RAPID ENTRENCHMENT OF STREAM PROFILES IN THE SALT CAVES OF MOUNT SEDOM, ISRAEL, 1995, Frumkin A, Ford Dc,

Rock salt is approximately 1000 times more soluble than limestone and thus displays high rates of geomorphic evolution. Cave stream channel profiles and downcutting rates were studied in the Mount Sedom salt diapir, Dead Sea rift valley, Israel. Although the area is very arid (mean annual rainfall approximate to 50 mm), the diapir contains extensive karst systems of Holocene age. In the standard cave profile a vertical shaft at the upstream end diverts water from a surface channel in anhydrite or elastic cap rocks into the subsurface route in the salt. Mass balance calculations in a sample cave passage yielded downcutting rates of 0.2 mm s(-1) during peak flood conditions, or about eight orders of magnitude higher than reported rates in any limestone cave streams. However, in the arid climate of Mount Sedom floods have a low recurrence interval with the consequence that long-term mean downcutting rates are lower: an average rate of 8.8 mm a(-1) was measured for the period 1986-1991 in the same sample passage. Quite independently, long-term mean rates of 6.2 mm a(-1) are deduced from C-14 ages of driftwood found in upper levels of 12 cave passages. These are at least three orders of magnitude higher than rates established for limestone caves. Salt cave passages develop in two main stages: (1) an early stage characterized by high downcutting rates into the rock salt bed, and steep passage gradients; (2) a mature stage characterized by lower downcutting rates, with establishment of a subhorizontal stream bed armoured with alluvial detritus. In this mature stage downcutting rates are controlled by the uplift rate of the Mount Sedom diapir and changes of the level of the Dead Sea. Passages may also aggrade. These fast-developing salt stream channels may serve as full-scale models for slower developing systems such as limestone canyons

Uplift rate relative to base-levels of a salt diapir (Dead Sea Basin, Israel) as indicated by cave levels, 1996, Frumkin A,

Rapid downcutting rates in the extremely soluble salt of the Sedom diapir, Dead Sea basin, Israel, allow cave channels to become rapidly graded with respect to base level. Diapir uplift leaves the older passages high and dry above present base level. Dating these passages by 14C allows us to estimate diapir uplift rates, taking into account previous Dead Sea levels. Maximum mean Holocene uplift rates are 6-7 mm a-1 along the eastern fault of Mount Sedom

A minimum age for canyon incision and for the extinct Molossid bat, Tadarida constantinei, from Carlsbad Cavers National Park, New Mexico, 2006, Lundberg J. , Mcfarlane D. A.

Slaughter Canyon Cave (or New Cave), Carlsbad Caverns National Park, southeastern New Mexico, opens in the wall of Slaughter Canyon, 174 m above the present level of the canyon floor. It contains bone-bearing, water-laid sediments capped by a double layer of calcite. TIMS U-Th dates on the two layers are 66.0 ± 0.3 ka and 209 ± 9 ka. Deposition of these two laterallyextensive calcite layers suggests wet periods in this currently-arid region during MIS 4 and 7. The date on the lower layer suggests that the clastic deposit was emplaced no later than MIS 8. This yields a maximum estimate for downcutting rate of the canyon of ~0.87 mm yr-1during the Late Pleistocene. The clastic deposit contains bones of the molossid bat Tadarida constantinei Lawrence 1960: the date of 209 ± 9 ka is thus a minimum age for this extinct bat.