Geology of a Part of Costa Rica

Abstract

I. Introduction. At the suggestion of Mr. W. J. Le Lacheur, F.G.S., and Dr. J. E. Marr, F.R.S., and assisted by a grant from the Worts Fund, I undertook at the beginning of the year 1910 a journey to Costa Rica, 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 José, down to the Gulf of Nicoya. 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 palæontology of the fossiliferous deposits than appears in this paper, and to