The rocks that caves are found in.

Photos I have taken of caves.  From top left:  Writing-on-Stone Provincial Park,
Drumheller, West Coast Trail (Vancouver Island), Zion National Park.

As a boy, I had a fascination with caves.  I had books on them and watched shows on them (National Geographic specials were the best), but had never actually seen one.  Then, in grade 11, we did a field trip to a limestone cave.  Truthfully, it wasn't much, but it was still cool, and it fueled my desire to see more.

Limestone is the rock we all point to when considering where these voids exist.  Limestone is a sedimentary rock and has horizontal layers, but vertical cracks also form between them.  Water, always searching for a lower point, finds its way through these bedding planes and fissures, chemically dissolving small amounts along its way.  Over time, the hollow spaces expand.  Eventually, the system of  caverns may extend for hundreds of miles.  

Limestone isn't the only rock caves can be found in though.  The pounding surf takes erosion to another level as shoreline cliff faces are carved out of the bedrock.  The rock itself can be of almost any form; nothing can withstand the sea for long.  Basalt is perhaps the most common as the hydropneumatic action blasts bits away with each onslaught.  

Moving water is also the force at hand when carving sandstone.  The friable rock is eroded a bit at a time, often down vertically but also into the sides of cliff faces.  If it gets in far enough, the face will eventually collapse.  Such is the nature of caves; they are all ephemeral.  No cave is forever.  But while they are here, they are great places to explore.

Below, I am including a photo I took of caves on the island of Tasmania.

Kathryn in Hobart Hasting Cave in Tasmania, Australia, in 2018.

Thanks for reading.  

Eric Svendsen     www.ericspix.com


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