Wednesday, May 28, 2014

Ontario's Largest Natural Cavern

A little to the west of the intersection of Harmony Road and Shannonville Road in southern Hastings county lies the home of Ontario's largest natural cavern.

The story of Tyendinaga Cavern and Caves dates back to the Paleozoic Era during the Ordovician Period, when what is today's karst topography once formed the beds of ancient seas some 490 million to 440 million years ago. Fossil remains of the sea life can be found in the rocks surrounding the caves, and visitors are treated to mural painted by Elizabeth Koch and Ildiko Olive depicting their interpretation of the living animals. It's a shame there were background reflections and glare because the photograph really doesn't do the painting justice.

A mounted display of the smaller fossils and cave formations.

Much as they do today, sponges and corals thrived in the warm, shallow seas of this epoch.

A sponge shares this piece of limestone with a few smaller nautiloid shells. The Ordovician was the heyday of the Cephalopods and the remains of nautiloids and ammonites – distant cousins our modern octopuses and squids – abound in the limestone, attesting to their former numbers and diversity.

These ammonite shells are about 50 cm in diameter.

The mold or impression of a much larger nautiloid shell. The cast in the next image is a good healthy meter long.

Calcium carbonate has crystallized as calcite inside this nautiloid fossil.

Some aptly named honeycomb coral.

The fossilized "stem" of a Crinoid. Also know by the misleading name of Sea Lily, these were (and still are, although relatively uncommon) actually sessile animals belonging to the phylum Echinodermata, related to starfish, sea urchins and sand dollars.

And this fossil is a mystery ... could it possibly be the remains of some primitive vertebrate?

Elizabeth explains the formation of flowstone before we move on to tour the caves and their associated topography.

The caves are estimated to be about a hundred thousand years old – a mere geological blink of an eye – and the periods of glaciation (there were more than one) during this time were a force of both creation and destruction. Vast amounts of meltwater from the retreating ice would carve its way through the soft limestone forming caverns, only for them to by crushed by the weight of another advance of the ice and forming rubble filled sinkholes.

The Water Cave – the water level can rise rapidly during heavy rainfall.

The Hourglass Cave, so called because of its shape; a symbol of time is apropos considering the lengthy spans involved in the formation of the caves.

And here we are at the main attraction, on the other side of the doors are about a hundred meters of underground passages to explore.

Look up, waaaayyy up ... and I did, searching for – but not finding any – cliff-loving ferns with a preference for a basic substrate, such as Cliffbrakes or Wall Rues.

The caves are constantly changing and evolving, with mineral rich water continously seeping in and depositing calcium carbonate and creating formations called, appropriately enough, flowstone.

A rather eerie looking accumulation of flowstone.

Calcium carbonate left behind by water dripping from the cave ceiling forms the feature most people associate with caves – stalactites. Some of these are straw stalactites, so called because they are hollow. The bright spots at their tips are reflections of the camera's flash reflected from drops of water. We were invited to return in another thousand years or so, by which time the stalactites would attain a length of six or eight inches ... I can hardly wait ...

Water takes the shortest path, which isn't necessarily a vertical one, forming these fascinating deposits called cave curtains.

The pair of accretions to the left in this picture resemble a pair of dentures.

I neglected to ask (or have forgotten) what process shaped these intriguing little cave mushrooms. The "buttons" on their ends are wider than their "stems", and they can occur on walls that aren't vertical.

This passage is open to the public, but it's for advanced spelunkers only. No worries if you lose your grip on the walls whilst negotiating this crevice, you'll be wedged in tightly long before you hit the bottom an estimated 17 meters to 25 meters below.

Another tight squeeze, but somewhat more comfortable – on a mental level if not physically – to squeeze through knowing one's feet were on terra firma.

Calcium carbonate deposited by water seeping through the tiniest cracks and crevices continues to seal the cave with the passage of time. At this point the ceiling is more than seven meters above our heads and we're nearly twelve meters below the surface.

Ever wonder why our planet is sometimes called "Mother Earth"?

The walls bear dates left by passersby who stopped for shelter, or perhaps evading the long arm of the law, there's one inscription dated 1812. But no one left other than their initials at most, including the artist who created this cute little sketch. Could this be a "selfie", so to speak? There are still unknown and unexplored passageways down there in the nethermost bowels of the earth ... is it possible the caves are inhabited by a colony of Kobolds?

In addition to any hypothetical "little people", Tyendinaga Cavern and Caves is home to the Big Brown Bat, the Little Brown Bat and the Eastern Pipistrelle – and an arachnid affectionately nick-named "Charlotte".

Looking at her from a distance I mistakenly thought Charlotte might be a Charlie, because it seemed that she had the enlarged palps characteristic of male spiders (some photos of a male Meta ovalis). But zooming in on the photos on the computer established that the palps were actually her lunch and the spider is indeed a female. But now I wonder exactly what small denizen of the caves she is eating?

Despite the temperatures (supposedly 10° C give or take, but it sure felt cooler than that) a tiny worm was crawling up the cave wall. Will it get encrusted in the calcium carbonate and be fossilized, to be found by future alien paleontologists millions of years from now? Only time will tell, but since we're talking about time as measured in terms of geology where change often happens at a worm's pace ... we'll never know ...