The town of Cobalt is located approximately 150 km north of North Bay, Ontario. It is world-renowned for its silver mining history in the early 20th century. But, little known to many except locals, it also possesses a unique geological feature south of town on Highway 11B known as a whaleback or rock drumlin.
At the posted co-ordinates, you will see the trailing end of the whaleback adjacent to the highway. (Ample parking is available on the wide road shoulder but beware of swift traffic.) Follow the short path until you see more of this phenomenon looming in front of you. Continue hiking on top of the whaleback for several hundred metres but BE VERY CAREFUL WHEN THE SURFACE IS WET OR ICY as it can be extremely slippery. Alternately, you can opt to walk along side of the whale.
WHAT are WHALEBACKS?
Whalebacks are elongated, smoothed bedrock bumps and are approximately symmetrical, looking like the backs of whales breaking the ocean surface. Rock drumlins are asymmetrical with steeper faces and gently tapering lee sides.
According to some research, whalebacks can form below ice a few hundred metres thick but are best developed where the ice is 1-2 kilometres in depth. Whalebacks up to 1 km long have been noted in the Coast Mountains of British Columbia.
FORMATION of WHALEBACKS
LOCAL HISTORY and CACHE LOGGING
This impressive whaleback has been the focus of many local geology classes over the years. There have also been 2 traditional geocaches here in the past (GCG1WC ""The Mile Rock Walk"" by paragon and GC33AE7 "The Mile Rock Walk 2" by Robo-Jack)
In order to log this cache as "found", you will need to answer and e-mail me the answers to the following questions:
a) This whaleback is oriented generally north-south. Which direction did the glacier responsible for its creation move? northward or southward?;
b) Were there any visible striations or gouges along the length of the whaleback?;
c) Estimate the width and height of the whaleback at its point of maximum emergence above ground level;
d) Based on your research, would you define this landform as a "whaleback" or a "rock drumlin"; and
e) Feel free to post any photos of your experience along with your log.
After e-mailing me your answers, go ahead and log your "find". I will contact you if there are any issues with your response.
Thank you for visiting this EarthCache and taking the time to learn about whalebacks and rock drumlins.
