Corroded cobbles in Southern Death Valley: Their relationship to honeycomb weathering and lake shorelines

Abstract

In southern Death Valley, pits similar in morphology to honeycomb weathering (herein referred to as corrosion pits) occur on the surfaces ofcobbles that are associated with wave-produced benches. The pitted cobbles include a variety of igneous, metamorphic, and siliciclastic rocks; corrosion pits are rare to absent in limestones or dolomites. Pit morphology is controlled by cobble lithology. In massive rocks the pits are arcuate, elongate, and gently tapering; corrosion of laminated or foliated rocks has produced irregular, more jagged pits. The presence of desert varnish has strongly inhibited the corrosion process.The corroded cobbles are inferred to reflect both chemical and physical weathering of rocks along Pleistocene lacustrine strandlines. Corrosion took place through salt-weathering and/or heat-moisture expansion processes and through chemical dissolution of selected minerals as a result of splash-zone wetting and drying. The ancient lake waters may have had high pH and high total dissolved solids contents. The recognition of corroded cobbles may be important in the reconstruction of the position of ancient shorelines for certain types of alkaline lakes and in the reconstruction of their ancient chemistries.

Sandstone weathering: a century of research and innovation

“…For examples, disaggregation of grains and pore-infilling by salts may coincide with etching of quartz grains and feldspars (e.g., McGreevy and Smith, 1984;Butler and Mount, 1986). Salt weathering is not invariably the cause of tafoni formation, but salts are often present in tafoni backwalls and flakes and cause disintegration both through physical and chemical processes.…”

Complex weathering in drylands: Implications of ‘stress’ history for rock debris breakdown and sediment release

“…This recognition that many 'characteristic' desert landforms are inherited features has not been so widely acknowledged in the study of smaller-scale weathering forms developed on outcrops and released debris. Yet scale differences should not preclude consideration that many smaller scale debris weathering forms may not be the direct product of the environmental conditions in which they are currently found (Butler and Mount, 1986) and, that past conditions may have a profound effect on the weathering response of debris to contemporary conditions.…”

Rates and patterns of bedrock denudation by coastal salt spray weathering: A seven‐year record

“…This paper investigates rates of coastal denudation of greenschist in the supratidal zone on the Start-Prawle peninsula in south Devon, United Kingdom (Figure 1). The nature of the rock weathering processes operating in the study location is indicated by the abundance of honeycomb weathering patterns on exposed surfaces; these features are commonly regarded as indicative of weathering by salt crystallization (Bartrum, 1936;Mustoe, 1982Mustoe, , 1983McGreevey, 1985a;Butler and Mount, 1986). Studies by the present author (Mottershead, 1981(Mottershead, ,1982(Mottershead, ,1983 have demonstrated that rock denudation is indeed active, with a mean rate of surface lowering derived from 34 points over a one year period measured by micro-erosion meter (MEM) of 0.61 mm a-'.…”