This experience comes in Chapter 35 of this excellent novel. As a natural result of the increasingly sinister games that Cordelia and Carol play with Elaine, where she is regularly verbally and psychologically abused by them, the climax is reached when Cordelia throws Elaine's hat down into a very steep ravine and commands her to go and get it and bring it back up so she can "be forgiven." At the bottom Elaine, in reaching for the hat, breaks through the ice and as a result finds that she is soaked by freezing water and it is very difficult for her to get out and climb up the ravine again:
My head is filling with black sawdust; little specks of the darkness are getting in through my eyes. It's as if the snowflakes are black, the way white is black on a negative. The snow has changed to tiny pellets, more like sleet. It makes a rustling noise coming down through the branches, like the shifting and whispering of people in a crowded room who know they must be quiet.
What saves Elaine is hearing a voice of a woman who comes down to her and gives Elaine the hope and energy to get up and go home. Elaine beleives that this specteral figure is actually the Virgin Mary, but either way she manages to get up and climb up the ravine again and reach the top, where she meets her mother.