CHAPTER II. 



RON, DISTURBAWCl AND m:\TPATl >X Of strata — GENERAL PHT81 At 

 U Of l'lli: HOBTHWEST. 



The geological series in our State is very complete l*:r,in t lie 

 •i of the oldest known rocks, to the top of the Carb >nifer- 



ous System. From tliis point to the Glacial Drift, the formations 

 observed in other parts of the county arc, as Par as investiga- 

 tions have extended, entiroly wanting*. All thai portion of the 

 Michigan series lying ab >ve the Niagara Gk >up, ; s found within 

 the limits of the Lower Peninsula; while the Niagara Group 

 and all rocks below, are confined to the CJpper Peninsula and 

 the islands at the head of Lake Ilur m 



The rocks of the Upper Penmnda not having- as yet come 

 under the observation of the present survey, it is not deemed 

 necessary to refer to them at the present time, any further than 

 to show their connection with the geology of the contiguous 

 districts. 



In order to convey a clear idea of the superposition and lines 

 of outcrop of our different rocks, it will be desirable to offer a 

 few words on the general conformation of the strata of the 

 Northwest Although the stratified rocks of the country suc- 

 ceed each other in regular ascending order, it must not bo sup- 

 posed that these strata always occupy a horizontal position, 

 that they are necessarily continuous between distant points, or 

 that :. ; is always actually overlain by 



i which belong'higher in the scries. The sediments fr< m 

 ! formed, were 'seldom deposited in per* 



fectlj &1 B m 1' >t1 en-, but U) facilitate our explanation, 



. a they were. We will sup; ., that 



monts was deposited upon another for the 



space of man;- .:.d forming a thickness of several thou- 



