DISTRIBUTION OF NORTH AMERICAN FORESTS. 519 



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 ; com- 

 mencing 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, com- 

 mencing 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 moun- 

 tains 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 La- 

 custrine 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 prov- 

 ince, 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 



