SURFACE GEOLOGY. 667 



of about twelve feet. A large amount of it lias been utilized for 

 railroad ballast. A third bed, like the other two, was observed on 

 the N. E. qr. of Sec. 2, T. 1, R. 7 E., also several others in various 

 portions of the county. Those already described will serve as sam- 

 ples of all. 



The amount of drift clay in Green county is comparatively small, 

 it probably having been dissolved out and washed away from the 

 greater portion of the surface. It was only observed in one pl.'tce, in the 

 ~N. "W. qr. of Sec. 25, T. 3, R. 7 E., where a well had been sunk in 

 the drift. There was here a thickness of about twenty feet of slate- 

 colored clay, full of small pebbles. 



Outside of Green county, the indications of drift observed were so 

 few and imcertain, that it seems scarcely proper to attribute them to 

 glacial agencies, and, on the other hand, there is great difficulty in 

 accounting for them in any other manner. They are briefly as fol- 

 lows: 



Prof. Whitney describes, on page 137 of the report of 1862, a group 

 of loose blocks of sandstone, which are situated as he represents them 

 in his wood cut. It is referred to in this connection, because I de- 

 sire to report with it two similar deposits, which have been observed. 

 The first is situated on the road from Mineral Point to Dodgeville, 

 on the S. E. qr. of Sec. 9, T. 5, R. 3 E, as much as three miles from 

 any outcrop of the St. Peters sandstone. The bowlders are from one 

 to two feet in diameter, and lie scattered along the road, and in the 

 adjacent fields, on the south slope of the hill. The bowlders are none 

 of them very large, and it is not impossible that they were hauled 

 there, although it is difficult to understand for what purpose. There 

 are not now, nor have there ever been any houses near them. 



The second locality is on the 1ST. E. qr. of Sec. 5, T. 1, R. 2 E., on 

 the ridge between the Strickland and Myers branches. There are 

 here quite a number of blocks of St. Peters sandstone lying on the 

 summit of the ridge. The blocks are of various sizes, some of them 

 weighing several tons. These bowlders are more distant from any 

 outcrop of sandstone than either of the others; the nearest being at 

 " Cook's," about five miles to the northwest, in Sec. 22, T. 2, R. 1 E. 

 It is somewhat singular that these isolated bowlders should always bo 

 of sandstone. These several instances have been cited as quite remark- 

 able and singular exceptions to the general driftless character of the 

 Lead region, although we have no very plausible theory to account for 

 their origin. 



