33GLACIERS, DIRT, AND THE SYDENHAM RIVER

Why does the land look the way it does? Why do we have sandy soil in one place, and clay soil in another? The answer is geology.

The Sydenham River at Tupperville.
The Sydenham River at Tupperville.
350 million years ago, shale and sandstone bedrock was formed. Bedrock is deep below the planet's surface and covered by clay, till, sand and gravel. It is rare to be able to see the bedrock layer, but at Shetland and Alvinston, erosion has exposed this rock. In fact, an outcrop of bedrock upstream of Shetland created Smith Falls, the only falls in the Sydenham River. The bedrock layer is actually deeper below the surface in the western Sydenham River basin (152 meters above sea level) and shallower in the eastern portion of the basin (220 meters above sea level).

Where did this glacier come from? The Wisconsin glacier grew outward from the Northwest Territories, Labrador and northern Quebec. The movement of glaciers over land is a lot like the way a spoonful of pancake batter spreads out when it is poured into a frying pan. Ice sheets move forward by cooling (advancing) and backward by melting (retreating).

page 1 of 4 next page>