508 
Buell—Bo wider Train s . 
miles distant from the most remote source of its quartzite con¬ 
stituent. The overlapping of the proximal half of its area by 
the later trains prevents any approximation of the amount of 
material which should be included in this bowlder fan, but over 
the central belt of the train in the west half of Rock county, 
over a hundred quartzite bowlders and several hundred smaller 
fragments were noted, an amount largely in excess of that noted 
upon corresponding areas of the earlier fan. Its margins are 
clearly defined for only a short distance on the west side of the 
Sugar river valley. In the adjacent valley of the Pecatonica 
they are buried beneath the deep loess accumulations which sur¬ 
round the southwest margin of the succeeding drift sheet, and 
on the east side of Rock river the thick overlying deposit of 
later drift largely conceals the material of earlier deposits, only 
an occasional quartzite fragment appearing in the deeper 
rosion sections to attest the southward movement from the 
edge areas on this side of the valley. 
The breadth of the fan as indicated by the limital distribu¬ 
tion of its quartzite fragments is considerable, even when com¬ 
pared with the extreme elongation of its train. It covers al¬ 
most the whole breadth of Rock county on its north line and 
nearer the south line of the state covers the east range of town¬ 
ships in Green county and the succeeding four ranges of town¬ 
ships in Rock county. In Illinois it covers the whole breadth 
of Winnebago county and the adjacent range of townships in 
Stephenson. Its area outside of the Kettle moraine is over 
1,000 square miles. Its sharply defined west margin, in the 
east half of Green county, Wis., is its most characteristic feat¬ 
ure, marking as it does a division in the hitherto considered 
simple genesis of the older drift of the region. 
The third bowlder fan extends southwestward from the ledge 
areas in a direction about midway between the last two. I 
has a well marked proximal area, in the region adjacent to the 
two most important ledge groups; quartzites aggregating several 
hundred cords being noted on the ridge areas crossed by the lines 
of its glacial movement. Its peripheral distribution is also sharply 
defined, being confined to a narrow belt of marginal deposits 
which lie just beyond the southwest border of the Green Bay 
