Eau Claire Gorge EarthCache

The underlying bedrock in this region is part of the Canadian Shield which dates back to the Precambrian era some 4.5 billion years ago. Lying on top is a very thin layer of soil - thin due to the massive glaciers that scraped the topography of this area. Given the well-sealed underlying bedrock, very little water seeps into it, therefore numerous lakes and rivers can be found throughout this region. The Eau Claire Gorge is an excellent example of how this impermeable bedrock controls the flow of water and the resulting watersheds of the region (the Amable du Fond flows east into the Ottawa River finally joining the St. Lawrence River).

The Eau Claire Gorge and the Amable du Fond were shaped by two geologic events - faults and glaciers. Faults appeared hundreds of millions of years ago. As the earth's crust cracked it shifted and the rock along these fault lines moved and was subjected to much grinding and crushing. This resulted in splintered rock accumulating within the fault zone compared to the solid rock outside of the fault line. Now comes the action of glaciers. Between 78,000 and 10,000 years ago, much of Canada was covered in up to three kilometers of ice. As the glacier moved through the area, it dug deep into the fractured rock moving it out of the fault zone leaving behind the steep sided gorge through which the Amable du Fond flows.

Logging Requirements:

To log this Earthcache, perform the following tasks and determine the answers to the questions below. Email me your answers, DO NOT include them with your Found It log.

1. Go to the posted co-ordinates where you will find an information panel. In 1954, part of this area was flooded. What natural event caused this flooding?
   
   
2. Proceed to Reference Point 1 where you will see the Eau Claire Gorge. Record your elevation here. In the falls are some large boulders. How do you think they wound up in the river? The answer to this question is not on the information panel. (Hint: Think of expansion and contraction).
   
   
3. Proceed to Reference Point 2 and record your elevation. For the sake of argument, let's assume that it takes 10 years to erode 1 mm of the underlying bedrock. How long would it take to erode the bedrock from the elevation at Reference Point 1 to the elevation at Reference Point 2?
   
   
4. Below is a list of waterfall classes. To what class do these falls belong?
   
   
   • Block: Water descends from a relatively wide stream or river.
   • Cascade: Water descends a series of rock steps.
   • Cataract: A large, powerful waterfall.
   • Chute: A large quantity of water forced through a narrow, vertical passage.
   • Fan: Water spreads horizontally as it descends while remaining in contact with bedrock.
   • Frozen: Any waterfall which has some element of ice.
   • Horsetail: Descending water maintains some contact with bedrock.
   • Plunge: Water descends vertically, losing contact with the bedrock surface.
   • Punchbowl: Water descends in a constricted form and then spreads out in a wider pool.
   • Segmented: Distinctly separate flows of water form as it descends.
   • Tiered: Water drops in a series of distinct steps or falls.
   • Multi-step: A series of waterfalls one after another of roughly the same size each with its own sunken plunge pool.