POOL MERINGUE: A NEW SPELEOTHEM FOUND IN CARLSBAD CAVERN, NEW MEXICO

Carlsbad Cavern, Carlsbad Caverns National Park, New Mexico contains many current and fossil cave pools. We examined seventeen pool areas (21 individual pools, mostly fossil) in the Lower Cave section of Carlsbad Cavern and found a previously unknown speleothem we call pool meringue. Pool meringue is a thin 2-4 mm overgrowth of crystalline calcite that sometimes coats the bottoms or sides of cave pools. Out of the 21 pools described, pool meringue occurs in four. It is different from the usual pool crust because it has a smooth surface, typically develops small peaks (like meringue pie), and forms on top of pool crust or pool fingers. Pool meringue appears as overgrowths on pool fingers, fills preexisting cracks, or coats ridged or knobby pool crust. The top of the meringue ridges is either sharp points or smooth curves. Pool meringue typically coats a significant portion of the pool bottom although it may be restricted to a lower water level.

Three of the four occurrences of pool meringue also had webulite, a pool speleothem consisting of paper-thin, connected webs of calcite usually connecting two or more pool fingers or other hanging speleothems. An additional pool contained webulite alone. Pool meringue’s crystalline structure appears identical to the coexisting webulite and both exhibit a milky, transparent color and form as overgrowths. Webulite has not been well studied either but its webby form strongly suggests formation by calcification of microbial slime. The close connection between webulite and pool meringue also suggests a microbial origin but further data are required to test this hypothesis.