Rates of development of tafoni in the Moenkopi and Kaibab formations in Meteor Crater and on the Colorado Plateau, northeastern Arizona

Norwick, Stephen A.; Dexter, Leland R.

doi:10.1002/esp.276.abs

Cited by 7 publications

(14 citation statements)

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“…Siedel (2010), used ''alveoli,'' ''pits,'' and ''honeycombs'' interchangeably even after recognizing the existence of ''some terminological confusion in the use of 'alveolar' or 'honeycomb weathering''' (Siedel, 2010: 12). Other abstracts and introductions from numerous publications include statements such as ''a multitude of terms have been used to describe such features'' (McBride and Picard, 2000: 869) or ''the nomenclature for pitted and cavernous weathering was not harmonized throughout most of the twentieth century'' (Norwick and Dexter, 2002), but no such study explicitly calls for a unified lexicon. The latter example cited Sunamura (1996) as the official foundation of using ''tafoni'' as a non-scalar term, but the exact passage cited was simply a disclaimer for that particular study: ''These two cavernous forms are, however, collectively called 'tafoni' in this paper, unless otherwise stated'' (Sunamura, 1996: 741).…”

Section: Modern Scientific Discoveries and Tafoni Terminologymentioning

confidence: 99%

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Defining tafoni

Groom

Allen

Mol

et al. 2015

Progress in Physical Geography: Earth and Environment

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Cavernous rock decay processes represent a global phenomenon, ubiquitous to all environments, with the viewable-in-landscape form usually being the final descriptor (e.g. ''alveoli''), sometimes alluding to the specific decay process (e.g. ''pitting''), other times not (e.g. ''honeycombing''). Yet, definitive terminology remains inconsistent, usually owing to variability in dimension, morphometry, distribution, and/or academic lineage. This lack of an established lexicon limits scientific collaboration and can generate scientific bias. With no official consensus on appropriate distinctions, researchers and scientists must either be familiar with all the possible terminology, or know the apparent distinction between ''forms''-which can seem arbitrary and, even more frustrating, often differs from researcher to researcher, scientist to scientist. This article reviews the historical and contemporary progression of scientific inquiry into this decay-and, arguably, erosionalfeature to identify lexical inconsistencies and promote a singular unifying term for future scholars. Ultimately, the authors support using ''tafoni'' (singular: ''tafone'') as the non-scalar universal term-the form created by numerous processes involved in cavernous decay features-and strongly suggest researchers adopt the same vernacular in order to promote collaboration.

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Section: Modern Scientific Discoveries and Tafoni Terminologymentioning

confidence: 99%

“…Bryan, 1928;Tschang, 1974) and temporal modeling of cell growth (e.g. Norwick and Dexter, 2002;Sunamura, 1996), to meticulous laboratory analyses (e.g. McBride and Picard, 2004;Rodriguez-Navarro et al, 1999) and complex multidisciplinary field studies (e.g.…”

Section: Introductionmentioning

confidence: 99%

Defining tafoni

Groom

Allen

Mol

et al. 2015

Progress in Physical Geography: Earth and Environment

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“…-The continuing accumulation of CRNs beneath thin (< 3 m) rock cover and snow cover during periods when pit deepening is not possible. -The disparity between approximately constant CRN production and non-linear rates of pit deepening (Norwick and Dexter 2002). -The range of pit depths found on some surfaces indicates that pit formation may occur long after the surface is first exposed -Variations across a surface.…”

Section: Cosmogenic Exposure Agesmentioning

confidence: 99%

“…11). We use a sigmoidal curve to estimate variations in weathering pit depth against time for two reasons: (i) previous studies of tafoni development through time indicate that rates of deepening follow sigmoidal functions (Norwick and Dexter 2002;Sunamura 1996); and (ii) average rates of pit deepening in the Cairngorms are 4.5 mm/ka of exposure, signifi- A and B). Deeper pits may be inherited from earlier ice-free intervals.…”

Section: Cosmogenic Exposure Agesmentioning

confidence: 99%

“…New pits develop (G) and regolith starts to reform around the slab (H) cantly above postglacial rates of 1-3.3 mm/ka and adding support to the idea that pit initiation is slow. Following Norwick and Dexter (2002), we computed best-fit solutions using Excel Solver to several types of equations using our weathering pit depth and surface exposure age data. A sigmoidal equation of the form D = b1+exp(b2+b3/t), with b1 forced to be equal to zero, yielded the most realistic fit (Fig.…”

Section: Cosmogenic Exposure Agesmentioning

confidence: 99%

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Weathering pits as indicators of the relative age of granite surfaces in the cairngorm mountains, scotland

Hall

Phillips

2006

Geografiska Annaler: Series A, Physical Geography

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Weathering pits as indicators of the relative age of granite surfaces in the Cairngorm Mountains, Scotland. Geogr. Ann., 88 A (2): 135-150.ABSTRACT. Weathering pits 1-140 cm deep occur on granite surfaces in the Cairngorms associated with a range of landforms, including tors, glacially exposed slabs, large erratics and blockfields. Pit depth is positively correlated with cosmogenic exposure age, and both measures show consistent relationships on individual rock landforms. Rates of pit deepening are non-linear and a best fit is provided by the sigmoidal function D = b1 + exp(b2+b3/t). The deepest pits occur on unmodified tor summits, where 10 Be exposure ages indicate that surfaces have been exposed to weathering for a minimum of 52-297 ka. Glacially exposed surfaces with pits 10-46 cm deep have given 10 Be exposure durations of 21-79 ka, indicating exposure by glacial erosion before the last glacial cycle. The combination of cosmogenic exposure ages with weathering pit depths greatly extends the area over which inferences can be made regarding the ages of granite surfaces in the Cairngorms. Well-developed weathering pits on glacially exposed surfaces in other granite areas are potential indicators of glacial erosion before the Last Glacial Maximum.

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New challenges for tafoni research. A new approach to understand processes and weathering rates

Brandmeier

Kuhlemann

Krumrei

et al. 2010

Earth Surf Processes Landf

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Cavernous tafoni-type weathering is a common and conspicuous global feature, creating artistic sculptures, which may be relevant for geochemical budgets. Weathering processes and rates are still a matter of discussion. Field evidence in the type locality Corsica revealed no trend of size variability from the coast to subalpine elevations and the aspect of tafoni seems to be governed primarily by the directions of local fault systems and cleavage, and only subordinately by wind directions or the aspect of insulation. REM analysis of fresh tafone chips confirmed mechanical weathering by the crystallization of salts, as conchoidal fracturing of quartz is observed. The salts are only subordinately provided by sea spray, as calcium and sodium sulfates rather than halite dominate even close to the coast. Characteristic element ratios compare well with aerosols from mixed African and European air masses. Sulfates are largely derived from Sahara dust, indicated by their sulfur isotopic composition. Salt crystals form by capillary rise within the rock and subsequent crystallization in micro-cracks and at grain boundaries inside rain-protected overhangs. Siderophile bacteria identified by raster electron microscopy (REM) analysis of tafone debris contribute to accelerated weathering of biotite and tiny sulfide ore minerals. By applying 10 Be-exposure dating, weathering rates of large mature tafone structures were found to be about an order of magnitude higher than those on the exposed top of the affected granite blocks.

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Rates of development of tafoni in the Moenkopi and Kaibab formations in Meteor Crater and on the Colorado Plateau, northeastern Arizona

Cited by 7 publications

References 0 publications

Defining tafoni

Defining tafoni

Weathering pits as indicators of the relative age of granite surfaces in the cairngorm mountains, scotland

New challenges for tafoni research. A new approach to understand processes and weathering rates

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