307 



Guppy Reprint 



i59 



There are plenty of soils in the Couva district and neighbour- 

 ing parts which would be improved b}^ the addition of this fossil- 

 iferous rock. As a road material it may serve in default of bet- 

 ter, but it would not be of any great durability, and could not 

 stand heavy traffic. 



I endeavored without success to obtain some information as 

 to dip and strike and the relations of the bed to other beds in the 

 neighbourhood. There was a kind of false bedding which ob- 

 scured the real relations of the strata — but as no other beds were 

 visible above or below I could not ascertain any other facts. 

 Still in order to exhibit the relations of the strata I subjoin a di- 

 agram which I hope will assist in making the general relations 

 clear. This shows that the Couva and Montserrat miocene shell 

 deposits were in course of formation at the same time as the lat- 

 ter part of the oceanic deposits. The subsequent folding disloca- 

 tion and upheaval have altered the apparent relations of the 

 formations. Until we know the ground better, and have detailed 

 information as to the outcrop, &c, of the geological formations 

 we cannot give a more definite Section than this approximate 

 one, which is only diagrammatic. 



Page 3 



The terms Eocene Miocene and Pliocene were originally 

 fixed by Lyell for the three great divisions of the tertiary strata 

 (see Principles of Geology 8th Ed. page 177 ; Elements 6th Ed. 

 page 187 ; and Student's Manual 1878 page 122) in accordance 

 with the percentage of recent species found in the formations so 

 designated. The percentage test though fundamentally a useful 

 one is not always free from difficulty in its application to partic- 

 ular cases, and the West Indian miocene formation is one of these 

 cases. And this arises in some degree from the fact that the 

 proportion of recent species varies with each observer. Accord- 

 ing to the list of names I give, amounting to about a hundred 

 species, there are not more than three or four still-existing spe- 

 cies in our miocene beds, and even these can easily be disposed of 

 by giving them other names which in most cases are ready to 

 hand. When we come to examine the shells we find a large 



