Judith River Formation Research Articles

The smallest ceratopsid skull–Judith River Formation of Alberta

A partial skull found at Dinosaur Provincial Park, Alberta, in Upper Cretaceous (Campanian) sediments is the smallest specimen of a ceratopsid ever found, belonging to an animal about 1.1 m long. It represents an animal probably less than 2 years old, one fifth of its adult size. The shape of the squamosal and the thinness of the parietal suggest a tentative referral to Monoclonius. Strong positive allometric growth of the parietal fenestra is inferred.

Judith River Formation Beneath Fort Peck Indian Reservation--Proven High Plains Gas Frontier in Northeastern Montana: ABSTRACT

As one of the progradational sequences in the Late Cretaceous, the Claggett-Judith River cycle created potential reservoirs for shallow biogenic gas. From west to east across the Fort Peck Reservation in northeastern Montana, in a distance of 75 mi (121 km), the Judith River Formation changes from a 350-ft (107-m) accumulation of fine-grained nonmarine clastics, to a 130-ft (39-m) deposit of fine-grained sandstone. Three units are present in the subsurface of the central part of the reservation. A continuous basal sandstone, 30-130 ft (9-39 m) thick, formed in a coastal environment. This unit thickens in the direction of progradation, which may indicate the addition of sand bodies in a shelf environment. The middle unit is a 20 to 50-ft (6 to 15-m) sequence of shale and siltstone. Capping the Judith River is a sandstone 20-50 ft (6-15 m) thick, which formed either as a shore facies in the regressive cycle or as a shelf sandstone prior to the final Cretaceous transgression that deposited the overlying Bearpaw Shale. Stratigraphic traps exist in the upper and lower sandstone units due to variation in grain size and clay content associated with the progradational facies changes. In addition, Laramide structures associated with the Poplarmore » dome and Wolf Creek nose have created local trapping mechanisms. Judith River gas has been produced for operational use since 1952 in the East Poplar field. Shows have been reported in central reservation wells, although high mud weights and deeper exploration targets have prevented adequate evaluation of the Judith River gas frontier.« less

The Petrofka landslide, Saskatchewan

Both abutments and all piers of the Petrofka bridge are on a landslide. The bridge has performed satisfactorily for 23 years, indicating the factor of safety of the Petrofka landslide is greater than unity. This stability is abnormal because landslide slopes on bedrock clays (shale) in this region are notoriously unstable. A dormant landslide is difficult to analyze because the input parameters must represent a condition of limiting equilibrium.The Petrofka landslide is 70 m high, 880 m long, 3000 m wide, and up to 100 m thick. The shear zone is in highly plastic, montmorillonitic clays in an unnamed formation of probable Tertiary age. The Upper Cretaceous Lea Park, Judith River, and Bearpaw formations and the unnamed formation underly the landslide and are restricted to a collapse structure resulting from dissolution of Devonian evaporites.A retrogressive mechanism developed as valley downcutting progressed. The pore-water pressures could be estimated from the hydraulic head in the artesian aquifer of the Judith River Formation. The hydraulic head was maintained at critical as the valley deepened until the Judith River Formation was eroded downstream. The landslide was active for only a few hundred years, between 11 500 and 11 000 years ago.The back-calculated effective angle of friction for the bedrock clay (shale) was estimated at between 5.6° and 6.5°, assuming c′ = 0, resulting in a present-day factor of safety between 1.2 and 1.3. Key words: back analysis, dormant landslide, collapse structure, artesian pressure, historical simulation, residual shear strength.

Latest Cretaceous occurrence of nodosaurid ankylosaurs (Dinosauria, Ornithischia) in Western North America and the gradual extinction of the dinosaurs

ABSTRACT The presence of nodosaurid ankylosaurs in the Lance, Hell Creek, and Laramie formations of western North America is confirmed, thereby extending the geochronological range of this family into the Maastrichtian (Lancian). The material includes a cervical spine and a skull referable to Edmontonia sp., and numerous teeth, plates and a basioccipital, which are questionably assigned to Edmontonia sp. Comparison of the amount of nodosaurid material known from the Judith River Formation (Campanian) with that from the Lancian deposits indicates a substantial decrease in the relative abundance of nodosaurids in the Maastrichtian. Furthermore, the stratigraphic distribution of these nodosaurs is apparently limited to the lower part of the Lancian deposits, suggesting that they became extinct before the end of the Cretaceous. If true, this would support the hypothesis that the dinosaur extinction at the end of the Maastrichtian was gradual, not catastrophic.

Stenonychosaurus inequalis (Saurischia: Theropoda) from the Judith River (Oldman) Formation of Alberta: new findings on metatarsal structure

A partial foot of Stenonychosaurus from the Judith River (Oldman) Formation, Dinosaur Provincial Park, Alberta, shows features in the metatarsus that have not previously been recognized. These include compression of metatarsal II and exclusion of the proximal half of metatarsal III from the anterior (= dorsal) surface of the metatarsus. Exclusion from the anterior surface of metatarsal III to this extent is unprecedented among theropods and further underscores the distinctiveness of the Sauromithoididae.

Sedimentology of Paleochannels on Foreland Coastal Plain, Judith River Formation (Upper Cretaceous), Southeast Alberta: ABSTRACT

The upper 90 m (295 ft) of the sub-Bearpaw Judith River Formation, continuously exposed in the badlands along the Red Deer River 185 km (115 mi) east of Calgary, is famous for the unrivaled assemblage of dinosaur fossils. Dinosaur Provincial Park presents a rare opportunity to view the architecture of a foreland coastal-plain sequence as well as to clarify the origin and distribution of subbituminous coal zones and gas reservoirs associated with this formation across southeast Alberta. The distal reaches of paleodrainage from the developing Cordillera to the Western Interior seaway are being examined by north-south traverses across the badlands. Sharp-based paleochannel units, enclosed by rooted, olive-gray mudstone sequences that are commonly 4-6 m (13-20 ft) thick, vary between 2 end members. The first contains laterally accreted sand-mud couplets with abundant macrofloral debris, and represents cyclical, low-energy growth of point bars, possibly with an estuarine influence. The second, mainly comprising cosets of large trough cross-beds with mudstone intraclasts, was formed by episodic aggradation of high-energy systems. An intermediate composite type displays evidence for an energy increase as channel sinuosity decreased. This variation in paleochannel type is a tributed to alternating alluviation/rejuvenation associated with an unstable base level. Coal zones and potential reservoirs appear to be associated with the transgressive and regressive phases, respectively, of the Bearpaw coast. Amalgamation of paleochannels--marked by laterally extensive horizons of bone fragments, lithic and intraclastic gravel--is more common seaward over the axial region of the Sweetgrass arch. End_of_Article - Last_Page 496------------

Canadian journal of political science: Donald E. Blake, ‘The Consistency of Inconsistency: Party Identification in Federal and Provincial Politics’, XV:4, December 1982, pp. 691–710

Using single stratigraphic methods in the geological analysis of incompletely or poorly exposed sedimentary successions can lead to non-unique interpretations and increased potential for error. In this study of the Mesaverde outcrops (Eagle Formation, the Claggett Tongue of the Cody Shale, and the Judith River Formation) in the northern Bighorn Basin of Wyoming, which has limited and variable quality exposures, an integrated method utilizing sedimentological, ichnological, and palynological data was used in order to overcome these limitations. Ten facies are identified within the exposures examined. These facies are arranged so as to depict a broadly distal to proximal gradient recording the progradation of fluvial-dominated deltas into a shallow marine environment. The utilization of a Zobaa Ternary Plot and Calgary and Brown factor analysis (CABFAC) for palynofacies analysis in the study allows for corroboration of the lithological interpretation, which has not been possible in previous studies of correlative outcrops. It also enables the identification of environmental trends not seen in the lithological analysis, thus allowing for a more robust stratigraphic analysis. The methods used in this study not only decrease the inherent error in paleoenvironmental analysis of poorly exposed areas and thereby decrease variability in paleoenvironmental interpretations, but also allow identification of changes that are not evident from a single method approach. The result of utilizing this approach in areas of limited or poor quality exposure is a more comprehensive and well-informed regional stratigraphic framework.

The Denholm landslide, Saskatchewan. Part I: Geology

The Denholm landslide, whose surface is composed of scarps, ridges, and elongated depressions, is 160 m high, 2000 m wide, and up to 100 m thick. The shear zone is in silty, montomorillonitic clay of the upper part of the Lea Park Formation and Upper Colorado Group unit. The Upper Cretaceous Judith River Formation and the Quaternary Empress, Sutherland, and Saskatoon groups were affected by the landslide. Although these sediments were fractured and gravity faulted by tension when the landslide moved, they can be readily traced through the landslide, particularly the upper part. The scarps (gravity faults), ridges (horsts), and elongated depressions (grabens) are the surface expression of tension resulting from the stretching of beds during the landslide.The movement of the landslide is thought to have started when the North Saskatchewan spillway eroded to the level of the present shear zone about 11 000 years ago (established by radiocarbon dating) and is believed to have stopped in recent time. During this time, it moved about 390 m across the North Saskatchewan River alluvium at an average rate of 35 mm per year. As the landslide moved across the valley, it encountered deposition of alluvium at an average rate of about 2.4 mm per year which resulted in the curved shear zone on the alluvium. Keywords: retrogressive landslide, shale-alluvium, displacement, rate, age.

New data on pachycephalosaurid dinosaurs (Reptilia: Ornithischia) from North America

In this paper several new significant specimens of pachycephalosaurid dinosaurs from Upper Cretaceous strata of Canada and the United States are described and figured. The domes of an unusual pachycephalosaurid from the Judith River Formation (Campanian) of Alberta show a slightly thickened frontal with an ornamentation of bony tubercles; they are referred to a new genus. A new genus of Pachycephalosauridae is described from the Hell Creek Formation (Maestrichtian) of Montana; it has horn-like projections on the squamosal. Sutural fusion between the quadrate and squamosal of Pachycephalosaurus is reported; this is an unusual condition among the Ornithischia. The biological significance of certain cranial features is considered.

Update on Coal in Big Horn Basin, Montana and Wyoming: ABSTRACT

The Big Horn Coal basin is located within the topographic and structural basin of the same name and is defined by the limits of the Upper Cretaceous Mesaverde Formation in northwestern Wyoming and the Eagle Sandstone in south-central Montana. Eight coalfields in Wyoming and two in Montana occur in this large, asymmetrical, northwest-trending synclinal coal basin. While coal-bearing rocks are found in the Cloverly, Frontier, Lance, Willwood, Tatman, Judith River, Fort Union, Meeteetse, Eagle Sandstone, and Mesaverde formations, only the last four of these formations contain coal beds of economic significance. The coal in this basin ranges in rank from high volatile C bituminous (based primarily on resistance to weathering) to subbituminous B coal. In general, the Mesaverde and Eagle coals are highest in heat content, averaging over 10,500 Btu/lb; the Fort Union coals in the Red Lodge-Bear Creek and Grass Creek fields average about 10,200 Btu/lb and are second highest in heating value. The Meeteetse Formation contains coals that average 9,800 Btu/lb, the lowest heating values in the basin. An average heating value for all coal in the basin is slightly less than 10,000 Btu/lb. The average sulfur content of all coals in this basin is less than 1%, with a range of 0.4 to 2.2%. For coals of economic interest in the basin, the Forth Union coals in the Grass Creek field are lowest in sulfur conte t, averaging 0.4%; the Fort Union coals in the Red Lodge-Bear Creek field are highest in sulfur, averaging about 1.9%. Coal mining in the Big Horn Coal basin began in the late 1880s in the Red Lodge field and has continued to the present. Almost 53 million tons of coal have been mined in the basin; nearly 78% of this production (41 million tons) is from bituminous Fort Union coal beds in tho Red Lodge-Bear Creek and Bridger coal fields, Montana. Nearly all the production in Wyoming has been from Mesaverde coals in the Gebo field. Most of the coal was mined underground and was used by the railroads; maximum production for the entire basin was attained in 1920, when 2.4 million tons were produced. The only coal activity in the Big Horn basin at present is a small strip mine operated by Northwestern Resources at Grass Creek, Wyoming. Original in-place resources for the Big Horn Coal basin are given by rank of coal: 1,265.12 million tons of bituminous coal resources have been calculated for the Silvertip field, Wyoming, and the Red Lodge-Bear Creek and Bridger fields, Montana; 563.78 million tons of subbituminous resources have been calculated for the remaining Wyoming coal fields. Remaining recoverable bituminous resources in coal beds over 28 in. (71 cm) thick and at depths less than 1,000 ft (300 m) are estimated at 400 million tons. Remaining recoverable subbituminous resources in coal beds over 5 ft (1.5 m) thick and under less than 1,000 ft (300 m) of overburden are estimated at 41.7 million tons, of which 18.6 million tons is considered strippable. End_of_Article - Last_Page 1345------------

Conventional and Low-Permeability Reservoirs of Shallow Gas in the Northern Great Plains

Summary Significant resources of natural gas occur at shallow depths [less than 4,000 ft (1200 m)] within a large area of the northern Great Plains. Reservoir properties are controlled mainly by the depositional environments in which source and reservoir rocks accumulated. Exploration and development of potential gas resources depends on successful prediction of the physical characteristics and distribution of gas-bearing rocks. Introduction Major resources of natural gas trapped in low-permeability, low-pressure reservoirs underlie large areas of the northern Great Plains at depths of less than 4,000 ft (1200 m). Rising gas prices and accelerated drilling suggest that the area may be of considerable economic importance in the near future. Effective exploration for low-permeability (unconventional) reservoirs depends on successful prediction of the distribution and physical characteristics of the gas-bearing rocks and on carefully managed completion and development techniques. The purpose of this paper is to compare. describe, and contrast conventional and low-permeability shallow gas reservoirs to provide geologic information useful to exploration and development of these resources. Potential unconventional reservoirs in the northern Great Plains occur within strata from the base of the Mowry Shale (Upper Cretaceous) to the top of the Judith River Formation (Upper Cretaceous). These reservoirs are thin. discontinuous siltstone and sandstone laminae enclosed in thick sequences of offshore marine shale. Gas occurs in a sedimentary section that is immature with respect to thermal oil and gas generation. The gas in both conventional and unconventional reservoirs was generated during the breakdown of organic matter by anaerobie microorganisms at shallow depths in accumulating sediments and is referred to as biogenic gas. The biogenic gas is composed predominantly of methane (C1/C1 through 5 greater than 0.99 enriched in the light isotope 12 C ( 13 C1 = -60 to -70 ppt). The occurrence of natural gas and the physical properties of the gas-bearing reservoirs are controlled chiefly by the depositional environments in which source and reservoir rocks accumulated. Examples for comparison have been selected from the Eagle Sandstone/Telegraph Creek Formation stratigraphic interval because equivalent rocks produce economic quantities of gas from three major reservoir types:conventional reservoirs in coastal deposits are illustrated with an example from the Eagle Sandstone in Tiger Ridge field. Bearpaw Mountains area, north-central Montana (Fig. 1 );shelf sandstone reservoirs of intermediate quality are exemplified by a coarsening-upward sequence in the Shannon Sandstone Member of the Gammon Shale from Bowdoin Dome, north central Montana (Fig. 1);a productive siltstone/shale reservoir in the Gammon Shale at Little Missouri field in southwestern North Dakota (Fig. 1) provides an example of a low-permeability shallow gas reservoir. Comparable data for each reservoir type are listed in Table Conventional Reservoirs in Coastal Sandstones Conventional reservoirs in the Eagle/Telegraph Creek stratigraphic interval are confined to coastal sandstones of the Eagle Sandstone that occur in a north-south-trending zone through central Montana (Fig. 1). This zone approximates the position of the fluctuating shoreline during a major marine regression. Sandstones in this zone are widespread (blanketlike) bodies, more than 40 ft (12 m) thick, deposited under relatively high-energy conditions along the shoreline. The dominant transporting force was wave action that generated longshore and tip currents.

A giant pterosaur (Reptilia: Archosauria) from the Judith River (Oldman) Formation of Alberta

A specimen discovered in the Judith River Formation, Dinosaur Provincial Park, documents the presence of a giant pterosaur in Alberta during Campanian times. The element lacks both ends, but is probably a femur. The size suggests that the wingspan of the animal from which it was derived would have been about 13 m. A diagnostic vertebra from a smaller specimen demonstrates that the giant pterosaur is probably Quetzalcoatlus.

Shallow, Low-Permeability Reservoirs of Northern Great Plains--Assessment of Their Natural Gas Resources

Major resources of natural gas are entrapped in low-permeability, low-pressure reservoirs at depths less than 4,000 ft (1,200 m) in the northern Great Plains. This shallow gas is the product of the immature stage of hydrocarbon generation and is referred to as biogenic gas. Prospective low-permeability, gas-bearing reservoirs range in age from late Early to Late Cretaceous and include most of the section from the base of the Mowry Shale to the top of the Judith River Formation. For detailed examination, the potential reservoir section was divided into five intervals represented by one or more formations and their correlatives. The intervals selected correspond to (1) Mowry Shale, (2) Belle Fourche Shale and Greenhorn Formation, (3) Carlile Shale, (4) Niobrara and Telegrap Creek Formations and Eagle Sandstone, and (5) Claggett Shale and Judith River Formation and their equivalents. Within each interval, several different facies are developed. The following facies were identified and mapped for each interval: nonmarine rocks, coastal sandstones, shelf sandstones, siltstones, shales, and chalks. Two types of shelf sandstone were differentiated but generally not mapped separately because of lack of well log control. The sand ridge type has reservoir properties comparable to coastal sandstones and occurs as isolated tongues as much as 75 ft (23 m) thick. The second type of shelf sandstone is in beds commonly less than 1 in. (3 cm) thick which are interbedded with shale and contain a high content of allogenic silt- and clay-size material. It is impossible to differentiate these individual beds on conventional well logs. The siltstone and shale facies are grouped to ether because conventional logs cannot distinguish between these two rock types, particularly when they are interbedded. For future evaluation of natural gas resources from low-permeability reservoirs, it will be necessary to differentiate between the siltstone and shale facies and to identify individual beds, particularly very thin ones, within the shelf sandstone facies. Each facies contains distinct reservoir types, some of which are low in permeability. The most promising low-permeability reservoirs are developed in the shelf sandstone, siltstone, and chalk facies. Reservoirs within these facies are particularly attractive because they are enveloped by thick sequences of shale which serve as both a source and a seal for the gas. When naturally fractured, these shales also may be low-productivity gas reservoirs similar to the Devonian shales of the Appalachian basin. In addition, facies with low-permeability reservoirs are present over most of the study area when maps for all of the intervals are combined. Natural gas is produced from low-permeability reservoirs in the northern Great Plains in the southern part of western Canada. Established production covers an area of approximately 8,000 sq mi (20,700 sq km) where reported recoverable reserves average as much as 2 Bcf sq mi. Using these reserve data as an analog, the United States portion may contain resources of natural gas in excess of 100 Tcf. The volume of recoverable gas in the United States will depend on the development of improved recovery technology and higher gas prices relative to costs.

A highway cut failure in Cretaceous sediments at Maymont, Saskatchewan

In 1973 the Saskatchewan Department of Highways began construction of a crossing over the North Saskatchewan River at Maymont, Saskatchewan. The south approach to the river required a cut some 20 m in depth at the top edge of the valley and when the excavation reached the design elevation a massive failure occurred on one of the backslopes. The major portion of the slip surface followed a slickensided clay shale zone. An analysis of the failure indicates residual angles of shearing resistance were being mobilized. The reason for mobilizing only the residual strength is attributed to previous shearing arising from glacial ice-thrusting.The sliding occurred entirely within the sediments of the nonmarine Upper Cretaceous Judith River Formation, but the strengths mobilized were essentially the same as those mobilized by slides in the marine Upper Cretaceous Bearpaw and Lea Park Formations. Negative water pressures arising from the stress change due to excavating did not appear to influence the stability. Direct shear box tests on natural slickensided surfaces gave strengths higher than required for a safety factor of unity. The testing of precut surfaces gave results that seem to correlate more closely with the field residual strengths. Furthermore, the Maymont case history clearly illustrates the need for identifying geological details and demonstrates the engineering significance of glacial ice-thrusting.

Notes on pachycephalosaurid dinosaurs (Reptilia: Ornithischia) from North America, with comments on their status as ornithopods

Several biologically significant domes of pachycephalosaurid dinosaurs are described and figured. One unusual specimen from the Oldman Formation (Upper Cretaceous) of Alberta is placed into a new genus and another specimen from the same formation is assigned to a new species of Stegoceras. Domes referable to Stegoceras sp. (Judith River and Hell Creek Formations) are the first conclusive evidence of the presence of this genus in the United States. A large dome from the Oldman Formation of Alberta is referred to Pachycephalosaurus; this specimen is the oldest described to date and is the first record of this genus in Canada.Endocranial casts of Yaverlandia bitholus and Stegoceras validus are described along with a discussion of endocranial trends in pachycephalosaurids. The separation between the cerebrum and cerebellum found in Yaverlandia, and typical of ornithopods in general, is lacking in Stegoceras and Pachycephalosaurus. The loss of this separation may be the result of head butting.The family Pachycephalosauridae possesses sufficient ornithopod characters to justify their retention in that suborder. It does, however, represent an aberrant side branch of ornithopod evolution, which can best be visualized taxonomically by placing this family into a separate infraorder within the Ornithopoda.

Mammals from the Upper Cretaceous Oldmae Formation, Alberta. I. Alphadon Simpson (Marsupialia)

New mammalian fossils from the Upper Cretaceous Oldman Formation, Alberta, pertain to three species of the marsupial Alphadon Simpson. One of these species, A. praesagus (Russell), is ancestral to the Lancian A. rhaister Clemens. The second, closely related but not ancestral to the Lancian A. marshi Simpson, is new, and the third, A. halleyi Sahni, is closely related to the Lancian A. lulli Clemens, as had been earlier supposed from fossils from the Judith River Formation, Montana. The phylogenetic relationships of Alphadon are discussed.

Additional fish recordsfrom the Judith River Formation (Campanian) of Montana

The recent recovery of additional fish remains from several fossil sites in Blaine County. Montana, allows us to add a new species of selachian and the occurrence of two genera of Chimaeriformes to the total vertebrate faunal assemblage of the Judith River Formation (Campanian). The new selachian genus is: Chiloscyllium missouriensis, a representative of the family: Orectolobidae. In association with the new orectolobid, there are representatives of the Chimaeroids: Ischyodus bifurcatus Case, and Elasmodus cf. greenoughi Agassiz. These new additions increase the total vertebratefaunnal assemblage of the Judith River Formation to twenty species.

A new small theropod dinosaur from the Judith River Formation (Campanian) of Alberta Canada

A new small theropod dinosaur, documented by an incomplete skeleton and three frontals, is described from the Judith River Formation (Upper Cretaceous: Campanian) of south-central Alberta. It is distinguished from both Stenonychosaurus and Dromaeosaurus by the structure of the frontal and by the marginal dentition. It resembles Stenonychosaurus in the structure of the frontal and the Dromaeosauridae in the shape of the endocranial cavity and other skeletal features. The material is referred to a new genus and species of the Dromaeosauridae.

Lithostratigraphic nomenclature of the Upper Cretaceous Judith River Formation in southern Alberta; philosophy and practice

ABSTRACT Lithostratigraphic nomenclature in the Upper Cretaceous Montana Group in the southern Plains of Alberta is ambiguous and confusing. The name Belly has not been used consistently and has outlived its usefulness. The names Oldman and Foremost are vague, ill-defined terms whose use should be discontinued. The name should be employed for the entire interval between the Pakowki Formation below and the Bearpaw Formation above. It has been applied consistently to this stratigraphic interval in northern Montana and, at times, in southern Alberta, for the past 100 years and its use would serve to unify and simplify the nomenclature throughout this area. Use of the name Belly should be retained in the Foothills of southwestern Alberta, beyond the western limit of the Pakowki Formation, where the Judith River and Milk River Formations are not differentiated.

Dentaries of small theropods from the Judith River Formation (Campanian) of Alberta, Canada

Three dentaries of small theropod dinosaurs from the Judith River Formation of Alberta are described and their taxonomy is discussed. Two are referable to the Dromaeosauridae (Dromaeosaurus sp.) and the other to the Saurornithoididae. The structural differences seem to support recognition of two distinct families, Dromaeosauridae and Saurornithoididae, as proposed by some authors on the basis of other structural differences.