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Experts Piece Together A Jigsaw Puzzle of Broken Gypsum at Mammoth Cave National Park


Cave restoration specialist Jim Hildredth works to piece back together shards of fragile gypsum broken off a passageway in Crystal Cave. NPS photos.

Piecing together a Jigsaw puzzle is challenging even when you have a picture to guide you. Imagine the challenge Jim Werker and Val Hildreth-Werker faced when they were confronted by 600 pounds of fragile gypsum pieces that they were tasked with putting back in place in a passageway in Mammoth Cave National Park's Crystal Cave.

This past fall the two matched up shard after shard after shard after shard of the crystalline cave formation that had been stolen from a mile-long section of passageway back in 1995 by three vandals. At the time, park law enforcement rangers had recovered 600 pounds of the gypsum.

Now, 14 years later, and with new methods they perfected, Jim, Val, and their helper, Doug Soroka, searched for just the right pieces of gypsum to match together and reattach to the walls. Val, a professional photographer, says piecing together gypsum formations is “like working a giant 3-D jigsaw puzzle from the inside out.”

The Werkers are seasoned cave restorers; Jim got his start in caves in the Guadalupe Mountains in 1978. Val began repairing formations when she and Jim met while caving in the 1990s. Together they have brought their skills to 200 caves, including New Mexico’s Carlsbad Caverns, Oregon Caves National Monument, and Arizona’s Kartchner Caverns. The couple literally wrote the book on cave restoration – Cave Conservation and Restoration describes innovative techniques to repair damaged formations. The Werkers were also the first to discover how to fix broken gypsum formations, a more difficult task than repairing stalactites and stalagmites.

Legendary cave explorer Floyd Collins discovered Crystal Cave in 1917. In January of 1925 he brought attention to the cave region when he became trapped in Sand Cave and died there.

Restoring the splendor of Crystal Cave is no walk in the park; gypsum is extremely brittle, making it difficult to handle.

“Crystal Cave is an enormous challenge for the Werkers,” said Rick Toomey, director of the Mammoth Cave International Center for Science and Learning. “Usually when they do cave restoration the pieces are in their original location. In this case, specimens were taken out, jumbled about, and bleached for sale.”

The restoration process is intricate and time-consuming. The team often puts in 8- to 10-hour days. They must find the matching pieces, glue them back together, and attach the finished product to the wall using stainless steel rods.

“The big thing is figuring out how to rig it so it will stay in place,” said Jim. “We use a lot of bungee cords and small clamps. It takes several days for the glue to set.”

Once the epoxy is dry it can withstand 50,000 pounds per square inch of pressure. Afterwards the seams and bolts are undetectable. The completed walls are even dusted with a loose powdering
of cave dirt so that the colors match.

“We’ll work on an area until we get tired, and then move on to a new area, which gives us a fresh perspective,” Jim added. “We walk a lot of miles in a day.”

“We get intimately involved in the process,” Val explained. “Sometimes I can just walk along the passage and see a piece and think, 'Aha!' I know where this goes.”

Crystal Cave has long been famous for its beautiful gypsum crusts and flowers. Now thanks to the skilled efforts of Jim, Val, and Doug it will also be known for gypsum restoration.


Wow, that must have been both fun and annoying at the same time! Anyway, congratulations for Jim and Val Hildreth-Werker, the cave is better looking now, I imagine.

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