Understanding the Geology of Caves and Karst Topography

With the predominance of limestone in the Rockies, various caverns and caves have been eroded. Castleguard Cave is the most famous of these. It has been mapped for more than 17 km (11 miles)  under the Columbia Icefields, making it the largest cave system in Canada.

Near Canmore, Alberta, the Rat's Nest Cave on Grotto Mountain provides an excellent example of the many formations found in local caves. Formed by the slow dissolving of the limestone, these caverns form what may have been an important drainage channel at various points in history. In fact, the Castleguard Cave still floods every spring making it a dangerous cave to explore, prompting the Canadian Parks Service to close it off to all but specially approved expeditions. The Rat's Nest cave has also been recently protected by the provincial government and access is now restricted. This is not as much for the danger of exploring but more to protect the unique features present in this cave.

Formed many thousands of years ago, it has had sufficient time to produce spectacular stalactites and stalagmites in addition to many other formations. Stalactites are the icicle like formations hanging from the roof of caves and form by the constant dripping of water laden with dissolved minerals. The minerals deposit on the stalactite, and it slowly grows towards the floor of the cave. Often directly below it, a stalagmite will be growing upward in the same fashion.

Also interesting are the soda straws that often line the caves roof. Like delicate crystalline straws, these formations are also caused by the constant dripping of water Just before a water droplet releases, it is hollow. Magically, the deposits of minerals left behind may reflect this as the hollow droplets add tiny additions onto the length of the straw, allowing it to slowly extend downward towards the floor of the cavern. These incredibly brittle straws can be almost as thin as a plastic drinking straw, and shatter at the slightest touch.

In some of the caverns, the walls are constantly wet from flowing water, and have resulted in cauliflower formations – smooth, wet, brownish deposits that actually resemble a brownish form of its namesake.

Further into the cave, are found some of the most exciting discoveries – cave pearls. Tiny, perfectly formed pearls of Calcium Carbonate (the same chemical that makes up limestone), they are formed under water, in shallow pools. As you look at the pearls, they seem to form in tiny groups of pearls all the same size. They almost resemble tiny nests of eggs swirling around as each drop of water falls into the pool.

Adding to the geologic value of the cave are a number of biological discoveries. To enter one of the caverns one must crawl down through a tiny whole excavated through wall of bones and gravel. The wall is approximately four feet deep and inside the cave is found a number of bighorn sheep and bear skulls. Also, as one explores the cave, very old bat skeletons can be found including one mummified skeleton near the first set of cave pearls.

Although caves are wet and cramped, they can provide an exciting area to both study and explore. Remember though, that these formations are very fragile, and in some cases, permission must be obtained before entering.

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All Material © Ward Cameron 2005