1856.] 



ANSTED — COBRE LODE. 



145 



Structure of the Country. — Commencing with the plateau on 

 which the town is built, we find towards the south a considerable 

 mountain-chain, consisting of highly calcareous porphyritic rocks, 

 passing into and associated with basalts and a peculiar conglomerate, 

 while to the north, at some distance, are hard beds of limestone. I 

 submit a general section (diagram fig. 1) through the eastern part of 

 the island of Cuba, crossing the mining district, which will give a suffi- 

 cient idea as to the allocation of the beds. It will there be seen that 

 the beds of greenstone and porphyry appear to overlie the conglome- 

 rates, green grits, and hard limestones, and these in turn are overlaid 

 by newer tertiary limestones developed near the coast. For this 

 section I am partly indebted to M. Quintana (Government Inspector 

 of Mines of the district), who had crossed the island as far as Holguin 

 in the central plains. My own observations were confined to the 

 mining district and the north and south coasts. 



Fig. 1. — General Section across the Eastern End of the Island of 



Cuba. 



(Length of Section about eighty miles.) 



(Gold.) 

 c. Conglomerate. I. Limestone, p. Porphyry. s. Syenite. g. Granite. 



The mineral veins occur in the large-grained porphyry already 

 alluded to, near its contact with a coarse conglomerate, both con- 

 glomerate and porphyry being extremely calcareous. The general 

 direction of the mountain- ridges and watershed, the strike of the 

 porphyries and conglomerates, and also the strike of the lodes, are 

 all approximately east and west, this being also the direction of the 

 south-eastern coast of the island of Cuba. 



The dip of the lodes is to the south, and that of the bedded rocks 

 to the north, but the former are much more nearly vertical than the 

 latter. Towards the east the coast range is syenite, and it is not un- 

 likely that this syenite extends to or is repeated in the west side of the 

 harbour, south of the mines. Of this, however, I have no positive 

 proof. It is worthy of notice that the whole of the mountain-tract 

 forming the south-eastern extremity of Cuba, is remarkably subject to 

 earthquake action, two months rarely elapsing without a shock, while 

 towards the centre of the island and to the west no shocks are ever felt. 



The surface of the ground, both in the neighbourhood of the 

 mines and elsewhere in this part of Cuba, is so covered with tropical 

 vegetation, and the ground for the most part so impracticable, that 

 any continuous survey is impossible, so that many observations, else- 



