When authors refer to other great works, people, and events, it’s usually not accidental. Put on your super-sleuth hat and figure out why.
The Great Crossing a.k.a. The Great Westering refers to the time when a brave lot of people moved west into uncharted territories. Many bands of explorers set out to see what America had to offer and when they finally reached California, they settled down. Grandfather was the leader of one of these groups (fictional, of course) and he has been reliving the adventuresome experience ever since.