An index for describing the core-stone shape in weathered columnar joints

Yang, Zon-Yee; Wu, Tsung-Hsing

doi:10.1007/s10706-005-2213-8

Cited by 6 publications

(2 citation statements)

References 6 publications

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“… Yingst et al [2007] quantify elongation, sphericity and curvature of boulders at the Mars Pathfinder landing site using boulder axis measurements and inscription of circles to boulder perimeters and edges. Rouai and Dekayir [2001] and Yang and Wu [2006] employ the fractal box‐counting method on the perimeter of a 2 d projection of the boulder. Durian et al [2006] image clasts and trace their outlines and find that boulders from different environments have varying statistical distribution of curvatures.…”

Section: Introductionmentioning

confidence: 99%

Quantitative morphologic analysis of boulder shape and surface texture to infer environmental history: A case study of rock breakdown at the Ephrata Fan, Channeled Scabland, Washington

2008

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[1] Boulder morphology reflects both lithology and climate and is dictated by the combined effects of erosion, transport, and weathering. At present, morphologic information at the boulder scale is underutilized as a recorder of environmental processes, partly because of the lack of a systematic quantitative parameter set for reporting and comparing data sets. We develop such a parameter set, incorporating a range of measures of boulder form and surface texture. We use standard shape metrics measured in the field and fractal and morphometric classification methods borrowed from landscape analysis and applied to laser-scanned molds. The parameter set was pilot tested on three populations of basalt boulders with distinct breakdown histories in the Channeled Scabland, Washington: (1) basalt outcrop talus; (2) flood-transported boulders recently excavated from a quarry; and (3) flood-transported boulders, extensively weathered in situ on the Ephrata Fan surface. Size and shape data were found to distinguish between flood-transported and untransported boulders. Size and edge angles ($120°) of floodtransported boulders suggest removal by preferential fracturing along preexisting columnar joints, and curvature data indicate rounding relative to outcrop boulders. Surface textural data show that boulders which have been exposed at the surface are significantly rougher than those buried by fan sediments. Past signatures diagnostic of flood transport still persist on surface boulders, despite ongoing overprinting by processes in the present breakdown environment through roughening and fracturing in situ. Further use of this quantitative boulder parameter set at other terrestrial and planetary sites will aid in cataloging and understanding morphologic signatures of environmental processes.Citation: Ehlmann, B. L., H. A. Viles, and M. C. Bourke (2008), Quantitative morphologic analysis of boulder shape and surface texture to infer environmental history: A case study of rock breakdown at the Ephrata Fan, Channeled Scabland, Washington,

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Section: Introductionmentioning

confidence: 99%

Quantitative morphologic analysis of boulder shape and surface texture to infer environmental history: A case study of rock breakdown at the Ephrata Fan, Channeled Scabland, Washington

2008

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“…Slower cooling and rhyolitic compositions promote larger columnar joint spacing with bounding polygonal joint segment lengths as large as 3-4 m (Hetényi et al, 2012). Secondary, horizontal fracturing segments the columns into blocks (e.g., Yang & Wu, 2006), which are then weathered physically and chemically to produce smaller fragments and round the blocks (e.g., Moon & Jayawardane, 2004). In the case of Bishop Tuff, this set of blocks is exposed now (typical diameters as much as 1-2 m) on the tops of the scarps, and from there blocks are further fractured and transported (see figure 3 in Ferrill et al, 2016; Figures 1 and 2).…”

Section: Rocky Fault Scarpsmentioning

confidence: 99%

Quantifying and analysing rock trait distributions of rocky fault scarps using deep learning

Chen

Scott

Keating

et al. 2023

Earth Surf Processes Landf

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We apply a deep learning model to segment and identify rock characteristics based on a Structure‐from‐Motion orthomap and digital elevation model of a rocky fault scarp in the Volcanic Tablelands, Eastern California, USA. By post‐processing the deep learning results, we build a semantic rock map and analyse the rock trait distributions. The resulting semantic map contains nearly 230 000 rocks with effective diameters ranging from 2 to 250 cm. Rock trait distributions provide a new perspective on rocky fault scarp development and extend past research on scarp geometry including slope, height and length. Heatmaps indicate rock size spatial distributions on the fault scarp and surrounding topographic flats. Median grain size changes perpendicular to the fault scarp trace, with the largest rocks on the downslope proximal to the scarp footwall. Correlation analyses illustrate the relationship between rock trait statistics and fault scarp geomorphology. Local fault scarp height correlates with median grain size ( R2 = 0.6), the mean grain size of the largest rocks ( R2 = 0.8) and the ratio of the number of small to large rocks ( R2 = 0.4). The positive correlation ( R2 = 0.8) between local fault scarp height and standard deviation of grain size suggests that rocks on a higher fault scarp are less well sorted. The correlation analysis between fault scarp height and rock orientation statistics supports a particle transportation model in which locally higher fault scarps have relatively more rocks with long axes parallel to fault scarp trace because rocks have a larger distance to roll and orient the long axes. Our work demonstrates a data‐driven approach to geomorphology based on rock trait distributions, promising a greater understanding of fault scarp formation and tectonic activity, as well as many other applications for which granulometry is an indicator of process.

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Classification on Shape of Granitoid Boulder Based on Size and Surface Roughness from Various Weathering Zones for Site Investigation Purposes

Azlan

Marcos

Mohammad

et al. 2020

IOP Conf. Ser.: Earth Environ. Sci.

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Boulder is often posed challenges to earthwork activities such as cut slope and foundation excavation especially in tropical weathered rock like Malaysia. In addition, the guidelines for hard material or rock excavation related to boulder provided by Department of Works Malaysia (JKR) are limited and there is a need to be revised. Therefore, this study aims to establish a classification chart of boulder’s shape in different weathering zones for site investigation purposes. The parameters of size, volume and characteristics of surface roughness from moderately to completely weathered zone were measured and analysed statistically. Results of this study show that the increase of weathering zone from zone 3 to 5 significantly reducing the size and volume of boulder with reduction of 27% and 38.3%, respectively. Boulder in Zone 3 to Zone 5 can be classified into six typical sphericities: very flat, flat, sub- flat, sub-spherical, spherical and well-spherical. The results also revealed that the physical parameters of boulder can be classified into six classes based on Roundness Ratio (Rr) and Surface Roughness Index (SRI). Based on these results, a boulder shape classification chart was developed and useful as a guideline for engineering application especially in soil investigation purposes.

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An index for describing the core-stone shape in weathered columnar joints

Cited by 6 publications

References 6 publications

Quantitative morphologic analysis of boulder shape and surface texture to infer environmental history: A case study of rock breakdown at the Ephrata Fan, Channeled Scabland, Washington

Quantitative morphologic analysis of boulder shape and surface texture to infer environmental history: A case study of rock breakdown at the Ephrata Fan, Channeled Scabland, Washington

Quantifying and analysing rock trait distributions of rocky fault scarps using deep learning

Classification on Shape of Granitoid Boulder Based on Size and Surface Roughness from Various Weathering Zones for Site Investigation Purposes

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