AND 11 1 D a E S. 



337 



between them, than those in the hornblendic and trap region. They are also more 

 rounded ; and the scenery is destitute of that bold and picturesque character Avhich 

 the greenstone ridges impart to it. 



The elevating forces appear to have acted with equal energy on both sides of 

 Lake Superior : the elevation of the granitic water-shed, which passes into Wis- 

 consin between the sources of Montreal River and Portage Lake, and pursues a 

 southwesterly course, being nearly or quite as high above the sea-level as the 

 highest range of granite hills north of Lake Superior. The highest ridge met with 

 on the " boundary-line," where the waters divide, was only 1260 feet above the 

 lake-level; while the water-shed south of the Lake was found to be 1150 feet above 

 the same level, or nearly one hundred feet higher than Ashawiwisitagon Portage. 

 That the periods of eruption and elevation were as distinct and various as the 

 different systems of dikes, is conclusively shown by the disturbance of the different 

 strata of sandstones, shales, and grits, and the conglomerate beds met with at 

 different localities, and by the variations in the dip of the bedded rocks, in accor- 

 dance with the direction of the lines of disturbance. 



While there is great uniformity in the dip of the rocks over the whole extent of 

 country between Lake Superior and the Mississippi, the greatest confusion prevails 

 on the northwest shore of the Lake, in consequence of a want of parallelism in the 

 ridges and dikes of the various eruptive periods. The volcanic grits, which make 

 up a portion of the series of the Lower Silurian period, do not extend the whole 

 length of the coast, and this, again, is productive of confusion when the whole series 

 comes to be compared at different points. The great amount of denudation or 

 erosion on the north shore, also adds much to the complexity of its geology, espe- 

 cially with respect to the eruptive rocks. The stratified rocks, however, are well 

 defined at some localities, and afford material aid in elucidating the associations of 

 the others. 



The northern mountain range dies out in a great measure after crossing St. Louis 

 River in its course southwest, but the granitic, metamorphic, and trap rocks are 

 met with at various points along the line of bearing, in the beds of the streams, and 

 rising in low knolls through the drift, as far as the Mississippi, which they cross, as 

 before stated, between Omoshkos and Clear- Water Rivers, and reappear again, in 

 the line of bearing, on Minnesota River, between the mouths of Red Wood and 

 Little Waraju Rivers. 



In their general line of direction, few of the chains of hills north of Lake Supe- 

 rior tower to any great height above the others. On the tops of the high ridges 

 the rocks are sometimes bare, but are generally covered with mosses and lichens, 

 and a stunted growth of evergreens. The naked rock, which is sometimes several 

 acres in extent, is generally smooth, often polished, and almost always exhibits 

 numerous parallel lines of scratches and grooves. 



Before proceeding to give the details of the examinations made north of the west 

 end of Lake Superior, it may be well to refer again to the fact, that between Fond 

 du Lac and Pigeon River, the Lake shore conforms in its general direction to the 

 line of bearing of the ranges of trap which begin at the Grand Portage of St. Louis 

 River, and proceed in a northeasterly direction toward the Falls of Kamanitiquoia 



43 



