406 Newer Pliocene and Post Pliocene Deposits 



and Sherbrooke Street, has apparently not been deposited on it^ 

 or has been swept away, so that the littoral sand and gravel rest 

 immediately on the boulder clay, and in some places on the rock* 

 {See Fig. 2.) 



Fig. 2. 



a Stratified Sand and Gravel with marine shells, and a large boulder, b Hard 

 Boulder Clay, c Silurian Limestone. 



The following is the assemblage of shells at this -place : 



Saxicava rugosa, (by far more abundant 

 than any other.) 



Mya truncata. 

 Tellina Groenlandica. 

 Astarte Lauren tiana. 

 Mytilus edulis. 

 Mya arenaria. 

 Tellina calcarea. 



Balanus crenatus. (Bal. miser of some 

 lists. It is usually attached to the mussel shells.) 

 Trichotropis borealis. 

 Bulla oryza. 

 Natica clausa. 



Spirorbis sinistrorsa, (attached to stones 

 and loose valves of Mya Truncata. 

 All these may be regarded as littoral, or circum-littoral shells, 

 the deep sea deposit being here absent. 



Between the slight ridge at the quarries, and another near the 

 house of James Logan, Esq., produced by a thick dyke of trap, 

 is a slight depression, in which excavations for drains have exposed 

 the richest collection of Post Pliocene shells that I have any- 

 where seen. In this flat, there occur sands with purely littoral 

 shells, as Mytilus edulis, Mya arenaria, &c., and sandy clay with 



