The Grotto at Indian Head Cove EarthCache
Hidden : 1/10/2014
Difficulty:
2 out of 5
Terrain:
4.5 out of 5

Size: Size: other (other)

Join now to view geocache location details. It's free!

Watch

How Geocaching Works
Looking for a different adventure?

Please note Use of geocaching.com services is subject to the terms and conditions in our disclaimer.

Geocache Description:

This Earthcache, located in Bruce Peninsula National Park, was placed for the 10th anniversary of Earthcaching - January 10, 2014!

Please read the description and follow the instructions in order to be able to log your find !

Welcome to the steepest and deepest accessible point lining the shore of the Georgian Bay, and a favorite locale for swimming due to the crystal clear waters and flat rocky beaches. Indian Head Cove and its surroundings are the result of natural processes, carving out this inlet and other spectacular rocky formations in the region.

The Grotto, and with it, Indian Head Cove, were formed by constant waters swirling and hammering at this focal point between Lake Huron and the Georgian Bay, fiercely eroding away the mix of softer limestone and hardened dolomite that make up this ancient shoreline, uplifted and looking out over surrounding waters. It's the tip of a rocky cliff face reaching down to the deepest points of Georgian Bay, and looking out over the vast Canadian Shield to the north. A testament to a tumultuous geological period of Earth, and our own Canadian Shield's grand history.

Specifically, "The Grotto" is a cave hidden just to the west of the large rock beach at the cove, on the far side of an outcropping of rocks and cliffs which may require a bit of climbing and shambling to get over, and a pretty steep climb down to enter the cave itself - warranting the terrain rating. (Be sure to stop in and complete the nearby virtual GCG9X6 On Top of the Arch)

A few notes about accessing the Grotto:

  • Parking for the cove is now limited to time slots, available by reservation May 1-Oct 31 on a first-come first served basis, but the park is accessible year-round. See the Parking waypoint details for more information.
  • Note the terrain rating!
  • There are some easier routes around to the grotto, but:
    Please stay on any often-used trails and paths
  • This area is very popular during summer months for swimming, so if you hang around, please note:
    Cliff diving is strictly prohibited by park management!
  • The rocks and boulders in this area are mostly flat, but can be sharp and crop out randomly. Please be very careful as you traverse the beach, walls, and pathways in the area
  • Climbing down into the grotto, while popular, can be dangerous, so:
    Exercise caution and careful footing!
  • Finally, enjoy the adventure! :)

Down, down, down


The Grotto is located at the southern edge of the Main Channel which separates Georgian Bay from Lake Huron. Having endured thousands of years of waves eating away at the rock face, the Niagara Escarpment here forms a steep cliff that dips rapidly down to depths of 60m below water level within 100m of the shore line, and reaching a maximum depth of about 165m.

The Georgian Bay floor itself slopes upward from here to the east and north-east, just as its neighbour, Lake Huron, has the same downward westerly slope. Towards the eastern half of Georgian Bay, depths reduce to ranges from 25m often to less than 10m, with reefs and shoals forming a very rough bottom relief, as shown in the bathymetric maps above.

Crystal waters


With the constant bombardment of water here against the escarpment's lip of hard dolomitic limestone, the waters themselves are made crystal clear - some of the clearest water in the world - having visibility that easily reaches depths of 20-25m or more. Winds off the escarpment and currents in the area also cause upwelling - a churning of the waters near the shore due to prevailing winds that push surface waters away, pulling in colder water from below. Surface water temperatures can range from 0°C in January to 16°-19°C in August. This make the cove a very crystal clear, but chilly swimming destination!

Georgian Bay water levels have been recorded to vary as much as 2 meters, with its average chart datum sitting at 176m above sea level. This variation in water level can even be observed in places near the water surface on the lining rock wall.

Giant fishbowl


You're standing on the lip of a giant 'bowl' - the Niagara Escarpment. Here, the dolomitic limestone (dolostone) cap was formed as a sedimentary layer of Lake Huron, laid down during the existence of a thriving tropical sea in this region of Earth's history (within the period commonly known as the Ordovician-Silurian age). The Niagara Escarpment is the 'edge' of that tropical sea within the Huron basin, which could be likened to today's Great Barrier Reef. As the winds and waters deposited biologically-generated calcium carbonate and sediment, the limestone continued to build and mix with magnesium, hardening this shoreline. Erosion occurred as water levels receded over time, scraping the floor of the basin and producing drumlins (long tear-drop shaped 'hills') that scour both Lake Huron and Georgian Bay and much of the surrounding land mass even down to NW New York state. Erosion continues today over the vastly stretching dolostone lip of the escarpment, most notably at Niagara Falls, where the harder dolomitic caprock erodes slower than the rock below while the water traveling from the higher Lake Erie pours into Lake Ontario.



The Glacial Theory (click to enlarge)
The Glacial Theory holds that as the ice caps oscillated during the ice age in the direction indicated by the drumlins and basin relief, sub-glacial meltwaters eroded away much of the softer limestone sediment leaving the escarpment and current Huron basin as a remnant. Another theory employing tectonic motion holds that crustal uplift from the northeast - the vast Canadian Shield - caused flood waters and currents that were directed to the south and southwest, in the direction of the drumlins, enlarging the bluffs as scattered along the northeasterly shoreline of the Bruce Peninsula, but eventually directing the waters into the Huron basin through the lowest point of the escarpment, this Main Channel 'funnel' carved between the Bruce Peninsula and Manitoulin Island. This is where erosion was most intensified; focused here at the 'tip of the Bruce'.

The hungry bay eats away


The Grotto itself has been, and is still being, carved out of the ancient stone lining the shore, creating a beautiful geological formation with holes and tunnels both below and above the water level, and providing various smaller caves prime for exploring.

A big attraction to the grotto's natural cave is an underwater tunnel found below the Bay-side wall of the grotto. It's even visible while standing on the rocks just above the water inside the cave, as light from the other side glows through deep below. Only very skilled swimmers and divers dare attempt to swim under and navigate through that tunnel to the Georgian Bay.


In order to log this Earthcache...


Please complete the following tasks, and send me your answers using this form (please don't post your answers in your find log).
Please note: Find logs on the Earthcache not accompanied by answers submitted within a reasonable time frame may be deleted at my discretion.

  1. Reminder: Make sure you visit the actual grotto, which is about 30m west of the "Arch" location (the nearby Virtual). Many people get that far and seem to think that's the target. Don't make that mistake!
  2. Find a spot near the water's surface where you can make out rock that you think has been under water previously. Send me your estimate of difference in height of the current water level to the highest visible level, and a description of the rock's surface.
  3. Look into the clear water from above. How deep do you think you can see into the water right now? (note that objects in the water may appear closer than they are!)
  4. Estimate the height from the current water level to the top of the cave that forms the grotto. How high is the roof of the grotto above water?
  5. From inside the grotto, can you make out the entrance to the submerged tunnel?
  6. Enjoy the view! Have a swim! Take some photos, explore!
    (Photos are not required for logging, only for sharing of enjoyment :)
And finally, if you enjoyed this Earthcache, the first one I've published, please consider giving a favorite point :) Thanks!
----
Flag Counter
(since 7/30/15)

Additional Hints (Decrypt)

Cyrnfr or pnershy naq jngpu lbhe sbbgvat!

Decryption Key

A|B|C|D|E|F|G|H|I|J|K|L|M
-------------------------
N|O|P|Q|R|S|T|U|V|W|X|Y|Z

(letter above equals below, and vice versa)


Advertising with Us

Inventory

There are no Trackables in this cache.

View past Trackables

What are Trackable Items?

Bookmark Lists

View all 7 bookmark lists...