In "To Build a Fire," why were the creeks particularly dangerous?
The omniscient third-person narrator of Jack London's "To Build a Fire" explains why the area around the creeks were particularly dangerous, although the creeks themselves were frozen solid.
The creek he knew was frozen clear to the bottom—no creek could contain water in that arctic winter—but he knew also that there were springs that bubbled out from the hillsides and ran along under the snow and on top the ice of the creek. He knew that the coldest snaps never froze these springs, and he knew likewise their danger. They were traps. They hid pools of water under the snow that might be three inches deep, or three feet. Sometimes a skin of ice half an inch thick covered them, and in turn was covered by the snow. Sometimes there were alternate layers of water and ice-skin, so that when one broke through he kept on breaking through, for a while, sometimes wetting himself to the waist.
If a man got soaked when it was seventy-five degrees below zero, he would have to build a fire immediately because the water would all turn to ice and cause severe, if not fatal, frostbite. The protagonist is afraid of these "traps" but apparently he has to keep close the creek because that is where the trail is. He couldn't walk through the snow parallel to the trail because it was too deep. Eventually the man breaks through the snow at a place where he least suspects it. He wets himself halfway to his knees. He is not frightened yet, but very much annoyed because he will have to build another fire immediately and dry out. This will delay him for at least an hour, and he is anxious to get to his destination, where he will have warmth, food, and companionship. He certainly does not want to be traveling on foot in the dark. This is where his troubles really begin. He makes the bad mistake of building his fire under a spruce tree that is loaded with snow from the bottom branches all the way up to the top. All his activity in getting fuel under the tree causes just enough agitation to the snow-laden branches to create an avalanche which covers him with snow and completely obliterates his fire.