1875.] 397 [Dodge. 



II. Stratified Rocks. 



Between the older rock bands described lie certain more recent 

 and more clearly stratified rocks. The more recent age of these is 

 shown beyond dispute by their position in relation to the underlying 

 crystallines, as well as by the fact that they are composed of detritus 

 of the latter, which may not only be so recognized, but even may at 

 times be referred to the source from which it was probably derived. 



Their age relatively to each other is less easily determined. They 

 are, in places, fossiliferous, but elsewhere have not yet been shown to 

 be so. This scarcity of organic remains makes certainty as to age 

 impossible at present, in some instances, for the rocks are much 

 faulted, and are, beside, frequently worn away by glaciation and cov- 

 ered by gravel at critical points. So that mere succession at the sur- 

 face, in the direction of dip, is not a safe test of superposition. 



The occurrence of Paradoxides at Braintree connects the strata 

 holding this characteristic fossil, with rocks at St. John, New Bruns- 

 wick, and in Newfoundland. It is interesting to notice that the 

 strike of these earlier rocks is about the same at nearly all the places 

 where they have yet been studied; in Sweden and Great Britain, in 

 Bohemia, and in Spain, as well as at the localities just mentioned; as 

 if some identical force had given the east-north-east and west-south- 

 west direction to them before others existed above the water, the 

 force acting as a simple result of the nature of the earth in its then 

 condition. 



It is not yet safe to attempt minutely to synchronize the earliest 

 fossiliferous strata in different regions of this country. They are, of 

 course, dissimilar lithologically, and nowhere have they been so accu- 

 rately worked out as to serve as a standard of comparison for the 

 rocks of other and remote districts. With a few exceptions we do 

 not know what of our rocks correspond to the Lower Cambrian of 

 Wales and England, and there has been much confusion in America 

 in the use of the term " Huronian, " which seems to have been made 

 to include early crystallines (such as are represented in this vicinity 

 by the sienites and diorites already described), and higher and more 

 clearly stratified and fossiliferous rocks of Cambrian or Silurian age. 



Studying these rocks by their internal characteristics, we arrive 

 conclusively at the result that there are strata of several different 

 ages among them. Thus, the most abundant kind, the pudding-stone, 

 is found to contain among its pebbles, beside those of crystallines, 



