ON ITS EXTERIOR. SPRINGS OF VAPOUR AND GAS. 211 



There is no part of the earth's surface where hot 

 springs, salses, and eruptions of gas are found, for 

 which we now possess such excellent and detailed che- 

 mical examinations as those for Iceland, which we owe 

 to the sagacity and persevering labours of Bunsen. 

 Nowhere, so far as we know, are such varied actions 

 of chemical decomposition, formation, and transform- 

 ation to be observed over so great a tract of country, 

 and probably in such near proximity to the surface. 



Passing from Iceland to the American continent, we 

 find in the state of New York, in the district of Fre- 

 donia, not far from Lake Erie, in a basin of strata of 

 Devonian sandstone, an immense number of springs 

 of inflammable gas, (springs of carburetted hydro- 

 gen), breaking forth from fissures, and sometimes used 

 for gas-lights ; other springs of combustible gas, as at 

 Eushville, take the shape of mud-cones ; others, as in 

 the valley of the Ohio, in Virginia, and at the Ken- 

 tucky river, contain at the same time common salt, and 

 in such case are connected with weak naphtha-springs. 

 Passing to the south of the Caribbean Sea, on the north 

 coast of South America, ten miles S.S.E. of the port of 

 Cartagena de Indias, near the pleasant village of Tur- 

 baco, a remarkable group of salses, or mud-volcanoes, 

 presents phenomena which I was the first to describe. 

 At this place, where a glorious view of the colossal 

 snow-covered mountains (Sierras Nevadas) of Santa 

 Marta is enjoyed, there rise on a desert space, in the 

 midst of the primeval forest, 18 or 20 " volcancitos." 

 The larger of these cones of dark grey are from 19 to 

 23|- feet high, and fully 85 feet in diameter at their 

 base. At the top of each cone there is a circular 



p 2 



