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.