On the western side of the continent rises gradually from the Polar regions the mighty chain which runs throughout its whole length--a distance of altogether 10,000 miles. The northern portion, known as the Rocky Mountains, runs for 3000 miles, in two parallel chains, to the plains of Mexico, flanked by two other parallel ranges on the west,--the most northern of which are the Sea Alps of the north-west coast, and on the southern, the mountains of California. At the north-western end of the Sea Alps rises the lofty mountain of Mount Elias, 17,000 feet in height--the highest mountain in North America--not far from Behring Bay; while another range, the Chippewayan, stretches eastward, culminating in Mount Brown, 10,000 feet in height, and gradually diminishing, till it sinks into insignificance towards the Arctic Circle. Point Barrow is the most northern point of America on the western side. It consists of a long narrow spit, composed of gravel and loose sand, which the pressure of the ice has forced up into numerous masses, having the appearance of rocks. From this point eastward to the mouth of the Mackenzie River the coast declines a little south of east. The various mountain ranges existing on the eastern side of the continent, including the chain of the Alleghanies, form what is called the Appalachian system. It consists of numerous parallel chains, some of which form detached ridges, the whole running from the north-east to the south-west, and it extends about 1200 miles in length--from Maine to Alabama. Besides the Alleghany Mountains in the western part of Virginia and the central parts of Pennsylvania, it embraces the Catskill Mountains in the State of New York, the Green Mountains in the State of Vermont, the highlands eastward of the Hudson River, and the White Mountains in New Hampshire. Mount Washington, which rises to an elevation of 6634 feet out of the last-named range, is the highest peak, of the whole system. To the north of the Saint Lawrence the lofty range of the Wotchish Mountains extends towards the coast of Labrador; while the whole region west and north of that river and the great Canadian lakes is of considerable length, the best-known range being that which contains the Lacloche Mountains, which appear to the north of Lake Huron, and extend towards the Ottawa River. These two great ranges of mountains divide the North American continent into three portions. GREAT RIVERS.