122 THE PENOKEE IliON-BEx\.RlNG SERIP^^. 



C(Hitainsniiimt<' tal)ular crystals of feldspar. In this matrix are found large, 

 miu'li altered crystals of the same mineral. Menaccanite and leucoxene are 

 also abundant in small granules. These rocks would be regarded ordinarily 

 as modified porphyrites, although in the field and in hand specimen there is 

 the strongest possible foliation. In character they are allied to some of the 

 various finely crystalline quartzose gneisses which stand intermediate be- 

 tween the two main phases described. 



The Eastent (/ranife. — In all essential respects the massive rocks here 

 contained are like those found in the granite areas to the westward. The 

 phases here included run from typical syenites to t3q)ical quartzose granites. 

 Usually in them, as in the })revious areas, an alkaline feldspar, occurring 

 largely in idiomorphic forms, is the chief constituent. In a few of the ex- 

 posures quartz is as aljundant as the feldspar. In some cases in this area 

 the decomjxtsitiou of the fehlspar has gone far. Aside from the quaitz and 

 feldspar, hornblende and chlorite, as in the Central granite, are the only 

 inqiortant miiuM-als, and very frequentlv the chlorite, as in it, has resulted 

 from the alteration of the hornblende or the decomposition of the feldspar. 

 The typical syenite exposures are more common tlian in the other two granite 

 areas. 



Included in each of the foregoing areas are here and there exposures of 

 fresh diabases. These rocks in everv i)articular are like the diabases so 

 abundantly contained as dikes in the Penokee series, and no doubt were 

 contemporaneous if not actuall}' continuous with them. The description of 

 these rocks is given in Chapter vii. 



Smnniarji. — The kinds of rock mentioned in the Southern Comple'x are 

 not necessarih' all which may there exist, foi' the traverses were not fre- 

 quent enough to find more than a fi'action of the exposures. The narrow 

 range in the lithological character of the granite is Acrv noticeable. Three 

 large areas of rock, in which the easternmost exposures are fully !)0 miles from 

 the westernmost ones, are alike in every important particular. This likeness 

 of character suggests, as does also their distribution, as seen in PI. 11, that these 

 areas are really counecte<l. It is also suggestive that a like condition of 

 affairs ])revailed for a very considerable distance at the time of the forma- 

 tion of these locks. 



