Everyone knows that Grant’s Cathedral Caverns is a treasure, a fun-to-visit underground world where you can get a look at one-of-a-kind cave formations. It’s one of Marshall County’s major tourist attractions.
But for the last decade or so, some pretty serious science has been taking place in the cave as well, off the beaten paths, in parts of the cave tourists seldom get to visit that are far beyond the end of the trail. Students from the University of Alabama’s Department of Geological Sciences have been studying the cave and formations within under the direction of Dr. Joe Lambert.
They’re looking at “paleo” or prehistoric rainfall records as archived in the cave’s stalagmites, with an eye towards seeing how wetter/dryer-than-usual weather might have affected the rock record.
Dr. Lambert recently led a private tour of the cave for the spring meeting of the university’s Geological Sciences Advisory Board. The GSAB is a group of alumni and friends of the department who provide the little extras for that specific department. They’ve given over $500,000 in scholarships to UA geology students over the last 20 years. Their spring meeting was at Lake Guntersville State Park, with the tour of the cave following.
Dr. Lambert began the tour by telling how it all got started. A former endowed chair (Loper Chair) of the department was awarded a National Science Foundation grant to study paleo monsoon records on an island (Niue) in the Pacific Ocean.
“We thought we probably ought to do some work closer to home to get some ideas of how to approach that specific type of research before a team went to the South Pacific,” Dr. Lambert said. So they started with similar research in DeSoto Caverns. That in turn led to the work at Cathedral so they could see if what had happened geologically in Cathedral was similar to what they’d seen in Desoto.
The work has been particularly good for the students in the geology program.
“We’ve had two doctoral dissertations and three master’s thesis come out of the research at DeSoto Caverns,” Dr. Lambert said.
The field work in Grant was all done Tuesday through Saturday, Dr. Lambert said, and that was very purposeful. He grew up in Cullman and the reason he didn’t lead student expeditions in the cave on Mondays was because Johnny’s BBQ in Cullman was not open on Mondays. He liked to stop at Johnny’s on the return trip to Tuscaloosa from Grant.
The studies have looked at all kinds of factors that might have influenced cave formation growth – relative humidity, drip rates, the amount of carbon dioxide in the cave air, etc. A couple of small formations off the beaten track were taken for further lab analysis.
You can slice through a stalagmite and count the rings just like you count rings on a tree to gain some information regarding the age for the formation. But there’s a better way to do it with state-of-the-art analytical equipment in the laboratory setting. Trace amounts of uranium are deposited in cave formations from the drips. U-series dating can be used to get a better idea of the age of the layers that make up a cave formation.
The research has included recording drip rates by placing a battery powered instrument, cleverly named a Stalagmate, beneath drips that counts the rates.
“These devices will stay powered up for years,” Dr. Lambert said.
Some drips are “old faithfuls,” slow and very steady. Others drip rapidly or quit dripping altogether in a time of dry weather.
Students – and the GSAB – also enjoyed seeing fossils in the cave, just like the tourists. They also looked at the shark teeth embedded in the ceiling.
Dr. Lambert pointed out that the alignment of Cathedral Caverns is actually pretty remarkable. In some other caves, you have to go down, down, down to access the cave. Cathedral is actually very horizontal right in the side of a mountain.
Goliath – the world’s largest cave column – still stuns as it always does. It’s one of Cathedral’s most beloved features.
“Just about every cave you enter will have some world records and this is one of Cathedral’s,” Dr. Lambert said.
Just beyond Goliath is another of Cathedral’s most beloved features – the Frozen Waterfall. Water was really flowing over the Frozen Waterfall on the tour and one of the scientists commented on it.
“It’s flowing so fast because there’s a recirculating pump in it,” Dr. Lambert said with a grin.
Many of the cave’s most distinctive features have water pools that reflect the feature. They’re all manmade. Dr. Lambert said there’s very little naturally standing water in the cave.
Much of the work of the University of Alabama students took place in “The Crystal Room” well beyond the bounds of the regular path and tour. Dr. Lambert also gave some insight into why it’s called “The Crystal Room.”
There are no actual crystals in it. But the many formations are delicate.
“You know how a singer with a high-pitched voice can break glass?” Dr. Lambert said. “It’s said that if that singer were singing in that room, it would break the formations like crystal.”
Dr. Lambert – a former college baseball player – is not a small guy. But he led most of the student expeditions to the back of the cave. It required going over the rail at the end of the main trail, scrambling down a rip-rap like boulder canyon, then carefully maneuvering the unlit depths of the cave.
The trek requires head lamps, helmets and knee pads.
“You never go or come the same way because of the ruggedness,” he said.
He added that the students would always “book it” in the developed part of the cave, then make the perilous trek into the far reaches of the cave. No one got injured during the research, other than the odd scrape and sore muscle afterwards.
A few findings from the research are:
• Differences in the size of microscopic crystals that form in stalagmites during winter vs. summer can cause visible couples, or bands, similar to trees.
• Every drip in a cave is different due to the different paths water travels through the bedrock above. The device used to record drip rates is playfully named a “Stalagmate®.”
• When groundwater emerges from the cave ceiling, dissolved bicarbonate and calcium ions form solid calcium carbonate, resulting in the cave formations (or speleothems) we see today. The process releases carbon dioxide into the cave’s atmosphere and produces a small amount of water.
• Rainfall amount and chemistry change seasonally and annually.
• The chemical composition of cave water is affected by the chemistry of the rainfall as well as the water’s interaction with the bedrock through which is passes. Changes in the chemistry of the water are often passed on to the minerals. By studying the chemistry of present-day cave waters and calcite deposition, we can make interpretations about past rainfall patterns based on the chemistry of much older calcite.
Most of the active research ended in 2019, although Dr. Lambert said if he were to have a master’s-level student, he would not be averse to starting it back up.
(Note: Dr. Joe Lambert is a close personal friend of the author. They hunt and fish together whenever they get the chance.)
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