Weathering Processes and Forms

Smith, Bernard

doi:10.1007/978-1-4020-5719-9_4

Cited by 25 publications

(5 citation statements)

References 195 publications

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“…Drill hole show salt crystallisation at the immediate rock surface. This pattern occurs after evaporation of surface-wetted rock, provided that "the rate of evaporation is lower than the potential rate of outward salt solution migration" ( [47], p. 80 f.). This is probably the case in the caves where seasonal surface-wetting occurs by condensation and the evaporation rate in the shielded caves is low.…”

Section: Distribution and Phase Changes Of Saltsmentioning

confidence: 99%

The role of moisture and salt distribution in the weathering of the medieval cave town of Uplistsikhe, Georgia

Sass,

Heil

2024

Preprint

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Knowledge of salt and moisture distribution is a key factor for understanding rock decay at cultural heritage sites. The cave town of Uplistsikhe in Georgia, carved from sandstone in late bronze age to medieval times, suffers from progressive scaling and flaking processes. Multi-method investigations of rock moisture and salt distribution were carried out in order to better understand the patterns of decay. Salt distribution was investigated using drill dust samples and paper pulp poultices; moisture was determined by 2D-resistivity and handheld microwave sensors, supplemented by infrared thermography. The combined results from the different methods revealed a complex pattern of salt and moisture distribution. An most sites, K2SO4 (arcanite) and its hydrates dominate, sometimes in combination with CaSO4 (gypsum). At one site (Grandhall), halite (NaCl) and niter (KNO3) prevail. Sulphates are assumed to be a legacy of air pollution; origin of halite and niter remains unsolved but might be due to concrete reinforcements. Two main sources of moisture were evidenced depending on season and spatial situation: (1) Condensation of air humidity at cool cave backwalls in spring (combined with and aided by salt efflorescence), evidenced by 2D-resistivity and infrared thermography; (2) seepage along joints particularly at the cave backwalls and roofs, evidenced by handheld microwave sensors. Further investigations should focus on identifying seepage pathways and on clarifying the origin of destructive halite and nitrates.

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Section: Distribution and Phase Changes Of Saltsmentioning

confidence: 99%

The role of moisture and salt distribution in the weathering of the medieval cave town of Uplistsikhe, Georgia

Sass,

Heil

2024

Preprint

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“…Second, dirt cracking is not the only process that spalls surfaces. An abundance of other rock morbidity processes operate on desert landforms (Brandmeier et al, 2011;Dorn et al, 2013;Gadd, 2017;Smith, 2009;Sumner et al, 2009;Viles, 2013;Warke, 2007), but life expectancies in Table 2 reflect only the process of dirt cracking.…”

Section: Rate Of Varnishing Vs Time To Cover Up Dirt Crackingmentioning

confidence: 99%

“…Studies of geomorphic processes influencing desert bedrock landforms reveal that spalling events <10 cm are quite common (Blackwelder, 1925;Dorn, 1995b;Dragovich, 1993;Hobbs, 1918;Mabbutt, 1977;Moses et al, 2014;Ollier, 1965;Paradise, 2005;Smith, 2009;Sumner et al, 2009;Viles, 2013;Viles and Goudie, 2007;Warke, 2007). Thus, geomorphologists must use methods other than cosmogenic nuclides to understand rates of such processes as dirt cracking (Ollier, 1965), exfoliation (Blackwelder, 1925), fire-induced spalling (Dragovich, 1993), clast-size reduction in desert pavements (Mabbutt, 1977), flaking from salt weathering (Smith, 2009), and other sorts of rock breakdown (Warke, 2007). This paper specifically explores how to measure rates of dirt cracking (Ollier, 1965) on desert bedrock landforms.…”

Section: Introductionmentioning

confidence: 99%

Necrogeomorphology and the life expectancy of desert bedrock landforms

Dorn

2018

Progress in Physical Geography: Earth and Environment

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This paper presents the first estimates for the life expectancy of the very surface of bedrock desert landforms, such as bornhardts, cliff faces, fault scarp, inselbergs, ridge crests, and slickrock. The correlative dating method of varnish microlaminations yields minimum ages for the timing of the last spalling event caused by the physical weathering process of dirt cracking. Minimum percentage of a bedrock surface spalled per thousand years is a metric that can be estimated using multiple varnish lamination ages. Understanding rates of surface spalling provides a quantitative measure of Gilbert’s (1877: 105) weathering-limited ‘rate of disintegration’, because this metric directly links to the rock disintegration process of dirt cracking. Rates of percent surface spalled then translate into estimates of how long it takes for the very surface of a desert bedrock landform to die. For a variety of example landforms in the southwestern USA, the maximum time required to completely resurface a desert bedrock landform by spalling from dirt cracking ranges from 89 to 600 ka.

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“…It is possible for caverns to form in bedrock by the progressive wearing back of specific areas of cliff face to form features that are often referred to as 'tafoni'. These are particularly common within Mediterranean and arid environments, but are typical of salt-rich environments in general and are considered by many to be diagnostic of salt weathering (Smith 2009). There appear to be maximum dimensions to tafoni as their growth is self-limiting through the eventual loss of significant thermal cycling, and their dimensions are invariably measured in metres or fractions of metres, rather than the tens of metres that characterise the Haua Fteah (Smith 1978).…”

Section: Ground-based Lidar Survey Of the Haua Fteah Morphometrymentioning

confidence: 99%

The Cyrenaican Prehistory Project 2010: the fourth season of investigations of the Haua Fteah cave and its landscape, and further results from the 2007–2009 fieldwork

et al. 2010

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The paper reports on the fourth (2010) season of fieldwork of the Cyrenaican Prehistory Project, and on further results of analyses of artefacts and organic materials collected in the 2009 season. Ground-based LiDar has provided both an accurate 3D scan of the Haua Fteah cave and information on the cave's morphometry or origins. The excavations in the cave focussed on Middle Palaeolithic or Middle Stone Age ‘Pre-Aurignacian’ layers below the base of the Middle Trench beside the McBurney Deep Sounding (Trench D) and on Final Palaeolithic ‘Oranian’ layers beside the upper part of the Middle Trench (Trench M). Although McBurney referred to the upper part of the Deep Sounding as more or less sterile, the 2010 excavations found evidence for small-scale but regular human presence in the form of stone artefacts and debitage, though given the sedimentary context the latter are unlikely to represent in situ knapping. The excavations of Trench M extended from the basal Capsian layers investigated in 2009 through Oranian layers to the transition with the Dabban Upper Palaeolithic. Some 17,000 lithic pieces have been studied from the Capsian and Oranian layers excavated in Trench M, in an area measuring less than 2 m by 1 m by 1.1 m deep, along with numerous animal bones, molluscs, and macrobotanical remains, as well as occasional shell beads. Preliminary studies of the lithics, bones, molluscs, and plant remains are revealing the changing character of late Pleistocene (Oranian) and early Holocene (Capsian) occupation in the Haua Fteah. Alongside the work in the Haua Fteah, the project continued its assessment of the Quaternary and archaeological sequences of the Cyrenaican coastland and completed a transect survey of surface lithic materials and their landform contexts from the pre-desert across the Gebel Akhdar to the coast, with a new focus on the al-Marj basin. Significant differences are emerging in patterns of Middle Palaeolithic and later hominin occupation and palaeodemography.

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Weathering Processes and Forms

Cited by 25 publications

References 195 publications

The role of moisture and salt distribution in the weathering of the medieval cave town of Uplistsikhe, Georgia

The role of moisture and salt distribution in the weathering of the medieval cave town of Uplistsikhe, Georgia

Necrogeomorphology and the life expectancy of desert bedrock landforms

The Cyrenaican Prehistory Project 2010: the fourth season of investigations of the Haua Fteah cave and its landscape, and further results from the 2007–2009 fieldwork

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