492 
Buell—Bowlder drains. 
belonging to this episode as determined from observations made 
upon drift sections found in all parts of the field is sufficient to 
indicate a degradation from the glacially exposed surfaces of 
from fifty to seventy-five feet. 
THE SOUTHWESTWARD BOWLDER TRAINS. PLATE XIV. 
Outlines of bowlder fan .—The quartzite distribution indi¬ 
cated on the accompanying map is believed by the author to 
have been brought about by a glacial episode next preceding 
that which is bounded by the Kettle moraine. 
The presence of this older train is indicated within the area 
of the Green Bay lobe by a considerable amount of quartzite 
material in the drift over areas to the southwest of the ledges 
and west of the main trains. It is also sharply determined by 
their presence in abundance in the old moraine belt beyond the 
area occupied by the Green Bay lobe. 
Its most abundant distribution is upon the area between the 
Mud Lake and Portland ledge groups, on the west side of the 
Mud Lake basin. The drumlin clusters on both sides of the 
Crawfish in the southeast quarter of Portland township show 
among the bowlder material on their surfaces a large proportion 
of the Mud Lake quartzite. These are especial]y abundant on 
the roadsides crossing sections 24 and 25, and sections 23, 26 
and 27. On ridge crests north of the Crawfish and west of the 
marsh tributary to Mud Lake from 2 to 5 cords per acre were 
noticed at several points. An estimate from a large number of 
observations made upon this area indicated about a thousand 
4 
cords of the local crystalline drift upon the surface between the 
two areas. Southwest from the Portland ledges, the quartzite 
drift is much less abundant upon the surface but is still found 
on all ridge areas, across Medina township, the southeast 
corner of Sun Prairie, and in Deerfield, Blooming Grove, Pleas¬ 
ant Springs, Dunn, Fitchburg and Butland, to the margin of 
the Green Bay lobe in Oregon and Verona. 
Its distribution beyond the Kettle moraine in Montrose and 
Oregon townships, Dane county, and Albany township, Green 
county, is its most characteristic development. The sharp outer 
