THE ARCH^AN ROCKS. gH 



joint-detached, masses of the quartzite are surrounded and filled between by the hori- 

 zontal sandstone, the whole capped with a heavy layer of a conglomerate compbsed of 

 angular, subangular, and rounded masses of quartzite, embedded in a coarse, friable, 

 sandy matrix, which is occasionally cemented by tlie brown oxide of iron, and is not 

 unfrequently almost altogether excluded by the included boulders. The quartzite of the 

 boulders and pebbles is the same as that of the ledges further up the bluflf. Places also 

 occur, as shown in the figure, where the sand and quartzite pebbles are wedged down 

 into the joint-cracks of the quartzite. 



Eastward from the mouth of the Devil's Lake valley, in Sec. 29, T. 11 , R. 7 E, the 

 southern face of the quartzite range continues high and bold on the right hand, as far 

 as Sec. 25, T. 12, R. 8 E., in Columbia county. On Mr. Fitsimmons' place, on Sec. 22, 

 T. 11, R. 7 E., Sauk county, near Parphrey's glen, and only a short distance from the 

 south slope of the ridge, one of the highest points on the whole range of bluffs occm-s, 

 the elevation being nearly 100 feet greater than that of the Devil's Lake blufts. The 

 point is in use by the United States Coast Survey, as a signal station. North from the 

 signal station, the quartzite range has a width on top of nearly tliree rmles. As far as 

 Sec. 3, T. 11, R. 8 E., Columbia county, the south face of the range, except at the 

 higher levels, where large surfaces of bare quartzite occur, is composed of sandstone, 

 with some coarse conglomerate, which flanks the quartzite in horizontal layers. These 

 flanking sandstones are well exposed at the mouth of the Devil's Lake gorge; in Par- 

 phrey's glen, on the hne between sections 23 and 22, T. 11, R. 7 E., Sauk county; and 

 again in Dorward's or St. Mary's glen, on the line of sections 18 and 7, T. 11, R. 8 E., 

 Columbia county. In all these places, the sandstone layers appear to possess a small 

 dip, about 5°, away from the quartzite core. At Dorward's Glen, the quartzite is to be 

 seen at the north end of the gorge, and lying upon and against it sisty feet of horiz- 

 ontal sandstone and bowlder-conglomerate, as shown in Fig. 27. These are ex- 

 posed on the wall of the gorge, the conglomerate forming the base of the cKfF and 

 the stream bed, with a thickness seen of four feet. The bowlders of the conglomerate 

 are largely irregular, angular masses reaching up to eight inches in size, and ajre 

 almost entirely without surrounding matrix. The quartzite at the head of the glen is 

 non-granular, pinMsh-gray to red, and without plain bedding. 



Fig. 27. 



puarizife J^o'ijdam Sandstone and Conglomerate 



Sandstone and Conhlombbate on Quaktzite at Dokwabd's Glen. 

 Scale 90 feet to the inch. 



East of Sec. 8, T. 11, R. 8 E., as far as the end of the range, the flanking sandstone 

 appears to be wanting, outcrops of quartzite in places extending from summit to base of 

 the southern face of the range. Such a place occurs on the northern side of Sec. 3, and 

 southern side of Sep. 34, T. 12, R. 8 E., near Mr. Fleming's house. Here t'no quartzite 

 bluflf rises immediately from the north side of the Portage road, showing for the first 

 steep ascent of 250 feet, large loose masses and rough exposures of a metamorphio 

 conglomerate, in which matrix'and pebbles are both of quartzite, the pebbles bemg very 

 -small and in no wav different from the matrix. From the top of tliis slope a gradually 

 rising wooded step is crossed for about a tliixd of a mile to a second nearly precipitous 



