474 



GEOLOGY OF CENTRAL WISCONSIN. 



13. Gneiss: first 4 feet is coarse-grained, pinkish, and qnartzose (851), resem- 

 bling that at beginning of section. This grades into a light-gray, coarser 

 kind, which has a very .jagged fracture, is less micaceous, shows whitish 

 felspar predominating overphik, and only obscure lamination, and is much 

 cross-jointed (853). At 100 feet the bedding becomes distinct, the strike be- 

 ing N. 85° E., the dip 52° S. E. At 230 feet the strike is N. 85° E., the dip 

 50° S. E., the rock (854) being coarsely mottled gneiss with much greenish 

 mica and large-faced reddish felspar. At 280 feet the bedding is the same, 

 and a small red felspar vein occurs. At 300 feet the strike is N. 70° E'., the 

 dip 55° S. E. A iine-grained, red granite vein occurs here having the form 

 indicated in Fig. 9. 



Pig. 9. 



Feot. 



Grastitb Vein at Grand Rapids. 



At 340 feet the bedding and lamination of the rook become obscure again 

 and continue so for a hundred feet. At 360 feet numerous thin veins of 

 quartz occur, and at 380 feet one of pure white quartz 4 feet wide. At 420 

 feet are some large veins of red granite. One of these is figured in Fig. 9. 

 At 440 feet the bedding becomes plain again, the strike being N. 85° E. and 

 dip as before. The rook here (856) is much less micaceous and more fels- 



pathic than for some distance back, and is much weathered 494 



U. Covered 190 



25." Granite: pinkish, jointed, without indications of bedding 40 



16. Gneiss: dark-colored; at 40 feet this changes to a rock (858) which closely 

 resembles that at the close of 3 (856), and is moderately coarse, not very dis- 

 tinctly gneissoid, with much hyaline quartz and large-faceted felspar. At 

 60 feet a gi'anite vein 50 feet long occurs in this rock, coinciding with the 

 bedding, and striking N. 75° E., with a dip 50° S. E. The vein matter 

 (859) is a rather fine-gTained, pinlrish-red granite, weathering dirty brick- 

 red, and showing in places a partial kaoUnization. Fine grained translucent 

 quartz and pinkish felspar make up most of this granite. Mica is present, 



but in very small quantity 130 



n. Coeered 30 



18. Gneiss: gi'ay, with much black mica, sunUar to that of 16 (858). At 10 feet 

 a granite vein 2 feet wide occurs, coLiciding' with the bedding, which here 

 shows a strike of N. 73° E., and a dip 55° S. E. Other smaller granite veins 

 occur. Junction with the next rock concealed 100 



