Original sentence: The Canadian Rockies form a major continental divide in Canada.The Columbia and the Fraser Rivers have their headwaters in the Rockies and are the second and third largest rivers respectively to drain to the west coast of North America
Edited sentence: The Canadian Rockies form the continental divide in Canada.The mighty Columbia and the Fraser Rivers have their headwaters in the Rockies and are the second and third largest rivers respectively to drain to the west coast of North America