"I thought," he said tightly, peeling bark from his beard, "we were going to stop when we hit snow."
Elizabeth explained. Usually, when we hit snow, it's passable for a while, and then it suddenly gets too deep to traverse, and that's when we were going to turn back. This snow, however, had remained thin, albeit slick. "So," Dave said, "what you meant was, we would go until the snow was in fact impassable, and at that point we would not continue passing. We would not, as you say, violate any laws of physics. Is that it?" Shluck shluck shluck SHLOOOORP bink-bink-bink-bink-BAM.
"Right," Elizabeth said. "You okay?" she called down.
"Next time," Dave said, "snow means snow."