We thank Erin Bradley and Liz Cole for their assistance in the field. Field work, thin-section preparation and material for the sandbox model was supported by Franklin &amp; Marshall College's Committee on Grants.

1. Collection of Macroscale Field Data
<ol>
	<li>Before conducting field work, use aerial photographs/topographic maps to identify the overall trend of the mountains (defined by the modern-day ridge crest), transverse zones, faults and other lineations at the macroscale (Figure 2).
	<ol>
		<li>Use similar scale topographic maps and aerial photographs, so that patterns can be directly compared. Use 1:24,000 scale maps and photographs.</li>
	</ol>
	</li>
	<li>Label and highlight macroscale features on th...

<ol>
	<li>Marshak, S., Wilkerson, M. S., Hsui, H. T., KR, M. c. C. l. a. y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Generation+of+curved+fold-thrust+belts:+Insights+from+simple+physical+and+analytical.">Generation of curved fold-thrust belts: Insights from simple physical and analytical.</a> modelsThrust Tectonics. , 83-92 (1992).</li><li>Mitra, G., S, S. e. n. g. u. p. t. a. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evolution+of+salients+in+a+fold-and-thrust+belt:+the+effects+of+sedimentary+basin+geometry,+strain+distribution+and+critical+taper.">Evolution of salients in a fold-and-thrust belt: the effects of sedimentary basin geometry, strain distribution and critical taper.</a> Evolution of Geological Structures in Micro- to Macro-scales. , 59-90 (1997).</li><li>Weil, A., Sussman, A., A, S. u. s. s. m. a. n., A, W. e. i. l. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Classifying+curved+orogens+based+on+timing+relationships+between+structural+development+and+vertical+axis+rotations.">Classifying curved orogens based on timing relationships between structural development and vertical axis rotations.</a> Orogenic curvature Geol. Soc. of Am. Special Paper. 383, 205-223 (2004).</li><li>Ismat, Z., Mitra, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Folding+by+cataclastic+flow+at+shallow+crustal+levels+in+the+Canyon+Range,+Sevier+orogenic+belt,+west-Central+Utah.">Folding by cataclastic flow at shallow crustal levels in the Canyon Range, Sevier orogenic belt, west-Central Utah.</a> J. of Struct. Geol. 23 (2-3), 355-378 (2001).</li><li>Tull, J., Holm, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structural+evolution+of+a+major+Appalachian+salient-recess+junction:+Consequences+of+oblique+collisional+convergence+across+a+continental+margin+transform+fault.">Structural evolution of a major Appalachian salient-recess junction: Consequences of oblique collisional convergence across a continental margin transform fault.</a> Geol. Soc. of Am. Bull. 117 (3), 482-499 (2005).</li><li>Ismat, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Block+supported+cataclastic+flow+within+the+upper+crust.">Block supported cataclastic flow within the upper crust.</a> J. of Struct. Geol. 56, 118-128 (2013).</li><li>Ismat, Z., Toeneboehn, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Deformation+along+a+salient-transverse+zone+junction:+An+example+from+the+Leamington+transverse+zone,Utah,+Sevier+fold-thrust+belt+(USA).">Deformation along a salient-transverse zone junction: An example from the Leamington transverse zone,Utah, Sevier fold-thrust belt (USA).</a> J. of Struct. Geol. 75, 60-79 (2015).</li><li>Reed, F. S., Mergner, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preparation+of+Rock+Thin+Sections.">Preparation of Rock Thin Sections.</a> Amer. Mineral. 38, 1184-1203 (1953).</li><li>Underwood, E. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Quantitative Stereology. , (1970).</li><li>Fry, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Random+point+distribution+and+strain+measurement+in+rock.">Random point distribution and strain measurement in rock.</a> Tectonophys. 60 (1), 89-105 (1979).</li><li>McNaught, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Estimating+uncertainty+in+normalized+Fry+plots+using+a+bootstrap+approach.">Estimating uncertainty in normalized Fry plots using a bootstrap approach.</a> J. of Struct. Geol. 24 (2), 311-322 (2002).</li><li>De Paor, D. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+Interactive+Program+for+Doing+Fry+Strain+Analysis+on+the+Macintosh+Microcomputer.">An Interactive Program for Doing Fry Strain Analysis on the Macintosh Microcomputer.</a> J. of Geol. Ed. 37 (3), 171-180 (1989).</li><li>Ismat, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Folding+kinematics+expressed+in+fracture+patterns:+An+example+from+the+Anti-Atlas+fold-belt,+Morocco.">Folding kinematics expressed in fracture patterns: An example from the Anti-Atlas fold-belt, Morocco.</a> J. of Struct. Geol. 30 (11), 1396-1404 (2008).</li><li>Reches, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Faulting+of+rocks+in+three-dimensional+strain+fields:+II.+Theoretical+analysis.">Faulting of rocks in three-dimensional strain fields: II. Theoretical analysis.</a> Tectonophys. 95 (1-2), 133-156 (1983).</li><li>Reches, Z., Dieterich, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Faulting+of+rocks+in+three+dimensional+strain+fields:+1.+Failure+of+rocks+in+polyaxial,+servo-control+experiments.">Faulting of rocks in three dimensional strain fields: 1. Failure of rocks in polyaxial, servo-control experiments.</a> Tectonophys. 95 (1-2), 111-132 (1983).</li><li>Ismat, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evolution+of+fracture+porosity+and+permeability+during+folding+by+cataclastic+flow:+Implications+for+syntectonic+fluid+flow.">Evolution of fracture porosity and permeability during folding by cataclastic flow: Implications for syntectonic fluid flow.</a> Rocky Mount. Geol. 47 (2), 133-155 (2012).</li><li>Kwon, S., Mitra, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Three-dimensional+kinematic+history+at+an+oblique+ramp,+Leamington+zone,+Sevier+belt,+Utah.">Three-dimensional kinematic history at an oblique ramp, Leamington zone, Sevier belt, Utah.</a> J. of Struct. Geol. 28 (3), 474-493 (2006).</li><li>Casas, A. M., Simon, J. L., Seron, F. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stress+deflection+in+a+tectonic+compressional+field:+A+model+for+the+northeastern+Iberian+chain,+Spain.">Stress deflection in a tectonic compressional field: A model for the northeastern Iberian chain, Spain.</a> J. of Geophys. Res. 97, 7183-7192 (1992).</li><li>Apotria, T. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thrust+sheet+rotation+and+out-of-plane+strains+associated+with+oblique+ramps:+An+example.">Thrust sheet rotation and out-of-plane strains associated with oblique ramps: An example.</a> J. of Struct. Geol. 17 (5), 647-662 (1995).</li><li>Hubbert, M. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Theory+of+Scale+Models+as+Applied+to+the+Study+of+Geological+Structures.">Theory of Scale Models as Applied to the Study of Geological Structures.</a> Geol. Soc. of Am. Bull. 48 (10), 1459-1520 (1937).</li><li>Sch&#246;pfen, M. P. J., Steyrer, H. P., Koyi, H. A., Mancktelow, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experimental+modeling+of+strike-slip+faults+and+the+self-similar+behavior.">Experimental modeling of strike-slip faults and the self-similar behavior.</a> Tectonic Modeling: A volume in honor of Hans Ramberg Geol. Soc. of Am. Mem. 193, 21-27 (2001).</li><li>Kwon, S., Mitra, G., Sussman, A., Weil, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Strain+distribution,+strain+history+and+kinematic+evolution+associated+with+the+formation+of+arcuate+salients+in+fold-thrust+belts:+the+example+of+the+Provo+salient,+Sevier+orogeny,+Utah.">Strain distribution, strain history and kinematic evolution associated with the formation of arcuate salients in fold-thrust belts: the example of the Provo salient, Sevier orogeny, Utah.</a> Orogenic curvature Geol. Soc. of Am. Special Paper. 383, 205-223 (2004).</li><li>Elliott, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+motion+of+thrust+sheets.">The motion of thrust sheets.</a> J. of Geophys. Res. 81, 949-963 (1976).</li></ol>

The authors have nothing to disclose.

The Central Utah segment of the Sevier fold-thrust belt, and its northern boundary, the Leamington transverse zone serves as an ideal natural laboratory for studying salient-recess junctions (Figure 1). Along this junction, the transport direction remains constant and the thrust sheets are uninterrupted across the junction, so the only variable is the underlying basement geometry5.
Here, we present a method to analyze this type of salient-recess junction by combinin...

Fold-thrust belts are composed of salients (or segments), where the thrust sheets in adjoining salients are decoupled by recesses or transverse zones1,2,3. The transition from salient to recess may be markedly complex, involving a multifaceted suite of structures, and may hold critical clues to fold-thrust belt development. In this paper, we carefully examine a salient-recess junction, using a combination of multiscale field data and a sandbox model, in order to better understand how deformation can be accommodated within fold-thrust belts.
The junction of the Central Utah segment and the Leamington transverse zone is an ideal natural-laboratory for studying salient-recess junctions for several reasons (Figure 1). First, the rocks exposed within the segment continue, uninterrupted, into the transverse zone4. So, deformation patterns can be tracked continuously, and compared across the junction. Second, the rocks are essentially monomineralic, so variation in fault patterns are not a result of heterogeneities within units, but instead reflect the overall folding and thrusting within the study area4. Third, elastico-frictional mechanisms, such as cataclastic flow, assisted deformation throughout the field area, allowing for direct comparisons of mesoscale fault patterns4. Finally, the overall transport direction remained continuous along the length of the segment and transverse zone; therefore, variations in shortening direction did not influence the preserved deformation patterns4. All of these factors minimize the number of variables that may have affected the deformation along the segment and transverse zone. As a result, we surmise that the preserved structures formed primarily because of a change in the underlying basement geometry5.
<img alt="Figure 3" src="/files/ftp_upload/54318/54318fig1.jpg" /> 
Figure 1. Example of index map. The Sevier fold-thrust belt of western USA, showing major salients, segments, recesses and transverse zones. Figure 2 indicated by boxed area (modified from Ismat and Toeneboehn7). <a href="https://www.jove.com/files/ftp_upload/54318/54318fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
Folding and thrusting within the Central Utah segment and Leamington transverse zone, took place at depths &#60; 15 km, i.e., within the elastico-frictional regime, where deformation occurred primarily by outcrop-scale (&#60; 1 m) faults and cataclastic flow4,6. Because transport and folding of the thrust sheet took place primarily by elastico-frictional mechanisms, we predict that a detailed fault analysis can provide further insight into the kinematic history of the Leamington transverse zone and the underlying basement geometry. In order to test this hypothesis, we have collected and analyzed fault patterns preserved in the rocks within the northern portion of the Central Utah segment and throughout the Leamington transverse zone (Figure 2).
<img alt="Figure 3" src="/files/ftp_upload/54318/54318fig2.jpg" /> 
Figure 2. Example of macroscale topographic map. Shaded-relief topographic map of boxed area in Figure 1. The 4 Regions are separated by solid white lines. Bedding contacts between the Proterozoic Caddy Canyon quartzite (PCc), Proterozoic Mutual quartzite (PCm) and Cambrian Tintic quartzite (Ct) are shown. Dashed lines show the trend of the mountains within this area. Site locations are shown with numbered black squares. First-order lineations are shown with solid gray lines (modified from Ismat and Toeneboehn7). <a href="https://www.jove.com/files/ftp_upload/54318/54318fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
Sandbox experiments were carried out to compare against, and supplement, the fault data. A push-block sandbox model, with frontal and oblique ramps, was used to assist our analyses of the structures preserved in, and around, the Leamington transverse zone (Figure 3) 7. The objectives of this approach are four-fold: 1) determine if the mesoscale fault patterns are consistent, 2) determine if the sandbox model supports and explains the field data, 3) determine if the sandbox model provides more details on structures that are not observed in the field, and 4) evaluate whether this combined field-experimental method is useful and easy to replicate.
<img alt="Figure 3" src="/files/ftp_upload/54318/54318fig3.jpg" /> 
Figure 3. Example of push-block model. Photograph of empty sandbox model. The southern frontal ramp (SFR), oblique ramp (OR), northern frontal ramp (NFR), and the four Regions (1-4) are labeled (modified from Ismat and Toeneboehn7). <a href="https://www.jove.com/files/ftp_upload/54318/54318fig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

<table border="0" cellpadding="0" cellspacing="0" width="1362">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:227px;">fiberboard</td>
			<td style="width:140px;">Any</td>
			<td style="width:195px;">NA</td>
			<td style="width:800px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">finishing lacquer</td>
			<td>Any</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">epoxy</td>
			<td>Epoxy technology</td>
			<td>Parts A and B: 301-2 2LB</td>
			<td>best if warmed to 80&#186; - 125&#186;. If warming is not possible, it will cure fine, it will just take 1 week, rather than 1 day.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">ramp wood-pine</td>
			<td>Any</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">painters tape</td>
			<td>Any</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">rabbit joints</td>
			<td>Any</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">countersunk fasteners</td>
			<td>Any</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">sand paper</td>
			<td>Any</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">play sand</td>
			<td>Any</td>
			<td>NA</td>
			<td>best if homogenous grain size, ~0.5mm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">food coloring</td>
			<td>Any</td>
			<td>NA</td>
			<td>best to use one color and a dark color</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">plastic mesh/grid</td>
			<td>Any</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">square cross oins</td>
			<td>Any</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">crank screw</td>
			<td>Any</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">crank handle</td>
			<td>Any</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">sheet metal</td>
			<td>Any</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">dividers bars</td>
			<td>Any</td>
			<td>NA</td>
			<td></td>
		</tr>
	</tbody>
</table>

kinematic history of a salient-recess junction explored through a combined approach of field data and analog sandbox modeling

Within fold-thrust belts, the junctions between salients and recesses may hold critical clues to the overall kinematic history. The deformation history within these junctions is best preserved in areas where thrust sheets extend from a salient through an adjacent recess. We examine one such junction within the Sevier fold-thrust belt (western United States) along the Leamington transverse zone, northern Utah. Deformation within this junction took place by faulting and cataclastic flow. Here, we describe a protocol that examines these fault patterns to better understand the kinematic history of the field area. Fault data is supplemented by analog sandbox experiments. This study suggests that, in detail, deformation within the overlying thrust sheet may not directly reflect the underlying basement structure. We demonstrate that this combined field-experimental approach is easy, accessible, and may provide more details to the deformation preserved in the crust than other more expensive methods, such as computer modeling. In addition, the sandbox model may help to explain why and how these details formed. This method can be applied throughout fold-thrust belts, where upper-crustal rocks are well preserved. In addition, it can be modified to study any part of the upper crust that has been deformed via elastico-frictional mechanisms. Finally, this combined approach may provide more details as to how fold-thrust belts maintain critical-taper and serve as potential targets for natural resource exploration.

Aerial photographs were used to subdivide the field area into four Regions (1-4), based on the trend of the modern mountain ridge crest (Figure 2). Multi-scale fault data is compared between these four Regions. Assuming that these trend changes reflect the underlying basement geometry, the oblique ramp is positioned within Regions 2 and 3, where the mountains trend oblique to the Sevier fold-thrust belt. Throughout the four Regions, we found that the mesoscale faults pres...

Watch this Scientific Journal Video about Kinematic History of a Salient-recess Junction Explored through a Combined Approach of Field Data and Analog Sandbox Modeling at JoVE.com

Kinematic History of a Salient-recess Junction Explored through a Combined Approach of Field Data and Analog Sandbox Modeling

Kinematic histories of fold-thrust belts are typically based on careful examinations of high-grade metamorphic rocks within a salient. We provide a novel method of understanding fold-thrust belts by examining salient-recess junctions. We analyze the oft-ignored upper crustal rocks using a combined approach of detailed fault analysis with experimental sandbox modeling.

Within fold-thrust belts, the junctions between salients and recesses may hold critical clues to the overall kinematic history. The deformation history ...

The overall goal of this experiment is to track the deformation of thrust sheets as they move over oblique ramps. This method can help answer key questions in the field, such as how thrust sheets evolve in complex settings. The main advantages of this technique are that it is simple, inexpensive, and can be compared directly to the field data.This video shows how to use a push-block sandbox to replicate micro-scale faults found in the field. Field identification of micro-scale faults is covered in the text protocol, as is the general construction of the sandbox. To load the sandbox, use standard play sand, which is relatively homogeneous, with an average grain size of 5 milimeters.Prepare the sand by dying half of it. First, fill a 5 gallon bucket a quarter full. Then mix in enough black food coloring to make the sand a uniform dark green, which is easily distinguishable from the sand's original color.Upon drying the sand, as described in the text protocol, load the box with alternating layers of colored and uncolored sand, and ensure that each layer's leveled after it is added. The thicknesses of the sand pack that provides the clearest and most reproducible results should be arrived at empirically. This example shows a 3.5 centimeter sand pack with alternating colors every 6 centimeters.Next, gently press a plastic mesh composed of half inch of half inch squares onto the sand to produce a grid indentation. Then, insert square cross pins two inches apart throughout the sand. Next, mount a camera to view the entire sandbox.Now, push the sand with the crank-driven push-block to recreate shortening seen in the field. Move the push-block slowly enough that changes in the sand can be carefully documented. The speed should not affect the results.While pushing the sand, track the deformation by observing the shape changes of the squares, and track the amount of transport and vertical rotation by observing the motion of the pins. Repeat this process until the formed structures resemble those preserved in nature. Once the sandbox results mimic those preserved in nature, collect sample data.First, remove all cross pins from the sand. Then, to make samples, separate in epoxy portions of the deformed sand. This requires pre-cut sheet metal dividers.The bottom edge of the dividers must be made to match the angle of the ramp where the sample is to be taken and must fully extend the length of the ramp. The divider must also be taller than the sand pack. Before using a divider, cover it with painter's tape for easy cleanup.One end of the divider must be closer to control the flow of the epoxy, and the other end of the divider must be open to minimized disturbances to the sand pack. Next, fasten the divider using 1/4 inch by four inch screws, sheets with 3/8 inch diameter aluminum tubing. In this case, two dividers are used.One is placed on the oblique ramp, the other covers the frontal oblique ramp junction. Now, pour warm epoxy over the sand within the divider until no more epoxy can be absorbed, so the sand is fully saturated and will not come apart. After several days of drying, slide the dividers out of the sandbox, then lift the epoxied samples out from the surrounding sand.Using a rock saw, cut the samples perpendicularly and parallel to the strike of the ramps. Then, using permanent marker, highlight the bedding, folds, and faults within the exposed slices. A field study found four adjacent regions, each with mesoscale faults.The faults preserve a deformation fabric, which was penetrative and homogeneous at the mesoscale. The fault patterns were also unique within each region, which supported the macroscale assumption that an oblique ramp underlies regions two and three, and suggested that the conjugate-conjugate fault analysis was reliable. Using a sandbox model, a break was formed that was comparable to the position and orientation of the boundary between regions two and three on the macroscale maps.This supported the notion that the break in the overlying thrust sheet may have formed via a complex interaction of an eastward-moving thrust sheet over an oblique ramp. Analysis of epoxied sandbox samples was also supportive. Samples taken from the frontal ramp region accommodated transport to the east, while samples from the oblique ramp region accommodated transport to the southeast.After watching this video, you should have a good understanding of how to build, run, and modify sandbox models to replicate a specific field area. Once mastered, this technique can be done in one week if performed properly. After its development, this technique paved the way for researchers in the field of structural geology to explore the usefulness of fault data and how these data can be further interpreted with the aid of models.Thanks for watching and good luck with your models.

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8.1K vistas.  Franklin and Marshall College. The overall goal of this experiment is to track the deformation of thrust sheets as they move over oblique ramps. This method can help answer key questions in the field, such as how thrust sheets evolve in complex settings. The main advantages of this technique are that it is simple, inexpensive, and can be compared directly to the field data.This video shows how to use a push-block sandbox to replicate micro-scale faults found in the field. Field identification of micro-scale faults i...