From the text:
But he knew also that there were streams of water that came out from the hillsides and ran along under the snow and on top of the ice of the creek. He knew that even in the coldest weather these streams were never frozen, and he also knew their danger. 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 was both water and thin ice, and when a man broke
through he could get very wet.
Frost bite
When all was ready, the man reached in his pocket for the second piece of tree bark. He knew the bark was there, although he could not feel it with his fingers. He tried again and again, but he could not.
And all the time, in his mind, he knew that each instant his feet were freezing. This thought alarmed him, but he fought against it
and kept calm.
He pulled on his mittens with his teeth, and began swinging his arms. Then he beat his hands with all his strength against his sides.