PKE-KEWEENAWAN FORMATIONS 699 



is adjacent to a north-south line from the center of section 21 

 southward about one mile to the granite near the center of section 

 28, T. 47 N., R. 43 W. The upper quartzite member underKes the 

 Ironwood formation near the center of section 21. Proceeding 

 southward there are numerous exposures and test pits showing the 

 characteristic lower horizons of interbedded quartzite, quartz slate, 

 and graywacke, complexly folded and cut by numerous quartz 

 veins. From about 800 paces south the veins of apHte and pegma- 

 tite appear and the rocks become noticeably micaceous and horn- 

 blendic, with a gradual disappearance of clastic structure until they 

 give place to those more properly described as mica-hornblende 

 schist and gneiss. This mineralogical transition is accompanied 

 by a gradual increase in the size and number of the aplitic and 

 pegmatitic veins. " The granite first occurs in intimate interbanding 

 with hornblende gneiss and finally excludes it entirely. 



In the vicinity of section 25, T. 47 N., R. 44 W., and section 30, 

 T. 47 N., R. 43 W., the Presque Isle granite has apparently eaten 

 its way upward through the upper heavy quartzite of the Palms 

 into the Ironwood formation, and has very probably displaced or 

 absorbed both of these formations in the E. |- of the former town- 

 ship. In these localities the Palms formation is apparently absent 

 and the Ironwood formation is represented by amphibole-magnetite 

 schist, which in section 25 is separated from hornblende syenite 

 by a narrow strip about 150 feet wide in which there are no 

 exposures. 



In the workings of the Presque Isle mine on section 21, T. 47 N., 

 R. 43 W., a conspicuous feature of the Ironwood formation is the 

 occurrence of an unusual abundance of anastomosing quartz masses 

 and veins. Pit dumps and drill records indicate that this feature 

 is not local but general throughout the iron formation in this town- 

 ship. This phenomenon coupled with other evidence of granitic 

 intrusion has considerable significance. 



We take care to state that complete mineralogical gradation of 

 either member of the Animikie into granite cannot be observed in 

 any single exposure, but that such gradation is a fact and accounts 

 for the absence of identifiable contacts is a conclusion which rests 

 on field observations which admit of no other interpretation. 



