It is particularly interesting that there is no trend toward thinning in regions of greatest dip because such an observation might suggest nonparallel folding. The University of Wyoming provides access to these public domain materials for educational and research/scholarly purposes. 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. Much of the difference between models in areas of dense data coverage may be attributed to increased resolution and accuracy of the ALSM constrained MCS method. . 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. google_ad_width = 160; In areas of active mining, this surface provides excellent sites for strike and dip measurement; however, good, unweathered exposures elsewhere are limited. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. In regions without outcrops of bedding surfaces the new and old surface models can differ by hundreds of meters. The oldest sedimentary units exposed at SMA are found in the core of the fold, near the hinge, and form the topographic high that is Sheep Mountain. 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. [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. Structural Geology: A Quantitative Introduction. Units mapped higher in the stratigraphic column are exposed only in the backlimb. In regions of good data coverage, the difference is smaller, generally less than the 40 m contour interval. Geological Map of Sheep Mountain As a take-home assignment worth 4% of your final mark, create a hand-drawn geological map of the northern part of Sheep Mountain in Wyoming. The studied outcrop is Sheep Mountain, an asymmetric basement cored anticline corresponding to a typical Laramide arch of the Bighorn Basin (Wyoming, USA). [54] Large negative differences are apparent on the contours of Figure 12 in portions of the backlimb (e.g., points E and F in Figure 11b, cross section E‐E′ in Figure 13) where dips are greater in the ALSM model than in the older model. [4] Early methods for constructing cross sections of folded strata, such as the Busk method [Busk, 1929], in which folded surfaces are interpreted as concentric circular arcs, rely upon simple geometric relations to interpolate fold surfaces between sparse data points. [2007] use differential GPS to constrain the geometry of small folds and small patches of larger folds. The steeply dipping forelimb faces northeast and dips generally exceed 60° and locally approach 90°. A high‐resolution version of this map is available in the, Schematic illustration of the stratigraphic thickness calculation (. Cross validation is implemented on an outcrop‐by‐outcrop, rather than point‐by‐point, basis in order to minimize the bias of the resulting measure of model uncertainty. [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. 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