666 GEOLOGY AND TOPOGRAPHY OF THE LEAD REGION. 



atonica river, crossing the state line .ittlie southwest corner of the 

 town of Cadiz. From here it proceeds almost in a straight line to the 

 city of Monroe. Thence north, it runs along the divide between the 

 Pecatonica and Sugar rivers, until about two miles south of New 

 Glarus, where it takes a northeasterly course, and passes out of the 

 county about a mile west of Belleville. The course thus indicated is 

 its present line as shown by erratic bowlders lying upon the surface. 

 If the drift deposits originally extended farther westward, no trace 

 thereof now remains. East of the line described, bowlders are found 

 in all parts of the county, with more or less frequency. The boun- 

 dary line, where bowlders are now found, does not appear to conform 

 at all to the surface features, but crosses the valleys of the streams, 

 and the ridges between them, with equal impartiality. 



The different kinds of rock found in the drift are so numerous that 

 it would require quite a catalogue to enumerate them all. It will be 

 sufficient to state that the great bulk of them are granitic, metamor- 

 phic, or trappean; the most frequent being varieties of granite and 

 gneiss, and next to them the trappean rocks ; chloritic rocks, and those 

 of a schistoze structure, are also quite numerous. 



In addition to tliese there are, in certain places, beds of gravel, sand 

 and clay. The distribution of the bowlders does not appear to be 

 very regular in Green county, in fact, the whole of the county verges 

 so near the western boundary of the drift, that comparatively small 

 deposits were made here, which are quite insufficient to exemplify any 

 general laws of distribution. No difference could be seen in their 

 frequency, between the eastern line of the county and the western line 

 of the drift. 



The bowlders are of various sizes, from a few inches to two or three 

 feet in diameter, and are always rounded and worn smooth. They are 

 frequently found quite numerous in one place, and then scattered 

 along at very distant intervals, on the same kind of ground, but do 

 not exhibit any distinctive morainic appearance. 



Gravel beds are not very frequent, although they are found in sev- 

 eral places in Green county. There is one situated very near the 

 boundary of the drift, on the N. W. qr. of Sec. 4, T. 1, E. 7 E., where 

 there is a bed of gravel about eight feet thick, underlaid by a'bed of 

 stratified sand and clay about four feet in thickness. This sand is 

 very fine, and has just enough clay mixed with it to make a good ar- 

 ticle of moulding sand for iron foundries; it would give a finelmpres- 

 sion, and make a smooth casting. A similar bed was found about 

 two miles east of the preceding, in the S. W. qr. of Sec. 2 T. 1 E 

 7 E., where the drift sand and gravel have accumulated to a thickness 



