM BROWN BARNUM BROWN Search for other works by this author on: GSW Google Scholar GSA Bulletin (1914) 25 (1): 355–380. https://doi.org/10.1130/GSAB-25-355 Article history received: 14 Jun 1914 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation BARNUM BROWN; Cretaceous Eocene correlation in New Mexico, Wyoming, Montana, Alberta. GSA Bulletin 1914;; 25 (1): 355–380. doi: https://doi.org/10.1130/GSAB-25-355 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu nav search search input Search input auto suggest search filter All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract IntroductionFor the American Museum I have been continuously engaged since June, 1900, in the exploration of the geology, flora, and fauna of three great formations which in their animal and plant life bridge over the passage from Cretaceous to Eocene time, as determined by comparison with the life of the same epochs in Europe. I propose to compare these formations with each other and with the typical Lance Creek formation of Wyoming. These formations are: Years Hell Creek formation of northern Montana 1902–1909 Series embracing in descending order Paskapoo, Edmonton, Fort Pierre (upper), Belly River (intercalation). Fort Pierre (upper) of Red Deer River, Alberta 1909–1913 Ojo Alamo formation of northern New Mexico 1904 Lance Creek formation of Converse County, Wyoming 1900–1901 Years Hell Creek formation of northern Montana 1902–1909 Series embracing in descending order Paskapoo, Edmonton, Fort Pierre (upper), Belly River (intercalation). Fort Pierre (upper) of Red Deer River, Alberta 1909–1913 Ojo Alamo formation of northern New Mexico 1904 Lance Creek formation of Converse County, Wyoming 1900–1901 View LargeI have determined the geologic sequence in each of these formations and the succession of the species of reptiles. The mammals have been determined with . . . This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not currently have access to this article.

Expeditions to the Miocene of Wyoming and the Chalk Beds of Kansas

ON July 28 I reached my station at Edgemont, S. D. The next day I drove out to my son Charlie's cabin, thirty-five miles west, on Old Woman creek, in Converse county, Wyoming. I found that, with the assistance of my youngest son, Levi, and Conrad Jesperson, of Lawrence, he had secured a complete series of caudal vertebrae and bones of the pelvis and hind limbs of the great swimming dinosaur Trachodon; and three-quarters of a fine skull, six and a' half feet long, of Triceratops, the huge three-horned lizard of the Laramie. The Trachodon material has gone to Munich to complete a composite open mount, I having sent the other material last year. The magnificent skeleton secured last year by my son Charlie went to the Senckenberg Museum. I believe these are the only complete skeletons of American dinosaurs in Europe. The seven-foot skull I discovered last year of Triceratops, which I was preparing for the Victoria Memorial Museum, was destroyed last year when the brick walls of the building at 617 Vermont street, in which it was housed, was blown in on top of it by a cyclone-a great loss to science and myself. Having gone over the Laramie beds thoroughly during the last four years, on the fourth of August we moved over to the old deserted Seaman ranch on Sage creek, a branch of Old Woman creek, in Converse county, Wyoming. These beds are known as the Upper Harrison beds. The first day in this rich field that has been but little explored, I discovered the skeleton of the great titanothere Brontotherium gigas. The pelvic arch was partly exposed and measured four feet across the illia; the complete skull; vertebral column, with ribs continuous to first caudal; one humerus, and other bones. The lower limbs were absent. This specimen, according to Doctor Matthew, curator of vertebrate palmontology in the American Museuim of Natural History, New York, is the best single specimen known, and is the size of their mounted composite specimen that measures over twelve feet long and about eight feet high. We are now preparing this noble specimen for the Victoria Memorial Museum at Ottawa, Canada, and will secure casts of the feet from the American Museum specimen.

Some Small Natural Bridges in Eastern Wyoming

Natural bridges have been described at length by Mr. Herdman F. Cleland2 in a paper read before the Geological Society of America, December 29, 1909, and less extensively from time to time by Walcott, Cummings, Pogue, and others.3 Small bridges observed by D. E. Winchester and the writer, in Weston and Converse counties, Wyoming, seem to justify a brief description, as they belong to a little different class from any discussed by these writers. Of the different types enumerated the bridges in Wyoming more nearly resemble the one formed by a petrified log spanning a ravine in the petrified forest of Arizona, described by Mr. Cleland,4 but differ from it in that they owe their existence to indurated masses or concretions instead of to a petrified log as in the case cited by Mr. Cleland. The beds of the Fort Union and Lance formations of this district (eastern Wyoming) contain a predominance of soft sandstone and sandy shale. Almost everywhere in the sandstone are inclusions of concretions and indurated masses. They present a great variety of forms. Some are nearly perfect spheres from the size of a marble to eighteen or twenty inches in diameter; others are more irregular and vary from the shape of a log to very irregular masses sometimes several hundred feet in length. These larger