The Breakup of a River.
In the winter wilds, rivers are the only roads. Once the coldest part of the winter is past, the threat of breakup is always present and if it comes when the sled teams are still far from anywhere, it can spell disaster.
Desperate to beat the breakup, we traveled day and night.
Four factors contribute to the breakup of a river.
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Temperatures rise, softening the ice, which therefore breaks more easily. The snow on exposed slopes melts, and the water flows onto the river ice, increasing pressure. During the winter, a space was created between the ice and the water, which also weakens the surface. And of course there is the current.
In some cases the snow is so deep that even with snowshoes it cannot be packed down enough for the dogs and sled to pass over it. Progress then becomes extremely difficult.
A porcupine is a ball of needles. When approached by a dog, the porcupine whips its tail around, sending quills into the dog's face.
If they are not removed quickly, the dog will die.