333 



Guppy Reprint 



185 



the Caroni series as laid down by Wall and Sawkins in the Geo- 

 logical Report on Trinidad, i860, pp. 43, 45. The strata under- 



Page 2 



lying the Shellbed pass downwards into fine-grained soft rocks 

 characterized by the Foraminifer PlanorbuU?ia lamata. This po- 

 sition is correctly indicated in the Diagram at p. 30 of The Pro- 

 ceedings of the Society illustrating my Paper on Recent Geologi- 

 cal Discoveries (Vol. XII., 191 2). These strata are there indi- 

 cated by the letter I13 and I12 (Page 9 of separate copies.) 



Interstratified with the mudbeds are strata of a more perme- 

 able quality, consisting of fine sandstones, and these pass in places 

 into gravel beds sometimes indurated and these sandy and gravel 

 beds allow of the percolation and storage of water whence the 

 springs which are common in this country. The lower portion 

 of the Caroni Series especially contains gravel beds which seem 

 to overlie the cretaceous rocks. In fact the gravelly and sandy 

 beds of the Tertiaries are here chiefly derived from the cretaceous 

 series. I did not see the lower miocene beds (the Tamana Ser- 

 ies) exposed anywhere in this locality, and it is possible that they 

 may not have been developed here, or they may be in part or 

 wholl}^ represented by the strata underlying the Shellbed. 



On one point it seems necessary to give a caution. That is, 

 the diagrams attached to my papers are not intended in any way 

 as finished plans or sections. Thus the diagram of the Orbitoides 

 Bed (Proceedi??gs, p. 20/f) is intended only to show approximate- 

 ly the position of that bed ; it is not drawn to scale nor is it in- 

 tended to show the dip or the relations of the other beds. The 

 diagram is sufficient for its purpose. The faults shown in the 

 diagram of which it is a modified copy (Journ. Geol. Soc, 1892, 

 Page 522) are not indicated. Again the diagram at Page 9 of 

 my Paper on Recent Geological Discoveries, (page 30 of Proceed- 

 ings) is purely diagrammatic. It shows correctly the relations 

 of the strata so far as yet ascertained. But these diagrams are 

 merely generalized sections, and for convenience the height 



Page 3 



is greatly exaggerated and no attempt is made to show 



