LOWER MAGNESIAN LIMESTONE. 281 



rable thickness. On the south face an exposure exhibits the same section, with some- 

 thing' of the usual tendency to variableness. 



On the north hill, near the crest, a quarry has been opened in straw colored, calciferous 

 strata, whose bedding, as exposed, ranges from 2 inches to 12 inches in thickness. Cer- 

 tain layers are somewhat greenish, and green spots abound in others. The slope below 

 affords occasional glimpses of gray and green sandstones. 



It may be stated incidentally, as an interesting fact, that a loose block of Trenton lime- 

 stone was found on the summit of this hill. 



The character of the inagnesian limestone reposing on the summits of these hills dif- 

 fers somewhat, it will be observed, from that of the lower beds of the Lower Magnesian 

 limestone on the opposite side of the Wolf river, and may not belong to precisely the 

 same horizon, but it is evident that it cannot belong to a higher, and if it does not be- 

 long to the same geological level, must constitute an intercalated band in the Potsdam 

 sandstone. But the elevation of the junction of the sandstone and limestone on Mus- 

 quito Hill was estimated to be 100 feet higher than the junction of the sandstone and 

 limestone on the opposite side of the valley. It appears then that for a distance of about 

 twenty miles (how much more is not known), the formations on the north side of the 

 valley are notably higher than on the south side. While it is possible that all this 

 may be due to a southward dip of no great magnitude in itself, but quite unusual in 

 these formations in this region, especially in that direction, it seems more consonant 

 with all the facts of the case, to suppose that tho valley represents the line of a fault 

 with a downthrow on the south side. 



It is in this region that the stair-like border of this and the higher formations is most 

 conspicuous. From the eastward-bearing ledge just under discussion, the western limit 

 oi the formation runs in its irregular zigzag way, almost due north to Lake Shawano, 

 where it turns again nearly due east along the south side of the Oconto river. 



Passing by for want of space several ledges that occur in the towns of Black Creek, 

 Cicero, Lesser and Hartland, which will have value as the country develops, we find at 

 the angle made south of Lake Shawano, the following beds forming the summit of a 

 bluff 133 feet high, the lower portion of which is Potsdam sandstone. (Sec. 34, S. E. qr., 

 T. 27, R. 16 E.) 



1. Earth. 



2. Rather thin bedded, shaly arenaceous magnesian limestone, 4 feet. 



3. Bluish irregular magnesian limestone, containing geodes of quartz, 3 feet. 



4. Compact silicious limestone, 1 foot. 



5. Grayish white magnesian limestone, 8 niches. 



6. Cherty magnesian limestone, 1 foot and 6 inches. 



7. Light gray magnesian limestone, 3 feet. 



8. Oolitic layer, 2 feet. 



9. Concealed, 3 feet. 



10. Oolitic layers, 3 feet. 



11. Light colored magnesian limestone, partially exposed. 



12. Slope, concealing sandstone. 



At Oconto Falls the following section is shown: 



1. The uppermost portion exposed consists of grayish buff, silicious dolomite, of me- 

 dium hardness, somewhat uneven texture, being in part minutely granular crystalline, 

 and in part earthy, containing frequent cavities varying from the size of a pea to that of 

 a walnut. These cavities are sometimes partially lined with quartz crystals, but these 

 miniature geodes are so much less prevalent than in the layer below, which is studded 

 with them, and with clusters of quartz crystals, as to make this a distinguishing feature. 

 The bedding is irregular, but as exposed in the face of the gorge, the layers are from one 



