earthstory:Parc National de la Jacques Cartier This river, the Jacques-Cartier River in Quebec, Ca
earthstory: Parc National de la Jacques Cartier This river, the Jacques-Cartier River in Quebec, Canada, drains an area north of Quebec City into the St. Lawrence River and eventually to the Atlantic. The shape of this river valley is distinctively glacial. When rivers erode downwards to create canyons, they typically leave the walls surrounding them at or near the angle of repose – the angle where if rocks are too steep they break off and fall as rockfalls or avalanches. River-carved valleys therefore have a characteristic “V-shape” with the river at the bottom of the V and walls at or near the angle of repose. Geologic units of differing strength can disrupt this pattern somewhat, but it holds impressively well. さらに読む -- source link