18 THE PENOKEE IRO^ST-BEABING SERIES. 



1. Sedimentari/. 



a. Red sandstone. 

 h. Black slate. 

 c. Oonfiloini'iate. 



2. Trajypoux Rochu, or tlioxe of vokanic origin. 



a. Black and red amygdaloid and greenstone trap. 



b. Augitic, borubleudic, and feldspathic rocks, embracing syenite and 



giaiiitcs of the same age. 

 5. MctumorphoHid h'ockn. 



(>. Hornblendic slates. 

 h. Iron slates. 



c. Black slates, in large, thin, rectangular sheets. 

 (\. Talcose slatcs,.Avith (juartz. 



c. Slaty quartz. 

 4. Granitic. 



a. Syenite, and 



b. Granite, occupying the country south of the mountain range or uiilift, 



are the oldest rocks seen. (P. 425.) 

 The iSedimcntarfi (itid Ljneoux h'ocls. — The relative <(<ii' of the rocks beneath the 

 clay and drift is a subject iii)on which a prolonged discussion would be in place if 

 theoretical consideration might be introduced liere at large. Tiie granites and 

 syenites of the interior are no doubt the most ancient rocks of the district. After 

 the protrusion of those extensive interior granitic masses many successive changes 

 have occurred, but in what precise order is a <|uestioii not easily determined. The 

 immense sandstone deposits of the basin of lake Superior nuist have been subse- 

 quent to the granites of Wisconsin, Chippewa, and Montreal rivers, and probably 

 rested on tlieni. Since that era a prolonged and intense internal igneous action has 

 taken place, and the traj), hornblendic, and greenstone masses have been ejected, and 

 also with them irregular protrusions of recent granite and syenite. Tlie metamorphic 

 slates have been elevated during these convulsions, aiul the sedimentary rocks thrust 

 away to the northward and tilted up at high angles. 



The old granites and syenites have been rent, and fluid matter, such as cjuartz and 

 hornblende, inserted in the ftssures and between the beds. -Vlong the northern por 

 tiou of the Penokie range an otitburst has taken place, as it were, between the sedi- 

 mentary rocks and their ancient basis, on a line from the Montreal to Lac des Anglais; 

 but the overflows liave not been coutined to one \olcanic effort. The black and red 

 trap, against which the conglomerate abuts, is doubtless due to a dili'erent effort from 

 that which produced the greenstone trap-rocks that rise between the East fork of 

 Bad river and the Montreal. The augitic, liornblendic, and syenitic mountains 

 between the Kast fork and tlie main stream ditier in form, in chemical constitution, 

 and bedding or stratitication from cither the greenstone or black trap. 



