CHAPTER I. 



ST. JAGO, IN THE CAPE DE VERDE ARCHIPELAGO. 



Rocks of the lowest series. — A calcareous sedimentary deposit, with 

 recent shells, altered by the contact of superincumbent lava, its hori- 

 zontally and extent — Subsequent volcanic eruptions, associated with 

 calcareous matter in an earthy and fibrous form, and often enclosed 

 within the separate cells of the scorim — Ancient and obliterated 

 orifices of eruption of small size — Difficulty of tracing over a bare 

 plain recent streams of lava — Inland hills of more ancient volcanic 

 rock — decomposed olivine in large m,asses — Feldspathic rocks beneath 

 the upper crystalline basaltic strata — Uniform structure and form of 

 the more ancient volcanic hills — Form of the valleys near the coast 

 — Conglomerate now forming on the sea beach. 



The island of St. Jago extends in a NNW. and SSE. 

 direction, thirty miles in length by about twelve in 

 breadth. My observations, made during two visits, were 

 confined to the southern portion within the distance of 

 a few leagues from Porto Praya. The country, viewed 

 from the sea, presents a varied outline : smooth conical 

 hills of a reddish colour (like Red Hill in the accompany- 

 ing woodcut), 1 and others less regular, flat-topped, and 

 of a blackish colour (like A, B, 0,) rise from successive, 

 step-formed plains of lava. At a distance, a chain of 

 mountains, many thousand feet in height, traverses the 

 interior of the island. There is no active volcano in 

 St. Jago, and only one in the group, namely at Fogo. 



1 The outline of the coast, the position of the villages, streamlets, 

 and of most of the hills in this woodcut, are copied from the chart 

 made on board H.M.S ' Leven.' The square-topped hills (A, B C,&c.) 

 are put in merely by eye, to illustrate my description. 



