Descriptions of the Exposures. 
261 
ledge several low domes and flat planed surfaces of quartzite 
define the southern limit of the area. The length of the Port¬ 
land area is two miles and its greatest breadth three-fourths of 
a mile. 
The Hubbellton area is second in size and importance to the 
last. It lies parallel with this and they are separated by a 
ridge and marsh covered interval a mile and a half wide. Its 
northern exposure is a bare knob of rock projecting from the 
end of a drift ridge near the center of the northwest quarter of 
Section 36, Portland township. In a ravine on the west slope 
of this ridge the quartzite is again exposed for several rods. A 
quarter mile south on the center line of Section 36, is a low drift 
ridge from whose surface the quartzite protrudes at several 
points. On the western border of this ridge a bare ledge rises 
from the marsh level and extends for several hundred feet along 
the.general trend of the area. 
The remaining exposures are in Section 2, Waterloo township, 
being separated from the last by a half mile of marsh interval. 
The principal ledge outcrops form the north end of a drift 
ridge and extends in the direction of its strike for 300 feet 
along the east margin of its slope. The crest of the ledge rises 
about twenty feet above the marsh level and the breadth of the 
exposed surface is seventy feet. A second outcrop was lately 
discovered in a low, wooded swell an eighth of a mile southeast 
of the ledge just described. This consists of rounded edges of 
rock strata that just appear above the surface over an area of 
about an acre. In the marsh a quarter of a mile farther south¬ 
east is another tree-covered ridge with its crest almost com¬ 
pletely Covered with quartzite blocks, indicating the presence 
of a ledge at no great depth beneath. These exposures outline 
an area a mile and a half long and a half mile wide. 
The single outcrop in the Lake Mills area was found by Pres¬ 
ident Chamberlin* in tracing to its origin a well-marked bowl¬ 
der train that crosses the east half of Lake Mills township. 
The ledge has, therefore, received that name, although it lies 
on the east ledge of Waterloo township on Sections 24 and 25. 
It is four miles south of the Hubbellton area on the east mar- 
* Geology of Wisconsin, Vol. II., p. 253. 
