The surface of Earth's land masses are a mosaic of watersheds, each representing the area drained by a given river and its many tributaries. Our planet's largest rivers, such as the Nile, the Amazon and the Mississippi, have massive watersheds but each is composed of smaller watersheds, drained by the feeder streams. The Mississippi watershed, for instance, encompasses those of the Red, the Arkansas, the Ohio, the Missouri, the Illinois and the Minnesota Rivers, to name but a few. In turn, the watersheds of these tributaries have numerous component watersheds; the Missouri watershed, for example, includes those of the Osage, Kansas, Sioux and Yellowstone Rivers, among many others. Indeed, even the smallest streams and creeks have watersheds; our home in Columbia lies within the Flat Branch watershed, which feeds Hinkson Creek, which is a tributary of Perche Creek, which enters the Missouri southwest of town.
Divides are the lines of high ground that separate watersheds. While the high spine of the Continental Divide offers a prime example, separating the watersheds that empty into the Pacific from those that flow toward the Atlantic, there are divides in every part of every country. Even the Great Plains Province, characterized by relatively flat terrain, harbors numerous divides that mark the boundaries between the watersheds of its meandering streams.
Avid hikers, explorers and cartographers have long had an interest in watersheds and divides. The topography of any given region is, after all, the product of numerous streams acting upon the underlying geology. To truly appreciate a landscape, one must understand the composition of its bedrock and the pattern of rivers that have shaped its ridges and valleys.