690 F. W. SARDESON 
disruption, and to be laid down without dissolution. The pecul- 
iar rolling up of sand strata into lenticular masses between clay 
strata might not be easily produced by any single continued 
thrust of an overlying glacier, but might easily be the result of 
successive reverse sliding movements. 
Very little, if any, attention has been paid to this Clay Bank 
by geologists since N. H. Winchell briefly described it, but it is 
not without scientific interest in its present significance, whether 
it is Cretaceous or Pleistocene. It has also a high commercial 
value. Professor Winchell believed that this clay and sand 
deposit might extend over several square miles and he has repre- 
sented about sixteen sections on the map of Goodhue county 
(op. cit.). He has described a number of observed and reported 
Cretaceous exposures as occurring from two to fifteen miles dis- 
tant, but none of these afford the desired evidence. Clays like 
that at Clay Bank might of course be expected to occur in other 
places in the drift and only the occurrence of strata unquestion- 
ably 2 s¢éu can prove the same to have been deposited as Creta- 
ceous, not as Pleistocene, in this region. There are also two 
other deposits which may be mistaken in this region for Creta- 
ceous. One, the ferruginous conglomerates of the oldest drift, 
a sort of residuum of the oldest till, occurs here and there. No 
ferruginous conglomerate nor any gravels were observed in the 
‘strata of the Clay Bank, and indeed none are known to be from 
Cretaceous strata. A more deceptive deposit in this particular 
region is the variegated clays of the Shakopee formation. Such 
an exposure is seen one mile north of Clay Bank station in a 
railway cutting, where three or four feet of clay strata cover 
the side of a dolomite swell. When weathered, this clay remains 
long intact, while the dolomite strata above and beneath it are 
reduced. It might then be mistaken for a Cretaceous clay. 
There are no Cretaceous deposits known in southeastern Min- 
nesota which are unquestionably zm seéu, although Cretaceous 
clays, with fish teeth and bones or fossil leaves in sandstone, are 
not infrequently discovered in any of the ‘‘northwestern drift” 
in Minnesota. Their occurrence does not prove the proximity 
