482 GEOLOGY OF CENTRAL WISCONSIN. 



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



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

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

 ting exposes the rock. Half a mile nwih of Junction City, in the north paj:t of Sec. 2, T. 

 24 R 6 E., small exposm-es are seenfor a distance of 800 feet, of much decomposed, fine- 

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

 of a mile further north, on Sec. 35, T. 2o, R. 6 E. Here the rock is a fine-grained, very 

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

 blende, partly mica. In the north part of Sec. 35, 1% miles from Jmiction City, a cut- 

 ting shows for 50 feet at its south end a blacldsh schist, similar- to the last described, m 

 aU stages of decomposition, even to a hght colored clay. The lammation Unes are 

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

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

 granular quartz. On some of the lammse hght-colored, altered mica is perceptible. 

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

 schist, in the east part of Sec. 26, 2}4 miles from Junction City, the railroad cutting 

 makes an exposure 200 feet long and 8 feet high. The rook (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, M to % inch in width, of a greenish, translucent mineral (epidote?) 

 occm-. The lammation of the rock causes it to break out in columnar foi-ms, some of 

 the columns reaching a size of 8 x 4 x 4 feet. The apparent dip is N. N. W. 85°. A 

 somewhat similar oalc^eous 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, crumbhng, arenaceous, talco-mioa-scMst (858), showing very fine 

 lammation, and closely allied to the light-colored rock seen in the cutting l}i i™les 

 north of Junction City. With a lens, flne-gramed quartz is seen to be the predominat- 

 ing constituent. Half a mile further 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 milos from Junction City, on Sec. 13, T. 25, R. 6 E., light-colored, fino-grained, 

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

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

 quartz, and reddish felspathio veins are included, and, m places, stand out m relief from 

 the surrounding decomposed rock. On the north part of Sec. 18, 4}4 mUes south of 

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

 indefinite exposure of the same rock occurs a quarter of a mUe furtlier 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: 



M. In. 



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- 



hnized reddish granite (993) , 50 . . 



3. Quartz ; white 1 . . 



i. Granite Wi): partly decomposed; very flne-gramed; granular, pmk col- 

 ored, quartzose; crumbles in fingers to a sand 3 . . 



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

 ation fi . 



