GEOBIOCHEMICAL AND GEOPHYSICAL CHARACTERISTICS OF WHITE SULFUR SPRING, THERMOPOLIS, WY

White Sulfur Spring (WSS) is located approximately 500m north of the Big Spring (main outflow) in Hot Springs State Park, along the eastern bank of the Big Horn River in Thermopolis, Wyoming. Unlike the Big Spring, which exists as a 20-m diameter high-flow pool, WSS trickles out of the side of the cliff, below travertine terraces, only a meter above the river level, at a slightly higher temperature of ~54^oC. Rather than forming a pool, the outflow from WSS is a constantly flowing 10-cm wide, 1- to 3-cm deep channel, flowing out of a small cave and directly into the river. The channel is lined with a smooth, white mineral coating with bright green bacterial growth restricted to the edges of the channel, rimmed with gold/yellow bacterial away from the flow.

The clear flow emanates from the back of this cave onto a floor coated with gray sand and minerals. Because of the abundant vapor, the interior cave walls and the entrance way, are decorated with sulfur, calcite and gypsum crystals. The conditions in the cave are harsh and require safety equipment for exploration. The water vapor and liquid in the cave is highly acidic (thought to be sulfuric acid based on the damage done to cotton fibers), although water taken outside of the cave was near neutral. Photographs of the crystal-coated walls and underground stream were taken inside the cave. Water and microbe samples were collected both inside and outside of the cave. The microbial samples were prepared in the lab for DNA sequencing and water was analyzed in the field and laboratory. The results of sequencing the 16S rRNA gene has identified a community different from that of the neighboring Big Spring. The dominant species at WSS is Thiofaba tepidiphila, with, Chloroflexus sp, and smaller amounts of Sporobacterium sp, Flavobacterium sp, and Venenivibrio stagnispumantis.

The WSS cave appears to be formed along a crack in the travertine terraces, slightly off of vertical. The entrance is about 2-m high by ½-m wide, opens to about 1-m wide just inside the entrance, and runs only about 5 meters back into the rock face. In addition to the geobiochemistry, a resistivity study was conducted above the cave to determine its pathways of openings and water flow. The results of the resistivity study show a complicated system. Other geophysical methods will be deployed to assess the nature of this complexity.