1865.] DAWSON — POST-PLIOCENE DEPOSITS. 85 



It must be observed that though the clays at Riviere-du-Loup 

 are more recent than those of Montreal, they are still of consider- 

 able antiquity. They must have been deposited in water perhaps 

 fifty fathoms deep, and the bottom must have been raised from 

 that depth to its present level ; and in the meantime the high 

 cliffs now fronting the coast must have been cut out of the rocks 

 of the Quebec group. 



The order of succession and characteristic fossils seen on the 

 banks of the Petite Riviere-du-Loup may be stated as follows, 

 in descending order : 



1. Gravel seen on sides and tops of ridges. 



2. Stratified sand and clay — Buccinum undatum and Tellina 



Grcenlandlca. 



3. Bluish sandy clay, stones, and boulders. Balunus Hameri, 



Rhynchonella ptittacea, Pccten Islandicus, Leda tenuisul- 

 cata, L. minuta, Tellina calcarea, Astarte compressa, 

 Saxicava rugosa, Acmoea casca, Scalaria Grcenlandlca, 

 Natica clausa, Buccinum scalariforme, Bryozoa on stones, 

 Foraminifera, &c, &c. 



4. Stiff reddish clay with stones and boulders — Leda truncata, 



L. limatula, Nucula tenuis, Tellina calcarea, &c. 



At Tadoussac, opposite to Cacouna, where the underlying for- 

 mation is the Laurentian gneiss, the Post-pliocene beds attain to 

 great thickness, but are of simple structure and' slightly fossiliferous, 

 The principal part is a stratified sandy clay with few boulders, 

 except in places near the ridges of Laurentian rocks. This forms 

 high banks eastward of Tadoussac. It contains a few shells of 

 Tellina Groenlandica and Leda truncata. It resembles No. 2 of 

 the above sectional list, and has also much of the aspect of the 

 Leda clay, as developed in the valley of the Ottawa. On this clay 

 there rest in places thick beds of yellow sand and gravel. 



At Tadoussac these deposits have been cut into a succession of 

 terraces which are well seen near the hotel and old church. The 

 lowest, near the shore, is about ten feet high ; the second, on 

 which the hotel stands, is forty feet; the third is 120 to 150 feet 

 in height, and is uneven at top. The highest, which consists of 

 sand and gravel, is about 250 feet in height. Above this the 

 country inland consists of bare Laurentian rocks. These terraces 

 have been cut out of deposits, once more extensive, in the process 

 of elevation of the land ; and the present flats off the mouth of the 

 Saguenay, would form a similar terrace as wide as any of the 



