Origins of honeycomb weathering: The role of salts and wind

Citation
C. Rodriguez-navarro et al., Origins of honeycomb weathering: The role of salts and wind, GEOL S AM B, 111(8), 1999, pp. 1250-1255
Citations number
52
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Earth Sciences
Journal title
GEOLOGICAL SOCIETY OF AMERICA BULLETIN
ISSN journal
0016-7606 → ACNP
Volume
111
Issue
8
Year of publication
1999
Pages
1250 - 1255
Database
ISI
SICI code
0016-7606(199908)111:8<1250:OOHWTR>2.0.ZU;2-W
Abstract
Honeycomb weathering is a common surface phenomenon affecting a variety of rocks in a range of environments. It develops on building stones and it sha pes ocean cliffs, rocks in hot deserts, and Arctic landscapes. Honeycomb we athering may also help alter rocks on other planets, such as Mars. Although first noted in the nineteenth century, its origins are still not wed under stood, and a dearth of laboratory experiments testing the many theories pro posed for its development has added to the ambiguity. Incipient honeycomb w eathering in a homogeneous limestone has been experimentally reproduced by wind exposure and salt crystallization. Our experiments show that heterogen eous wind flow over a stone surface is important in the development of this weathering pattern. Wind promotes evaporative salt growth between grains o n a stone surface, resulting in the development of small, randomly distribu ted cavities, A reduction in air pressure within the cavities results in in creased wind speed and rapid evaporation. A high evaporation rate and evapo rative cooling of the saline solution in the cavity leads to more rapid and greater granular disintegration than in the surrounding areas. It seems th at this local supersaturation and subsequent buildup of salt crystallizatio n pressure ultimately result in the formation of honeycomb features. For th e first time, these experimental results demonstrate the close relationship between salts, wind, and honeycomb weathering. They also offer new ways to understand the genesis of this striking and sometimes harmful weathering p attern.