128 GEOLOGY OF THE SECOND DISTRICT. 



The tertiary of Cliamplain is mineralogically composed, in the ascending order, of: 1st, a 

 stiff bhie clay ; 2d, a yellowish brown clay ; and 3d, of yellowish brown sand. The three 

 portions into which the formation is here divided is, however, of little importance, inasmuch 

 as the upper part of the clay owes its color principally to weathering, rather than to any im- 

 portant difference in its composition. The whole contains a sufficient amount of carbonate of 

 lime to effervesce briskly with acids, though there appears to be less in the inferior, than in 

 the superior part. Sand begins to appear in the yellowish clay, and increases gi-adually until 

 it predominates, and finally becomes a pure sihceous sand. 



This formation, as it appears along the shores of Lake Champlain and the St. Lawrence 

 river, is not calculated to excite much attention ; consisting, as it generally does, of beds of 

 clay, without fossils, or any thing peculiar to attract attention. It is only where the observer 

 happens to meet with those portions of it which are fossiliferous, that his interest will be 

 much excited. Of the fossils which have been observed, there are about twenty species in 

 all. They are, however, very unequally disseminated, and there are only a few localities 

 which contain numerous species. The two species generally contained in the formation, are 

 the Saxicava rugosa and Tellina groenlandica. In most places along the shore of the lake, 

 and of the St. Lawrence river, these two fossils may be found on careful inspection. They 

 are in an unmineralized state, rarely filled with clay. In addition to the two species of Mol- 

 lusca I have just mentioned, the following I have discovered as existing principally at two 

 places, viz. at Port Kent, and Beauport near Quebec : Tritonium anglicum, Tritonium forni- 

 catum, Mytilus edulis, Pecten islandicus, Mya truncata, M. arenaria, Tellina, (two species,) 

 Turritella, Nucula portlandica, Buha, etc. (See Plates I. and II.) 



Denudations tvhich this mass has suffered since its deposition. 



As has been stated above, the formation in general does not present any striking characters 

 by which it would excite particularly the attention of the geologist, except at a very few 

 points ; and it is at those points that it appears highly charged with fossils. Now we may 

 inquire the cause of this remarkable circumstance. It is true that molluscous animals are 

 found congregated at places which are the best adapted to their organization ; and the inquiry 

 might arise, whether it was owing to causes connected with structure and function, that so 

 few locahlies are to be found where those remains are deposited ; or whether they may not 

 have been drifted into their present position ? 



In answer to these questions, I remark, that the whole deposit bears evidence of having 

 been formed under quiet and undisturbed waters, and that the entire formation consists of 

 clay, sandy clay and sand ; and that it is in the mixture of clay and sand, or towards the 

 upper portion of the formation, that the remains principally exist : where, therefore, a mere 

 bed of clay is found, we have no fossils. Again, the fact that they preserve their markings 

 and edges entire, and valves in place, though many are exceedingly frail, forbids the idea 



