Welcome to the Underwater Caves of Rockwood! While paddling around the area, we discovered this beautiful series of small caves, with one larger cave you can explore further. Please remember to stay safe and only access the Earthcache when the weather and water conditions are safe to do so.
A big thanks to res2100 for some of the geological info provided below.
The caves in Rockwood Conservation Area are another unique feature created by the runoff of the Wisconsin glacier. Within the conservation area you will find an extensive network of 12 solution caves, as well as a few smaller caves in the limestone bluffs. The erosion of sedimentary rock created this cave system when an underground stream flowed through the rock. The cave system is one of the most extensive systems found in Ontario and exhibits depositional features including stalactites, columns and flowstone.
History and Geology of the Rockwood Area
410 million years ago Rockwood had a tropical climate, similar to a rainforest. Rockwood and most of southern Ontario was covered by a tropical inland sea. Rockwood was located in a shallow part of the sea where there was a thriving coral reef. The coral grew into small underwater cliffs, trying to access the top of the water because it needed sunlight. When the water levels dropped, the top of the coral cliffs would die, creating a pourous surface in which sea-dwellin creatures, such as snails and clams, lived in once the water levels rose. Over millions of years, their shells piled up and hardened, eventually becoming the limestone cliffs that are up to 36 metres tall. From the posted coordinates, you will have a great vantage point of these limestone bluffs.
Fast forward a few million year... 11,000 to 16,000 years ago was the peak of the Ice Age in the area. Instead of being covered by a tropical sea, Rockwood was covered by the Wisconsin glacier that was a kilometre thick, and over 3000km wide. As it grew, the glacier worked like a bulldozer, smashing everything in its way .
10,000 years ago, the moderate climate began. Finally free of its heavy load of ice the earth’s crust began to rebound. This left bald limestone exposed for the first time in centuries, and water at Rockwood began to flow. This lead to the creation of many of the rock formations that are visible today, including this section of caves.
Cave formation begins when rainwater absorbs carbon dioxide as it falls through the atmosphere. This carbon dioxide causes the rainwater to become acidic, resulting in a chemical reaction. Rainwater is absorbed by the soil into the ground as it falls, and as it travels through the soil it absorbs more carbon dioxide. This changes the ground water to a weaker form of carbonic acid (H2O + CO2 = H2CO3). When the rainwater hits limestone or dolomite caves can form. The water reacts chemically with limestone and slowly a larger and larger space will form. This happens because the rocks are made of calcium carbonate (CaCO3). This is what you call chemical erosion. As the space becomes larger and larger the water can flow through, causing erosion of the limestone . Physical erosion washes away rock and sand. This is what makes a cave larger and forms an underground stream. Limestone continues to dissolve under the action of rainwater and groundwater charged with H2CO3 (carbonic acid) and naturally occurring organic acids. The dissolution process produces a distinctive landform known as karst, characterized by sinkholes, and underground drainage. Solutional caves in this landform—topography are often called karst caves. Finally over hundreds of thousands of years or even millions of years the cave is formed.
The above process of cave formation is how this particular cave has formed over time. However, with this particular cave, water is allowed to flow continuously. The formation of this cave, and the network of caves it connects to, continues to occur with the tides and changes of the water in the bottom part of this cave.
Now that you know how this cave got here, it's time to explore it!
In order to log this Earthcache, please send me via email or geocaching messenger, answers to the following questions. Email me the answers and then go ahead and log this earthcache. Feel free to post pictures too. I will contact you if there are any issues with your answers.
1. Based on the current water level, how high is the cave ceiling above your head? Do you have room to stand?
2. At the water level, what is the elevation inside of the cave? How does this differ from outside of the cave entrance?
3. Have a closer look at the Rock inside the cave. Describe the colour and texture. How does it compare to the rock on the outside of the cave? 4. Do you see any distinct fossils inside of the cave?
5. Do you think the cave is wider above or below the water line? Do you think the cave is larger or smaller than what can be seen? Why do you think that since?
6. Optional: post photos of your visit.
** Please note that there is a fee to enter Rockwood Conservation Area. See additional waypoints for entrance location.