More on Snottites…

Title: More on Snottites…

Author: Harvey DuChene

Publication: The Outcrop, March 2001, p. 8-9

When I read the article about ‘snottites’ in the November RMAG Outcrop, I felt compelled to provide more information. I have first-hand experience with these unusual features, having visited the only two caves in the world where they have been identified. As the article in Geotimes indicated, Dr. Jim Pisarowicz named the features in Mexico in the mid-1980’s when he first visited Cueva de Villa Luz, Tabasco. Along with Jim and a team of geologists and biologists led by Dr. Louise Hose, I visited Villa Luz in January of 1998 to study the snottites and other extraordinary features in this rather hostile environment.

The snottites consist of a mucous-like substance that accumulates on spider webs that are attached to a substrate of gypsum crystals. Due to the high humidity of the cave, all of the rock surfaces are quite moist, and this water is relatively rich in dissolved oxygen. There are numerous springs that emit H2S into the atmosphere throughout the cave. The groundwater feeding these springs is depleted in oxygen, so the H2S has not been converted to sulfuric acid. However, the H2S that evolves into the cave atmosphere is quickly re-dissolved into water on bedrock surfaces and is oxidized, becoming sulfuric acid. Where the acid is in direct contact with limestone, it reacts to form gypsum. Much of this gypsum is a dirty-white paste, but some of it has crystallized on downward-facing surfaces, forming a carapace that shields the limestone. Where H2S is dissolved into oxygenated water on the surface of the gypsum, it persists as sulfuric acid that becomes more concentrated with time.

The water in the snottites has a pH of 0.2. The highly acidic water on the spider webs would seem to be a rather hostile environment for life, yet microbes abound. These life forms are being studied by biologists, geologists and geochemists that are trying learn more about this remarkable habitat. Hose and Pisarowicz (1999) and Hose et al., (2000) published the first results of investigations in Cueva de Villa Luz.

In an interesting example of parallel research, a team of Italian and Romanian geologists and biologists are studying Grotta Grande del Vento in the Frasassi Gorge of the Apennine Mountains of central Italy. This cave, and several others in the area, was dissolved by sulfuric acid, a process that is currently active in caves near stream (base) level. The team identified features identical to those in Villa Luz, including “mucolites” (Sarbu et al., 1998: Galdenzi et al., 1999). The Italian mucolites appear to be identical to the snottites of Cueva de Villa Luz. I suppose that there will be some discussion as to which term will prevail in the literature, since the discoveries in Italy and Mexico occurred at about the same time in the mid-1980’s, and publication of the terms was almost simultaneous.

Whatever they are called, snottites and/or mucolites, as well as other geomicrobiological features in these caves, are unusual environments for living things. That is why scientists who are interested in the search for extraterrestrial life are studying them, and the caves where they are found. The search for life in extreme environments is a focus of NASA research that includes sulfur-based ecosystems in deep oceanic smokers, in the hot springs of Yellowstone National Park, and sulfuric acid caves worldwide. For those who are interested, there are a number of recent publications discussing this fascinating subject, as well as television programs produced by NOVA and The Discovery Channel.

There are no known “living” snottites in Lechuguilla Cave (Carlsbad Caverns National Park), but there are features called “u-loops” that could be fossilized snottites. The sulfuric acid events that formed Lechuguilla Cave ceased more than 4 ma (Polyak et al., 1998), bringing an end to the environmental conditions that may have allowed snottites to develop. We do not know for certain if u-loops are fossilized snottites, but the similarity between them is striking.

Selected References

Davis, D.G., 2000, Extraordinary features of Lechuguilla Cave, Guadalupe Mountains, New Mexico: Journal of Cave and Karst Studies, v. 62, in press.

Davis, D.C., Palmer A.N., and Palmer, M.A., 1990, Extraordinary subaqueous speleothems in Lechuguilla Cave, New Mexico: National Speleolcuical Society Bulletin, v. 52, p. 70-86.

DuChene, H.R., (1997), Lechuguilla Cave. New Mexico, U.S.A. In Hill, C. A., and Forti. P., Cave Minerals of the World, Second Edition: National Speleological Society: p. 343-350.

DuChene, H.R., 2000, Bedrock features of Lechugui]la Cave, Guadalupe Mountains, New Mexico: Journal of Cave and Karst Studies, v. 62. in press.

Hill, C.A., 2000, Overview of the Geologic History of Cave Development in the Guadalupe Mountains, New Mexico: Journal of Cave and Karst Studies, v. 62, in press.

Hose, L.D., Palmer, A.N., Palmer, M.V., Northup, D.E., Boston, P.J., and DuChene, H.R., 2000, Microbiology and Geochemistry in a hydrogen-sulphide-rich karst environment: Chemical Geology, v. 169, p. 399-423.

Hose, L.D. , and Pisarowicz, J.A., 1999, Cueva de Villa Luz, Tabasco. Mexico: Reconnaissance study of an active sulfur spring cave and ecosystem:

Norlhup, D.E., Dahm, C.N, Melim, L.A., Spilde, M.N., Crossey, L.J., LaVoie, K.H., Mallory, L. M., Boston, P.J., Cunningham, K.I., and Barns, S.M., 2000, Evidence for Geomicrobiological Interactions in Guadalupe Caves: Journal of Cave and Karst Studies, v. 62, in press.

Polyak, V.J., McIntosh, W.C., Güven, N. & Provencio, P. (1998), Age and origin of Carlsbad Cavern and related caves from 40Ar/39Ar of alunite: Science v. 279, p. 1919-1922.