Continental Divide

The Continental Divide trends roughly north-south through the United States along the backbone of the Rocky Mountains. It divides the country into watersheds emptying westward into the Pacific Ocean or eastward into the Atlantic Ocean or the Gulf of Mexico.

One would think that extension of the Continental Divide into Alaska would bring it along the lofty Alaska Range and across Mt. McKinley. Instead, as the map shows, the Continental Divide through Alaska runs along the Brooks Range and into Seward Peninsula where it terminates at Cape Prince of Wales. Thus it separates the watersheds draining north and west into the Arctic Ocean from those draining west and south into Bering Sea.

The curious track of the Continental Divide from the Rockies into the Brooks Range led geologists until recently to assume erroneously that the Brooks Range was a structural extension of the Rocky Mountains. But just within recent years geologists have determined that the Brooks Range was uplifted about 100-200 million years ago, sometime earlier than the uplift of the Rockies, 65 million years ago. So now, most geologists think that the Brooks Range is not structurally related to the Rocky Mountains. Nor is the Alaska Range. It has been formed very recently, within the last 5 million years, and is still rising.