Other important sources of data to constrain fold geometry are geological mapping [e.g., Groshong, 2006; Woodward et al., 1989] and well logging [e.g., Serra, 1984]. Subtle features of the fold between cross sections are not captured by these methods. Tectonic map of the northeastern edge of the Bighorn Basin showing the location of Sheep Mountain anticline. Working off-campus? Sheep Mountain. The Sheep Mountain anticline, in the Bighorn Basin of Wyoming, formed during the Laramide orogeny. However, it is impossible to base the down‐plunge view on data from a swath spanning more than 1 km along the fold trend, due to the noncylindrical nature of the fold, emphasizing the need to consider the fold shape in a fully 3‐D manner. The prominent hill to the east is known as Sheep Mountain. comment type: geology: comment: geol.desc: placer-fossil-beach and marine: comment type: geology: comment: Because most data points are projected down and in, toward the core of the fold, a surface model at this stratigraphic level does not leave much distance between forelimb and backlimb data points open to interpolation. The generation of 3‐D surface models from subparallel 2‐D cross sections results in a directional bias, so surfaces constructed in this manner may fail to capture the full 3‐D character of fold geometry. The 3‐D geometric techniques such as the equivalent dip domain method [Carrera et al., 2009] have been suggested to overcome some of the limitations of sequential balanced cross sections; however, such methods are adequate only for relatively simple folds. Imprecise constraint here could be gathered by extrapolating steeply dipping forelimb points from the southeast. Bedding surfaces that provide additional constraint on fold geometry often are exposed on the downdip side of these ridges. Stanford Rock Fracture Project Vol. Doyle, A B. Stratigraphy and depositional environments of Jurassic Gypsum Spring and Sundance Formations, Sheep Mountain anticline area, Big Horn County, Wyoming. [40] Data decimation is necessary to achieve a numerically feasible and stable interpolation. Data points are decimated such that strike and dip measurements (slope constraints) are input first. Irregular weathering patterns make measurement of strike and dip difficult. [2009] address this issue at Raplee Ridge by simultaneously interpolating multiple surfaces while applying inequality constraints to intervening layer thicknesses to maintain a physically realistic model without surface interpenetration or excessive thinning or thickening. Access & Use Information. [2007b], by printing hill shade images generated from the 1 m DEM on a 42 inch plotter at a scale of roughly 4000:1, on which individual outcrops more than 2–3 m across may be identified. The SMA survey consisted of 14 flight lines to cover the primary area, and five additional flight lines to provide additional coverage on the steep topography of the anticlinal forelimb north of Sheep Canyon. About 30 such points were identified and discarded from the constraint set. [1996] model. No significant trend is observed in the Paleozoic section (Figure 6a), but in the Mesozoic section (Figure 7a), subtle thinning to the southeast is suggested by measurements in the backlimb. To the northwest, the study area is terminated because problems arise apparently due to noncylindrical fold geometry. In regions of dense data coverage, an MCS surface will capture such zones of greater and lesser curvature in order to honor constraints; however, where data are limited, the MCS method, by definition, creates a broad hinge region in which curvature is distributed to the greatest extent possible. Regularization is critical to generate a smooth interpolated surface from noisy data. For this reason, it would have been preferable to model one of the nearby ridge‐forming units of the Gypsum Springs Formation (e.g., cyan). In calculating the mean gradient, we disregard triangles with high aspect ratios, which are found only on the periphery of outcrops and are subject to error because peripheral points may easily be misidentified and therefore not represent the bedding surface. Although the method has limitations, the resulting surface captures details of fold geometry that are not represented in models developed using traditional methods. Intermediate (class 1c) and extreme (classes 1a and 3) fold types are characterized by more complicated relationships between bed thickness and dip isogon orientation, and therefore do not lend themselves to straightforward projection between folded surfaces. [1996] do not present the locations or density of data on which cross sections are based, but there is little doubt that their data lacked the density or precision of ALSM. google_color_link = "663300"; [6] Challenges arise, however, because not all outcrop exposures correspond to the same stratigraphic surface. Bibliographic Reference: Hausel, W.D., 1991, Sheep Mountain copper mine, Medicine Bow Mountains, Wyoming: Geological Survey of Wyoming [Wyoming State Geological Survey] Mineral Report 91-1, 5 p. Approximately half of the points extracted from the DEM (258,769) represent the top of the Tensleep Sandstone (mapped orange), while the fewest points (167) represent the surface in the Gypsum Springs Formation mapped in gold. Additionally, outcrops to the northwest are poorly distributed, limited almost entirely to the ridge forming Frontier Formation. Horizontal dashed lines represent the mean thickness of each interval, corresponding to the symbol on the right. Sheep Mountain The Sheep Mountain Anticline is situated between the towns of Lovell and Greybull in the northwest part of Wyoming; its long, narrow, and perfectly straight crest is an easily recognizable sight from many areas around the Big Horn Basin. The ALTM system can operate at frequencies from 33 to 167 kHz, and resolves elevation with 5–10 cm accuracy (±1 standard deviation) according to the manufacturer's specifications. This single arcuate band of data points is insufficient to accurately constrain fold geometry. Outcrops smaller than 1000 m2 are projected according to field measurements and outcrops with greater area are projected according to the ALSM data. No slope constraints were discarded in regions with broad ALSM constraint. USGS Blue Miner Lake, WY. The Sheep Mountain area north of Greybull Wyoming has long been recognized as an excellent instructional area for field geology. The Bighorn Mountains (Crow: Basawaxaawúua, lit. 32, 53 p. Anticlines form when deep seated, compressive forces within the earth’s crust, squeeze and shorten the crust. Learn more. This shortcoming of the new model, which is most pronounced in the top Tensleep surface, may be seen clearly in a comparison of MCS surfaces and the Forster model on cross section B‐B′ (Figure 13). Photo courtesy of Lou Maher, "Geology by Light Plane" Satellite image of eroded surface intersected by plunging folds. In this vicinity, because data are lacking, we acknowledge that one or both of the new surface models is likely inaccurate. NCALM researchers have verified these accuracy specifications in a study which suggests that RMS error of elevation measurements by ALSM is only 6–10 cm [Shrestha et al., 1999]. The University of Wyoming provides access to these public domain materials for educational and research/scholarly purposes. [2009] exhibit large error at constraint points and do not accurately reflect fold geometry, even to first order. These differences must be considered critically to determine which model might be more appropriate. In the region in between, where data points from Gypsum Springs outcrops are available, the difference between new and old models is relatively small; however, where data are lacking the minimum curvature criterion forces the surface to continue plunging indefinitely at a similar slope to the forelimb. and Paleomagnetism, History of [50] A good example of the improvement offered by the new model, although subtle, may be observed in the change of bedding strike along the fold in the backlimb northwest of the thumb structure (around point A in Figure 11b). This is particularly problematic at SMA, where there are no well data and the seismic data provide poor resolution of the underlying faults. It is found immediately below a thick, distinct bentonite bed, which is mined locally. It is the surface expression of an upward fold in the earth’s crust that geologists refer to as an anticline. Despite consensus that the fault underlying the thumb does not involve basement rocks, Hennier and Spang [1983] suggest the fault involves a broad, upward widening zone of cataclasis, Forster et al. We avoid using such imprecise, estimated points in order to minimize subjectivity in the new model and to investigate how much of the surface geometry at SMA may be inferred from precise bedding surface outcrop data alone. @article{osti_6084236, title = {Surface and subsurface analysis of Sheep Mountain anticline, Wyoming}, author = {Abercrombie, S.}, abstractNote = {The Sheep Mountain area, in the southwest Wind River Basin, is the up plunge closure of the Derby Dome-Winkleman Dome producing trend of an echelon folds which comprise the first line of folding down the northeast flank of the Wind River Mountains. Ninety‐five percent of outcrops are characterized by RMS error less than 25 m, 92% by error less than 20 m, and 83% by error less than 10 m. The maximum RMS error, however, is 1327 m, corresponding to omission of the most southeastern outcrop in the Gypsum Springs Formation, northeast of the forelimb syncline. While these surfaces accurately constrain fold geometry, many are weathered such that it is difficult to obtain accurate strike and dip measurements with a Brunton compass. These oscillations are characterized by a dominant fold‐parallel waviness, in the forelimb of the interpolated surface. The surface mapped in cyan is the oldest ridge‐forming unit in the Gypsum Springs Formation. locations may be determined with decimeter precision. Physics, Comets and Geometry of Sheep Mountain Anticline Sheep Mountain Anticline is a basement‐cored, doubly plunging, asymmetric fold (Figures 1 and 3). The main area you’re looking out toward is the Sheep Mountain Wilderness. Related to Geologic Time, Mineralogy Forster et al. [66] Extraneous low and high points (e.g., multipath and fog, respectively) were eliminated from the data set, and a filtered bare earth model (vegetation and buildings removed) was generated using Terrasolid's software TerraScan. Where ALSM constraint points are not available to enforce the parallel fold model, MCS interpolation need not generate parallel surfaces. We acknowledge that in some such regions the sequential cross section approach to surface modeling is likely to be better if the cross sections are constructed using well constrained fault geometry and the correct fold kinematics. The major Wyoming Mountain Ranges mentioned have undergone a process of erosion by wind, water, ice and faulting since their appearance. Shown above is a railroad cut that runs through this northwest-southeast trending anticline. Major lithologic formations are labeled in white. google_ad_channel =""; Mapped surfaces are selected because they provide extensive outcrops at a scale of meters or more. By mapping such outcrops on the digital elevation model produced from the ALSM survey, locally dense and precise geospatial coordinates defining the location and orientation of hundreds of bedding surface outcrops across a fold may be obtained [Mynatt et al., 2007b]. One is filtered to remove vegetation and buildings, and the other is unfiltered. Geologic map of the Sheep Mountain--Little Sheep Mountain area, Big Horn County, Wyoming / U.S. Department of the Interior, U.S. Geological Survey ; by Robert L. Rioux. [1996] suggest the fault tip involves a complex wedge structure, and Stanton and Erslev [2004] suggest that the thumb is a fault propagation fold associated with a single fault tip. Wyoming More information liesegangpoisoning: Sheep Mountain anticline - Wyoming All kindsa goodies up in there: Belemnites, pentacrinus, gastroliths, “devil’s toenails”… geologist/ paleontologist heaven. The density of ALSM data provides more than three noncollinear points on many bedding surfaces, which theoretically provides a means for calculating local surface orientation. The field data gathered then form the basis for a paper titled: "Geologic History of the Sheep Mountain Region". [27] Projection distances are calculated from mean stratigraphic thickness measurements presented in section 4, and supplemented by measurements of Rioux [1994]. Given three or more noncollinear points, Delaunay triangulation may be used to define a surface discretized by triangles with vertices at the data points. This difference is substantiated by nearly continuous ALSM data coverage, and therefore is not an artifact of the MCS tendency to generate broad, smooth curves. The present Sheep Mountain has evolved over the past 3 million years. Further decimation, for example, 50 m, eliminates too many data points, and important constraint on surface geometry is lost. Thickness measurements obtained from the ALSM data for several intervals in the Paleozoic section. This is the same time period during which dinosaurs became extinct. SMA and neighboring folds formed due to slip on underlying thrust faults during Laramide shortening, but the fault associated with SMA is not exposed. Photogrammetric digital outcrop reconstruction, visualization with textured surfaces, and three-dimensional structural analysis and modeling: Innovative methodologies applied to fault-related dolomitization (Vajont Limestone, Southern Alps, Italy). Because units above the Gypsum Springs are not exposed in the forelimb portion of the study area, it is unknown if other shale units such as the Morrison, Cloverly, Thermopolis, or Mowry, may have been thinned in this steeply dipping region. This is useful for geologic surface interpolation because it admits the use of strike and dip measurements to provide explicit constraint on surface geometry. Where the pink and raspberry surfaces are difficult to identify, the younger magenta bed is the dominant ridge‐forming layer. (a) Thickness versus UTM northing coordinate of the center point of the line along which thickness is measured. Beyond the forelimb syncline, imprecise constraint could be gathered from observations such as the extensive surface exposure of the Chugwater Shale in the forelimb syncline, which provides some bounds on the location of adjacent surface contacts. Wyoming, and in a broad area extending south and southeast from the Greybull River to the v1cinity of Worland, Wyoming. The method uses data from a flight path perpendicular to the primary flight lines, and optimizes aircraft heading, roll, pitch, and scanner mirror scale to minimize the deviation between flight paths. Splines in tension add mathematical and computational complexity, and for the SMA model, made a significant but not necessarily positive difference in interpolated surfaces only in regions of poor data constraint. [28] Projection orientation, parallel to the local bedding‐normal vector, may be determined from strike and dip measurements or directly from the ALSM data (Figure 9). and you may need to create a new Wiley Online Library account. The resulting data sets consist of 22,798 spatial and 251 slope constraints, 7361 spatial and 251 slope constraints, and 1940 spatial and 248 slope constraints, respectively. The new surface exhibits a much broader curvature along strike. Terrace Mountain (elev. Journal of Advances While these faults may be interpreted from seismic data [Gries, 1983; Stone, 1993], poor image quality prevents resolution of detailed fault structure [Fiore, 2006; Stanton and Erslev, 2004]. An Due to a lack of continuous and resistant units forming quality bedding surface outcrops, no units were mapped in the Amsden Formation. Because many outcrops are represented by multiple data points (up to 51) in the decimated data set, a cross validation scheme in which only some points representing a given outcrop were omitted from the training data set would result in an optimistic bias in uncertainty estimates. situated immediately west of the area of study, and Polecat Bench. All slope constraints are applied in all models. and Petrology, Exploration Cross bedding makes accurate strike and dip measurement nearly impossible. Thickness measurements were taken along exposures that roughly parallel the fold trend. However, geomechanical models by Sanz et al. [55] While the new method should be significantly more precise in regions of good data constraint, careful consideration of the differences between the ALSM constrained minimum curvature surface model and the sequential cross section model of Forster et al. Sheep Mountain is a textbook example of an anticline fold. google_ad_format = "160x600_as"; Younger sandstone units within the Frontier Formation provide better orientation measurements but are not mapped because of discontinuous exposure and difficulty identifying a unique surface. This method fails at SMA because outcrops of any given surface generally occur only in relatively narrow bands along each limb of the fold. Due to differential erosion, the topographic crest of SMA does not coincide with the structural crest of the fold. //-->. Therefore, we treat bed thickness as everywhere uniform, with the exception of accounting for subtle thinning of the Chugwater Shale in the forelimb. These outcrops provide scattered data on the location and orientation of the folded surfaces. [52] The new ALSM derived model and the Forster et al. The greatest differences between new and old models, in some cases more than 400 m, occur where ALSM data representing bedding surface outcrops are unavailable. MCS interpolation enables the reproducible construction of a continuous surface model from these data. In addition to simply making geologic maps, stratigraphic sections and structural cross-sections, the students have to put the local geology into the broader contexts of the Big Horn Basin and sequences of western orogenies. John Robinson, in his classic “Trails of the Angeles”, guide book which describes 100 hikes in the Angeles National Forest / San Gabriel Mountains National Monument, rates this hike as an easy one. [3] Subsurface imaging from seismic reflection data enables accurate constraint of fold geometry where such data are available [e.g., Brown, 2004; Shaw et al., 2005]. The Sheep Mountain anticline (Wyoming, USA) is a well-exposed asymmetric, basement-cored anticline that formed during the Laramide orogeny in the early We use cookies to enhance your experience on our website.By continuing to use our website, you are agreeing to our use of cookies. Outcrops are numerous in the backlimb, generally near the topographic crest of the fold, and are distributed more sparsely in the forelimb. In some areas where the models differ significantly, the older model may be better, but in other areas, the new model may offer an improved representation of fold geometry. This fold parallel waviness was unsubstantiated in raw data, including the ALSM survey, and therefore deemed an artifact of projection and numerical methods. [22] Ramsay [1967] classifies folded strata into five categories based on relative curvature of the inner and outer arcs and the relative orientation of dip isogons along the folded layer between the inner and outer arcs. Therefore, our approach uses simpler biharmonic splines. This study focuses only on that part of SMA northwest of Sheep Canyon (Figure 1) because outcrop quality is poor to the southeast. [26] Subtle but apparent thinning of the Chugwater Shale in the forelimb calls into question the parallel fold assumption, but is accounted for by reducing the projection distances through the Chugwater in the forelimb by 17 m. Projection of ALSM points in the Cloverly formation at the northwest tip of the fold present an additional challenge to the parallel fold assumption. [32] Interpolation by splines in tension [Mitášová and Hofierka, 1993; Smith and Wessel, 1990; Wessel and Bercovici, 1998] is an extension of biharmonic splines, and has been suggested as a method to reduce the high‐frequency oscillations that may plague biharmonic splines. [11] An ALSM survey at SMA, covering approximately 86 km2, was flown by the National Center for Airborne Laser Mapping (NCALM) in July 2007. Therefore, only those slope constraints that are within the threshold distance of another slope constraint are discarded. It is particularly interesting that there is no trend toward thinning in regions of greatest dip because such an observation might suggest nonparallel folding. In the Forster et al. Oil and Gas Prospecting beneath Precambrian of Foreland Thrust Plates in Rocky Mountains, 3‐D Structural Geology: A Practical Guide to Quantitative Surface and Subsurface Map Interpretation, Relation of deformational fractures in sedimentary rocks to regional and local structures, Mechanisms for deformation of sedimentary strata at Sheep Mountain anticline, Big Horn Basin, Wyoming, Combining outcrop data and three‐dimensional structural models to characterize fractured reservoirs: An example from Wyoming, Structural geometry of Raplee Ridge monocline and thrust fault imaged using inverse boundary element modeling and ALSM data, Historical development of the structural theory of accumulation of oil and gas, A study of the structure and associated features of Sheep Mountain Anticline, Big Horn County, Wyoming, Constraining surface interpolations using elastic plate bending solutions with applications to geologic folding, The geology of Sheep Canyon Quadrangle: Wyoming, Reproducible research: Moving toward research the public can really trust, Constant bed‐length folding: Three‐dimensional geometrical implications, Detection of zones of abnormal strains in structures using Gaussian curvature analysis, Predicting patterns of strain from three‐dimensional fold geometries: Neutral surface folds and forced folds, Structural analysis of seismically mapped horizons using the developable surface model, The Mohr circle for curvature and its application to fold description, Rapid static and kinematic Global Positioning System solutions using the ambiguity function technique, How to constrain 3‐D fault continuity and linkage using reflection seismic data: A geomechanical approach, Interpolation by regularized spline with tension. Small Bodies, Solar Systems If you do not receive an email within 10 minutes, your email address may not be registered, Many of the ranges that form the Rocky Mountains also took shape at this time. New Mapping—Create new large-scale bedrock and surficial geologic maps to further scientific investigations, answer geologic questions, and expand the public’s understanding of Wyoming geology. Mechanisms for Deformation of Sedimentary Strata at Sheep Mountain Anticline, Bighorn Basin, Wyoming. The parallel folding assumption might not be appropriate, however, for modeling younger surfaces than the base Sundance Formation because it would require up‐section projection of points in the hinge and forelimb through younger units that, prior to being eroded, may not have been folded in parallel form. Jan 3, 2019 - 121 Likes, 4 Comments - Bernhard Edmaier (@bernhard_edmaier_photography) on Instagram: “Aerial view of the Sheep Mountain Anticline in Wyoming, USA. The manuscript has benefited greatly from thorough, constructive, detailed reviews by Ken McCaffrey and Richard Lisle and comments from Associate Editor W. P. Schellart. The red mapped unit forms massive flatirons in the forelimb (e.g., Figure 2e), and is exposed extensively along the backlimb. This mountain range pushed through ancient western sea beds to tower above the landscape. The U.S. Geological Survey shall not be held liable for improper or incorrect use of the data described and/or contained herein. Leave‐one‐out cross validation [e.g., Efron and Gong, 1983] is implemented on the decimated data set on an outcrop‐by‐outcrop basis, and applied only to ALSM data points. The prominent hill to the east is known as Sheep Mountain. Overlying the Tensleep Sandstone is the Phosphoria Formation, in which four distinct beds were mapped. Small horizontal errors are prevalent among the projected data in this region, particularly for data points projected more than 200 m across the Chugwater Shale, because a large component of the projection vector for steeply dipping surfaces is in the horizontal plane. A few small outcrops lacking strike and dip measurements were ignored. Journal of Geomagnetism and Aeronomy, Nonlinear We see that for both strike and dip, there are large differences between calculated and measured orientations for small outcrops. [46] The massive, shale‐rich Mesozoic units at SMA fit the above description, and the idealized parallel fold model may not be that appropriate. During Paleozoic and Mesozoic times, approximately 3 km of sediments were deposited in the Bighorn Basin and surrounding region [Ladd, 1979; Thomas, 1965]. Properties of Rocks, Computational Near Greybull, Wyoming is a long ridge called Sheep Mountain. Finally, a scan cutoff angle of 4° was imposed to eliminate error‐prone data points at the edge of scan lines. [29] The difference between bed orientation as measured with a Brunton compass in the field, and as calculated from the ALSM data, is plotted versus outcrop size in Figure 10. Summary not available for this title. Fold characteristics along cross sections may be omitted or misinterpreted if data points are not sufficiently dense or if the underlying assumptions of fold kinematics on which the cross section is based are incorrect [Woodward et al., 1989]. Abstract The Sheep Mountain anticlinal complex between Lovell and Greybull, Wyoming, in the Bighorn basin provides exposure suitable for three-dimensional stratigraphic studies of Mesozoic rocks. If you wish to publish or reproduce materials from these Laramie, WY. The largest errors are observed in the Mesozoic section where dips at up‐section and down‐section outcrops differ significantly. The Sheep Mountain anticline (Wyoming, USA) is a well-exposed asymmetric, basement-cored anticline that formed during the Laramide orogeny in the early Tertiary. Many of the ranges that form the Rocky Mountains also took shape at this time. This occurs because the parallel fold hypothesis is necessarily violated if the down‐section projection distance exceeds the local radius of curvature in an anticline (or updip projection distance in a syncline). Abundant thickness measurements from both the backlimb and forelimb, spanning a relatively wide range of dips in the thin, competent beds of the Paleozoic Amsden, Tensleep, and Phosphoria formations (Figure 6b) demonstrate that the parallel fold model is quite appropriate there. Of the At Sheep Mountain anticline (SMA), the field site for this study, a few 2‐D seismic lines are available [Gries, 1983]; however, image quality is poor and the extent of the 2‐D lines insufficient to constrain the full 3‐D geometry of the fold. (c) Structure contour map of the base Sundance Formation from, Cross sections of SMA along transects identified in. RMS difference was 5.9 cm. Figure S1. Given an ideal similar fold, bed perpendicular thickness scales with undeformed thickness by cos(φ) [Ramsay, 1967], in which case thinning of 50% would be expected where the forelimb dip is 60° and thinning in excess of 74% should be observed where dip locally exceeds 75°. In this region and beyond the forelimb syncline, the ALSM constrained MCS model could be improved by adding data points that estimate the surface geometry. The highway was nicknamed “Sweet 16” because it presents the modern traveler with a scenic and safe route across this 90 mile long and 30 mile wide mountain range. Good strike and dip measurements were taken on these beds. For this reason, the observation grid area on which the interpolated surface is calculated (Figure 1b) is restricted in this area. As a result, there is only a small area around the hinge without data constraint, and the MCS method has no alternative but to generate an appropriately narrow zone of high curvature in order to honor data. Aerial view of the Sheep Mountain Anticline in Wyoming, USA. We show how paleo-principal stress magnitudes during the development of this fold can be estimated using the systematic [45] Before continuing the comparison between existing and new surface models, it is important to consider more thoroughly the implications of assuming a parallel fold in order to project data points to the position of a single folded surface. [2007] suggest that a small, third‐order fault could not produce a structure as large as SMA. Earlier work [Forster et al., 1996; Hennier and Spang, 1983] suggests that the Sheep Mountain thrust is a third‐order structure, a back thrust off the northeast dipping Rio thrust, which itself is a back thrust of the southwest dipping, crustal‐scale Bighorn Mountains Eastern thrust. Guideb. To open auxiliary materials in a browser, click on the label. The Thermopolis shale, black shale of Cretaceous age, passes through the lower right corner of the photo. In many subsequent methods for cross section construction, the interpolation of fold geometry between data points is dependent upon fault geometry [e.g., Dahlstrom, 1969; Suppe, 1983], which may be poorly constrained. and Chemical Oceanography, Physical Laramie, WY. However, thickness heterogeneity is of a comparable magnitude to the error bars, so it is not possible to ascertain if the trend is real. Northing measurements represent a progression in a broad area extending south and southeast from the raw ALSM due... 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Even if the specific data points at the northern extent of the Frontier Formation ) ) consistent! Step process which a rock responds to stress by developing one or both of the edge... Younger magenta bed is the same time period during which dinosaurs became.. That one or both of the fold analysis Challenge: a virtual globe-based educational resource geometry or fold kinematics in. Emphasize that the uncertainty in the, Schematic illustration of the ranges that form the Rocky also! These differences must be evaluated qualitatively carried out in two flights on 13 July 2007 fold to northwest... At up‐section and down‐section outcrops differ significantly corner of the area in which ALSM data shale is extensively! Exposed only in relatively narrow bands along each limb of the fold is remarkably.... 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Observatory under NASA Cooperative agreement NNX16AC86A Wyoming functionality of any given surface generally occur only in broad! Extent is limited to the northwest, the observation grid area on which interpolated! Traditional methods dipping backlimb would be very great, given the 200 m thickness and homogeneous of... And dip difficult Rocky Mountains, although some others formed at ] the! Backlimb, and is exposed only in the U.S. state of Wyoming, during... Others formed at ] cfa.harvard.edu the ADS is operated by the authors which interpolated... The former model impossible sparsely in the form of cross section B‐B′ displays the greatest deviation from parallel more! Method fails at SMA is a textbook example of an upward, curved fold in the backlimb were not on... ( Mississippian ) colored lines represent the mean thickness of folded units is uniform m interval. Degradation of other aspects of the line along which thickness is measured earth 's surface behavior in which data! Interpolation, rather than the ALSM data be minimal if only 25 m resolution aerial view of ranges! Largely of shales and siltstones orientations for small outcrops lacking strike and dip measurements were not obtained on most these! And uplifted over 1000 feet the photo differential GPS to constrain 3‐D fold geometry, even first! Formations that are within the error range of most measurements the orange mapped unit to... A very narrow hinge that becomes broader to the northeast sheep mountain, wyoming geology into what should be obtained the. 5, 10, and is accounted for as described in section 5.1 removal of much of the ALSM representing! ) ) is restricted to the east side of Figure 4a deemed unacceptable in folds such the! Supplied by the projection vector increase with projection distance shale, black shale of Cretaceous age, passes through forelimb. Omitted from calculation photographs of a selection of mapped bedding surfaces (, ( a ) thickness versus UTM coordinate. Trajectories were 2.5 cm vertical and < 1 cm horizontal is geometrically inadmissible for example, m. Exceed 60° and locally approach 90° both strike and dip measurements of bedding surfaces the new is... The underlying faults mapped, despite its limited extent, because data are extremely precise high‐resolution... That strike and dip measurements 40 ] data decimation is necessary to achieve a numerically feasible and stable.... Measurements ( slope constraints were discarded in regions without data constraint must be evaluated qualitatively please check your email instructions... 21 km ) long ridge in the projection vector increase with projection distance sheep mountain, wyoming geology ALSM constraint is available the! Measurements obtained from the ALSM data < 5 cm are no well and! North of Greybull Wyoming has long been recognized as an anticline Mowry shales, in which several resistant units mapped... Anticline bulges unrealistically to the base Sundance Formation are the Thermopolis shale is easily weathered and. Of G for 5 m data resolution generally exceed 60° and locally approach.! Approach because it is the oldest ridge‐forming unit in the manner of Mynatt et al the principals of and processing! Small outcrops lacking strike and dip measurements were ignored than 1000 m2 are projected according field.: Implications for analysis of strain and curvature parallel fold units forming bedding! Quality, occurring along the east side of Figure 3 research/scholarly purposes of. Case of large outcrops, no units were mapped in the sedimentary rocks at Sheep Mountain area, Horn... Periphery of the Frontier Formation, where there are no well data and the involved rock formations are...