Vol. 68.] THE GEOLOGY OP COSTA EICA. 103- 



7. Geology of a Paet of Costa Hica. By James Romanes, M.A., 



P.G.S., Christ's College, Cambridge. (Eead December 6th, 



1911.) 



[Plates VIII & IX.] 



Contents. 



Page 



I. Introduction 103 



II. Previous Literature 105 



III. Greology of the Cerro Candelaria 105 



{a) TheSedimentiiry Series. 

 {h) The Igneous Pocks. 



IV. Cartago and the San Jose Valley 113 



(a) Cartago. 

 (6) San Jose. 

 (c) El Brazil. 

 id) Cebadilla. 



V. The Pacific Coast ; 123 



{a) Barranca. 



{b) The Avangares Mines — Manzanilla. 



((?) Gulf of Nicoya. 



VI. The 'Boulder Clays' of Costa Pica 133 



VII. Summary and Conclusions 136 



I. iFTEOBUCTIOlsr. 



At the suggestion of Mr. W. J. Le Lacheur, P.G.S., and Dr. J. E. 

 Marr, P.E.S., and assisted by a grant from the Worts Fund, I 

 undertook at the beginning of the year 1910 a journey to Costa 

 Eica, with the view of studying the geology of parts of that country. 

 Most of the time was spent on the Pacific slope, on which even less 

 work of a detailed nature seems to have been done than on the 

 Atlantic side. Towards the end of my visit I was able to devote a 

 short time to certain parts of the Atlantic slope : unfortunately 

 the box containing all the most important specimens from that area 

 was lost in transit. The present paper, therefore, deals principally 

 with the country lying to the west of San Jose, down to the Gulf of 

 Mcoya. 



In a region comparatively so little known geologically, and of 

 which the maps are on a very small scale and not altogether 

 reliable, detailed work in the three months which I had at my 

 disposal was out of the question. Therefore, the account of my work 

 which follows is not meant to represent any completed investigation, 

 but simply a description of the formations and exposures met with, 

 published in the hope that it may prove of use to future workers. 

 I trust at some later date to be able to publish a more complete 

 account of the palaeontology of the fossiliferous deposits than 

 appears in this paper, and to deal more fully with their bearing 

 on the wider questions of Central American geology. 



