500 
Buell—Bowlder Trains. 
area of this train, though small as compared with that noted in 
either of the bowlder fans previously described, is ample for the 
purpose of identification and definition, and through the median 
portion of the belt forms a considerable percentage of the 
crystalline drift found on the surface. About a hundred bowl¬ 
ders and bowlderets have thus far been noted in the region and 
several hundred smaller fragments. Evidences of glacial wear 
and reduction are not markedly manifest, as may be shown by 
the number and comparative size of the bowlders found in the 
train. There is, however, abundant evidence in the weather¬ 
worn and somewhat pitted surface of most of the material that 
it represents an epoch of glaciation very much older than that 
of either of the preceding trains. This is seen most strikingly in 
the larger fragments. Many of the smaller fragments indicate 
by their surfaces of fresh fracture that they have been much 
broken up in the process of post-glacial weathering. 
THE WESTWARD TRAINS. PLATE XVI. 
Area of distribution .—This exceedingly interesting evidence 
of the complexity of glacial operations that have taken place 
within the area was the last to be identified in the study of the 
drift phenomena of the region. Some of the material found in 
the vicinity of the ledges was, however, noted in my earliest ex¬ 
aminations of the region, soon after the discovery of the most 
remote source of the quartzite drift in the ledges of the Mud 
Lake area. It was then thought, however, to have originated 
in some local ledge surface at present concealed beneath the 
general drift, and the few scattering fragments found at re¬ 
mote localities, in the absence of definite proof, were referred 
to distant Archaean sources. But the proofs of identity afforded 
by microscopic examination together with the more careful 
working out of the limits of this area of quartzite distribution 
determined the relations of the material as completely as in any 
of the other areas. 
The area of its distribution lies entirely within the Green Bay 
lobe, but is more completely separate from its fellows than any 
of the others. The train from the Lake Mills ledge alone inter- 
