146 Wisconsin Academy of Sciences^ Arts, and Letters. 



each side of the river valley, from one to ten miles apart, and 

 from 100 to 400 feet high, composed mainly of horizontally 

 stratified rocks ; and in the case of the Wisconsin, of Magne- 

 sian Limestone of the Silurian formation. The slopes, how- 

 ever, are often covered with earth and green grass. The sand 

 feature is a level or nearly level terrace mainly composed of 

 sand, though occasionally having a rich surface soil. This ter- 

 race is from 20 to 60 feet above the level of ihe water. It is 

 never continuous throughout the valley on either side, and 

 rarely of much extent but on one side at a time. It is proba- 

 bly the shallow part of an ancient water-course which once 

 occupied the valley from bluff to bluff. It is now generally 

 above overflow. The third feature is the bottom land of the 

 river, generally overflowed at highest stages, and having the 

 high bluff or terrace for its margin. This bottom contains 

 many lakes and marshes, and is cut up by sloughs forming 

 islands. These islands sometimes divide the main stream into 

 nearly equal parts. The margins of these bottom lands are, 

 in the natural state, generally wooded, and form the banks of 

 the streams at moderate stages when the sand bars are covered. 

 The fourth feature is the bed of the stream, which includes the 

 part covered at medium stages, but large portions of which be- 

 come dry sand or gravel bars at very low ones. There are 

 thus four different prominent branches or levels in the river 

 valley: 1. The level forming the main bluff. 2. The sand 

 terrace generally above overflow. 8. The bottom land gener- 

 ally overflowed at highest water. 4. The bed of the stream. 

 In 1867, a careful survey under direction of Gen. Warren was 

 made of the Wisconsin river from Kilbourn City to its junc- 

 tion with the Mississippi river. A continuous transit line was 

 carefully measured and staked off on one bank or the other of 

 the main river, as was found most easy and all the topography 

 sketched along it. The opposite shore was located by triangu- 

 lation across. A careful line of levels was run, noting fre- 

 quently the height of the bottom lands, or sand terrace when 



