With George Washington into the Wilderness by Edwin L. Sabin

Christopher Gist hurried on. When the Hunter arrived, the two were gazing perplexed; and no wonder.

Here lay the swift Allegheny River, a quarter of a mile wide, but it was not frozen over. It was frozen for only fifty paces out from either bank. All the space between the borders was black current, in which great ice cakes, borne rapidly, churned and swirled on their way to the Forks below.