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A bubble dripping on the right, ordinary soda-straw drips on the left. NPS Photo/G. Baker
The temperature and humidity inside Lehman Caves, in Great Basin National Park, hardly change through the year — but the amount of water does. Each spring, as snow melts above the cave, water seeps down through the epikarst and drips into the cave. Most of it runs down soda straws, stalactites, draperies and flowstone, leaving a little calcite behind and making them grow.
Sometimes it does something stranger. In the very wet spring of 2023, a few soda straws had bubbles on their tips. Bubbles had been seen before, but nobody had recorded how long they lasted, how fast they dripped or where they formed — so park ecologist and cave specialist Gretchen Baker set out to measure them.
Why bubbles matter here
Lehman Caves has more than 1,000 documented turnip stalactites — probably twice that in all — an unusual formation found in few other caves. Broken ones, including one on display in the Lehman Caves Visitor Center, show layers of calcite like an onion. One idea is that they form where a bubble stays put long enough for calcite to build up around it.
The count
| Where | Depth | What was found |
|---|---|---|
| Lodge Room | about 110 ft (30 m) — water arrives within days to a couple of weeks of warm spring weather or big summer storms | March 23: five bubbles, dripping every 0.8 to 2.9 seconds. March 24: four of the five still dripping. March 25: three of the originals plus a new one. Over 14 visits, some bubbles kept coming back — two appeared nine times. 16 bubbles in all, the last two on April 20 |
| Inscription Room | about 140 ft (40 m) | one bubble on April 14, then nothing |
| Cypress Swamp | about 140 ft (40 m) | 10 bubbles on April 17, lasting until about May 4 |
Bubbles seen on each visit to Lehman Caves, spring 2023, in the Lodge Room, Inscription Room and Cypress Swamp. Days with none are days the cave was not visited. NPS
Some of the Cypress Swamp bubbles behaved oddly. One would drip several times, vanish, reappear and drip again, over and over. Another spouted water from its bubble, then stopped and disappeared, then started again.
Still a mystery
What makes the bubbles — carbon dioxide? microbes? Nobody knows. And do they make turnip stalactites? The bubbles seen in 2023 and in earlier years don't seem to last long enough for calcite to form around them, so the turnips may have grown when the cave's climate was different. The plan: watch for bubbles again the next spring, and learn more.
Sources
Based on "What's Dripping in the Cave?" by Gretchen Baker, Ecologist/Cave Specialist, first published in The Midden, Great Basin National Park, volume 23, number 2 (Winter 2023), National Park Service; a work of the United States government in the public domain.
В изданияхGreat Basin National ParkThe Midden - Great Basin National Park: Vol. 23, No. 2, Winter 2023
Лицензия: CC0 1.0 (общественное достояние) · По материалам www.nps.gov
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