152 Remarks on Professor Eaton'' s Communication. 



rocks, with stones not mineralized ;" and 'Jiuviatile deiritus,^ 

 or " post diluvian accumulations of mud. sand, and salt." 

 Nay, even Werner himself made the following division of 

 alluvium which must have had a reference to " the relative 

 ages of different layers." 



" 1. Mountain alluvial formations. 



a. On the summits of mountains. 



h. On the sides of mountains and at the foot of moun- 

 tain rans;es. 



2. Alluvial formations of low or flat lands." 



If then we are guilty of neglect, it is neglect of Mr. 

 Eaton's division of alluvium into " primary and secondary 

 alluvion." But our ohject was not to notice all the attempts 

 to divide this stratum that had been made by geologists ; but 

 to notice that which appeared to us the best: and we then 

 believed, and still believe, that Mr. Conyb^are has been so 

 happy as to seize upon such characters for his diluvium 

 and alluvium, as are easy of application, and in strict 

 accordance with those distinctions that actually exist in 

 nature. We believe too, that until geologists adopt these 

 terms, their descriptions of the newest formations will be 

 extremely vague and unintelligible. Mr. Eaton's primary 

 alluvion is distingushed from his secondary alluvion by the 

 absence of vegetable remains, in the former. Now sup- 

 pose he comprehends in the general term alluvion, all the 

 unconsolidated strata — which extensive meaning we believe 

 has usually been affixed to the term — and let us inquire what 

 part of these strata will be included under his primary allu- 

 vion. For convenience, let us use the terms employed by 

 Mr. Conybeare, in the work under consideration, as our 

 guide in answering this question. No doubt will exist but 

 his alluvium is comprehended in Mr. Eaton's secondary 

 alluvion, because it abound? in vegetable remains. His 

 diluvium also belongs to the same place : for this also con- 

 tains beds of fossil wood : and these two formations consti- 

 tute the greater part of what is usually called alluvion. 

 We come next to the alternations of the fresh water and 

 upper and lower marine formations, a few of the varieties of 

 which are not consolidated ; yet in nearly all of them, if 

 not all, vegetable remains occur. Certainly they occur in 

 great quantity in the London Clay and Plastic Clay, which 

 lie beneath the formations just mentioned, and therefore, if 



