426 DESCRIPTION OF THE COUNTRY BORDERING 



Since these four systems of rocky beds and masses underwent their last distur- 

 bance, the superficial materials have been deposited, reaching from the lake-level, 

 and from unknown depths below, up to the highest summits, 1282 feet above the 

 Lake, or 1906 above the Ocean. I do not feel at liberty, on account of the total 

 absence of fossil shells, to place these materials in any recognised division of the 

 Tertiary. They are doubtless of the Quaternary epoch, and are connected in their 

 origin with sudden and recent movements and upheavals on the north shore, 

 attended by intense heat, by which causes the ancient waters were powerfully 

 agitated and charged with mud and coarse gravel. 



These deposits admit of but two subdivisions : 



<t. Red clay. 



I>. Boulder drift, coarse sand, and gravel. 



This distinction is based, however, more upon the different materials that compose 

 the beds, than upon a difference of age ; for it is most probable they are cotempo- 

 raneous. 



a. Red Marly Clay. — This is a fine-grained, homogeneous marly sand, cemented 

 by argil or clay, with well-defined horizontal lines of lamination or deposition ; 

 containing, but very rarely, pebbles of granitoid, trappose, sandstone, conglomerate, 

 or slate rocks. This constitutes the shore or lake bluffs most part of the way from 

 the Montreal to the Brule ; the red sandstone, on which it rests, showing itself occa- 

 sionally beneath. It is easily washed away in suspension by the waves, and having 

 little tenacity, falls in slides and avalanches into the water, and is thus cut into deep, 

 narrow gullies by rains. Its surface, in the District explored by me, is no more than 

 two hundred and fifty feet above the Lake, sloping gradually from the mountains to 

 the shore, as though it formed at one time the bed of an ancient sea. Beyond my 

 District, however, on the waters of the St. Louis River on the west, and of the 

 Ontonagon on the east, the red clay deposits reach to the height of four hundred 

 and fifty to five hundred feet above the Lake. 



Although it is called a clay, there is very little of it sufficiently argillaceous to 

 make brick. On Madeline Island, and on the Maringouin Fork of Bad River, there 

 are patches from which brick can be made, but in general it is too sandy, or too 

 calcareous. 



Specimen No. 46,* collected by me from the Maringouin Fork of Bad River, two 



* Water of absorption, ...... 5-5 



Matter insoluble in hydrochloric acid, 59-0 ; of this, after fusion with 



carbonate of soda, 13-4 was soluble, leaving insoluble 

 Pure silica, ........ 46-6 



Carbonic acid, ....... 7 - 0 



Sulphuric acid and chlorine, ...... a trace. 



Soda, ......... 2-6 



Potash, ......... 0-6 



Alumina, soluble in hydrochloric acid before fusion with carbonate of soda, 7-0 

 " " « after « « << 10-5 



17-5 



