GENERAL GEOLOGY OF THE DISTRICT. 45o 



The parallel distribution of the detached outcrops of the Cherty lime- 

 stone and the continuous belt of Quartz-slate is evidence that the orographic 

 movement between the two in tlie Penokee district was not of a compli- 

 cated character. Also tending in the same direction is the similarity of. 

 the dip of the limestone and the Penokee series ])roper. While in some 

 places the limestone appears to have a flatter dip than the Penokee series, 

 this is not s.o marked as to suggest an uncontnrniitA- between the two were 

 it not that other data point in this direction. Taking idl the facts into 

 account, it is concluded that there was a considerable time interval between 

 the Cherty limestone and the Penokee series j^roper. In this interval 

 the limestone was consolidated, and if the chert is a seffreo-ation formed 

 from scattered organic remnins, or was introduced from outside, tliis also 

 occurred. The Cherty limestone and Basement Complex were raised above 

 the sea and erosion began. The amount of material removed it is impossi- 

 ble to estimate. It is only known that the Chert>' limestone in some places 

 is 300 feet thick, in others is absent. The presence of occasional j)ebbles 

 of jasper in the conglomerates of the Quartz-slate suggests that upon the 

 limestone was once a higher formation of a different character Avhich was 

 subsequently wholly carrieil a\\a\'. After this time of erosion the land 

 was again depressed below the sea and the lower part of the Penokee 

 series proper beg"an to be deposited. The lack of marked discordance in 

 the bedding of the Cherty limestone and the Quartz-slate is no evidence 

 that the time gap between the two was not long- enough to have produced 

 a most pronounced discordance, for this Penokee area may have been a 

 jjai't of a plain removed from zones of important folding and thrusting- which 

 may have occurred simultaneously in other districts. 



The Iron-hearing and Upper slate menihers. — Thus far the relations of the 

 Southern Complex to the two lower members of the Penokee series and the 

 relations of the latter to each other have been spoken of. Above the 

 quartz-slate follows in perfect conformity the Iron-bearing formation. This 

 member, like the major part of the Chertv limestone, has been shown to l)e 

 of a nonfragmental character. The change from the fragmental Quartz- 

 slate to the Iron-bearing member is alwaAS abrujjt. The uppermost rriem- 

 ber of the former has been said to be a coarsely crystalline quartzite. It is 



