Toronto's Double Ice Age Earthcache EarthCache
Toronto's Double Ice Age Earthcache
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A historical brick works site; a Farmers’ Market; a finalist in National Geographic’s Geotourism Challenge 2009; wetlands, woodlands, and a wildflower meadow that are home to wildlife including great blue herons, raccoons, and opossums; and an internationally significant geological site……all in one 16-hectare public park less than 4 kilometres from Toronto’s City Hall!
This Earthcache will take you back million of years to the site of an ancient tropical sea. Fast forward to relatively modern times when a clay quarry to make bricks was founded in the 1880’s. In 1894, University of Toronto geology professor A.P. Coleman made a discovery of international significance at this site – in the North quarry wall, he found fossil evidence of two full-blown ice ages. This is one of the very few sites in the world where climate change can be studied between the last two major glaciations.
Evidence from the Illinoian Glaciation (~135,000 years ago) can be found at the bottom of the North Slope. Above this is the Don Formation (~125,000 years ago) - fossils here suggest that Toronto's climate at that time was slightly warmer than at present. From fossils in the next two layers (Scarborough and Pottery Road Foundations ~110,000-80,000 years ago), there is evidence of a cooler climate, leading up to the Wisconsin Glaciation (~50,000-13,000 years ago).
To read more about the formation of the different layers of the North Slope and to see fossils found in this area, visit this link: (visit link)
The posted coordinates will take you to the North Slope of the old quarry wall. Here, you will find a plaque with a diagram of the geology of the area to help you out. After visiting the North Slope, continue South-West along the path to N43 41.234, W079 22.030 where there is a similar plaque - on this route, you will pass the West Wall on your right-hand side.
To log this cache as “Found”, please perform the following tasks and email your answers to the CO:
1] Measure or estimate the height of the North Slope.
2] Estimate how many metres in height are represented by the Wisconsin Glaciation.
3] Compare the geology of the Illinoian Glaciation to that of the Wisconsin Glaciation - find at least two differences. (Hint: geology of the West Wall is indicative of that of the Illinois Glaciation.)
4] Compare the vegetation near the bottom of the North Slope to the vegetation at the top of the North Slope. Do you see any differences?
As the Brick Works is home to many fauna and flora, include in your posted log any interesting wildlife you may have seen along your path through the Brick Works.
Additional Hints
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