92 BULLETIN OF THE 



found separate from each other, in some cases appearing to have been 

 worn by wave action before they were fixed in the strata, is almost con- 

 clusive proof that the deposits were made in shallow water. Although 

 the Exogyras differ in a certain measure from our ordinary oysters, their 

 distribution in this and other countries is always consistent with the 

 hypothesis that, like their living kindred, they did not inhabit the 

 deeper parts of the sea, but were dwellers in the shoal water. 



The existing condition of the Cretaceous fragments affords us some 

 light as to the condition of the rock before it was disrupted by glacial 

 action. All the fragments containing fossils are extremely ferruginous, 

 the lime of the shells having been replaced by limonite. This is the 

 ordinary [result of atmospheric action on superficial deposits of this 

 nature. It appears to me quite evident that this replacement of the 

 lime was effected while the material was in its original position, and this 

 for the following reasons. The fragments of Cretaceous rock were in 

 many instances found lying upon the surface of the soil, or only partly 

 bedded within it. In these cases the limonation cotild not have oc- 

 curred since the fragments came to their present position, for the 

 reason that there would have been no source whence the iron could have 

 been derived. There has evidently been no considerable degradation of 

 the drift on this region since it was abandoned by the glacier. Owing to 

 the position of the deposit it was not subjected to any water erosion. It 

 is evident that the corrosive work since the disappearance of the glaciers 

 has not taken away more than a few inches, if as much, from the surface. 

 If the fragments had come to their present position without having ex- 

 perienced the processes of decay, the replacement of the lime could not 

 have been effected. I therefore am forced to the conclusion, that this 

 material had decayed in its original bed, before it was disrupted by the 

 glacier, and that the iron was derived from superjacent beds in the origi- 

 nal stratification. Although this conclusion is hypothical, it is of certain 

 interest, for the reason that it combines with the other known facts to 

 indicate that the glacial erosion which has taken place in this region 

 has been of slight amount. If it had been great in quantity, if several 

 hundred feet of the section had gone away, we should not only have had 

 this detrital material of Cretaceous age distributed over a larger field, 

 but the fragments would probably have come to this point in an unoxi- 

 dized condition. 



A very severe rain-storm which occurred in the month of September, 

 1888, disclosed a portion of the sections in the neighborhood of the point 

 where Cretaceous fossils are found. Although the sections are obscurely 



