Sandstone Phenomenon of the East Greenland

Richard G. Bromley and Radek Mikuláš

Geological Institute, University of Copenhagen, Oster Voldgade 10, DK-1350 Copenhagen K, Denmark

and

Institute of Geology, Academy of Sciences of the Czech Republic, Rozvojová 135, 165 02 Praha 6, Czech Republic

Weathering of the Jurassic thick-bedded quartzose sandstones in East Greenland (Jameson Land) is controlled chiefly by freezing water. Less cemented parts are weathered away leaving high cliffs and pinnacles of the harder material. Lichens grow on these hard surfaces. Very large lichen specimens and very slow growing (centuries old) show that the hard cemented sandstones weather very slowly. Some pinnacles have castellated tops. Verticals walls are ornamented almost exclusively by horizontal (or oblique, if cross-bedded or fallen) ledges. Honeycomb surfaces of tafoni-like forms are rare; they are irregular, showing pits and hollows of a broad range of sizes and shapes. Manifestations of case hardening (rock crusts) are almost absent, apparently because of insufficient evaporation of water solutions form the sandstone surfaces.