482 GEOLOGY OF CENTRAL WISCONSIN. 



On the line of the Wisconsin Valley Railroad, between Junction City and 



Knowlton, there are numerous small rock cuttings, chiefly in more or less decomposed 

 gneissic and scliistose rocks. The drift along the line is very light, and every little cut- 

 ting exposes the rock. Half a mile north of Junction City, in the north part of Sec. 2, T. 

 24, R. 6 E., small exposures are seen for a distance of 300 feet, of much decomposed, fine- 

 grained, dark-colored mica-schist or micaceous gneiss. A similar rock shows a quarter 

 of a mile further north, on Sec. 35, T. 25, R. 6 E. Here the rock is a fine-grained, very 

 closely laminated, blackish schist (963). The predominating black mineral is partly horn- 

 blende, partly mica. In the north part of Sec. 35, \% miles from Junction City, a cut- 

 ting shows for 50 feet at its south end a blackish schist, similar to the last described, in 

 all stages of decomposition, even to a light colored clay. The lamination lines are 

 marked, and bear N. 50 E. At the north end of the cut a decomposing, fine grained, 

 arenaceous, light-colored schist (962) is exposed, composed apparently chiefly of fine 

 granular quartz. On some of the laminse light-colored, altered mica is perceptible. 

 One-fourth mile further north is a small, indefinite exposure of the same arenaceous 

 schist. In the east part of Sec. 26, 2% miles from Junction City, the railroad cutting 

 makes an exposure 200 feet long and 8 feet high. The rock (959, 960, 961) is a fine- 

 grained, dark-greenish to black, calcareous mica-schist, or gneiss, showing very fine and 

 uncontorted lamination, and a peculiar knotty appearance in places from the occurrence 

 of lumps of quartz and calcite between the laminae, which are then bent around these 

 nodules. The preponderating black mineral is in fine shining scales, and appears to be 

 chiefly mica. Veins, j^ to % inch in width, of a greenish, translucent mineral (epidote?) 

 occur. The lamination of the rock causes it to break out in columnar forms, some of 

 the columns reaching a size of 8x4x4 feet. The apparent dip is N. N. W. 85. A 

 somewhat similar calcareous gneiss occurs on Black river in Clark county. Three miles 

 from Junction City, on Sec. 24, T. 25, R. 6 E., is a small exposure of a fine-grained, 

 white-weathering, crumbling, arenaceous, talco-mica-schist (858), showing very fine 

 lamination, and closely allied to the light-colored rock seen in the cutting \% miles 

 north of Junction City. "With a lens, fine-grained quartz is seen to be the predominat- 

 ing constituent. Half a mile farther north is an indefinite exposure of a fine-grained, 

 dark-colored gneiss, or mica-schist, similar to that seen in the large cutting on Sec. 26. 

 About 4 miles from Junction City, on Sec. 13, T. 25, R. 6 E., light-colored, fine-grained, 

 arenaceous mica-schist (999) is again exposed, for 300 feet, on the side of a cutting. 

 The lamination planes strike N. 30 E., and dip 80 S. E. A few small masses of milky 

 quartz, and reddish felspathic veins are included, and, in places, stand out in relief from 

 the surrounding decomposed rock. On the north part of Sec. 13, 4% miles south of 

 Knowlton bridge, an indistinct exposure of pinkish, weathered granite occurs. Another 

 indefinite exposure of the same rock occurs a quarter of a mile further north, on Sec. 12. 

 In the north part of Sec. 12, 3.7 miles south from Knowlton bridge, the following section 

 occurs in a low cutting, the rock exposures not rising more than one or two feet above 

 the railroad track, and being considerably out of position. The section begins at the 

 north end of the exposure: 



1. Granite (992): very fine-grained, red colored, felspathic; partly kaolinized 



on surface; penetrated by veins of white quartz 2 



2. Decomposed gneiss: clayey; containing occasionally seams of partly kao- 



linized reddish granite (993) 50 



3. Quartz: white 1 



4. Granite (994): partly decomposed; very fine-grained; granular, pink col- 



ored, quartzose; crumbles in fingers to a sand 3 



5. Decomposed gneiss: clayey, but showing still a distinct contorted lamin- 



ation 6 



