Page:Popular Science Monthly Volume 23.djvu/535

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DISTRIBUTION OF NORTH AMERICAN FORESTS.

It will perhaps be best to describe the provinces briefly:

The Lacustrine province extends from the Rocky Mountains east to the coast of Labrador, and from the northern limit of trees south to latitude 42° at or near the level of the sea. The line marking the southern boundary curves gradually from west to northwest; commencing at the west end of Lake Erie, on reaching Lake Winnipeg it pursues a northwestern direction to the base of the Rocky Mountains about latitude 60°.

The Appalachian province comprises the Atlantic States south of latitude 43° and east of the border of the prairies; the latter, commencing at the west end of Lake Erie, forms a curve nearly parallel to the Atlantic coast, and ends at the southwest corner of Louisiana.

The Campestrian province commences at latitude 60° in the Rocky Mountains; its northern boundary extends southeast to Lake Erie; its eastern boundary extends from the latter point south to the mouth of the Sabine River. The valley of the Rio Grande forms the southern boundary. The western boundary is formed by the base of the Rocky Mountains, extending northwest from longitude 104° 30' to latitude 60°.

The Rocky Mountain province embraces the high central mountains from the Campestrian province to the foot-hills of the Cascade and Sierra Nevada Mountains.

The Caurine province begins at the northern limit of trees, on the Pacific coast, and extends east to the western boundaries of the Lacustrine and Campestrian provinces. Its southern boundary begins at latitude 48°, on a southern extension of the western boundary of the Campestrian province, extends northwest to the British line at its junction with the line between Washington and Idaho Territories, thence south to latitude 42°, and then southwest to the Pacific Ocean at latitude 38°.

The Nevadian province lies south of the Caurine, between the Rocky Mountain province and the Pacific Ocean.

The Mexican province lies south of the Rocky Mountain province, between the Campestrian on the east and the Nevadian on the west.

Now, comparing this forest-map with a geological map of the territory embraced, it will be found that the provinces and regions of the former coincide with the geological formations to a remarkable degree.

Beginning with the Lacustrine province it will be found that the formation is mostly granite, or what is popularly known as such, with some beds of Silurian and Devonian; also a few patches of tertiary rocks along the coast. Hence, the three regions comprising this province are really but one; and, accordingly, it has no trees not found south of it in the Alleghany Mountains, which are an extension of the granitic rocks. This province is characterized by its great numbers