206 REACTION OP THE INTERIOR OP THE EARTH 



also in countries where neither trachyte nor other volcanio 

 rocks are present at the surface. In the Cordillera of 

 Quindiu, at an elevation of 6830 English feet above the 

 sea, I have seen sulphur deposited in mica slate from hot 

 sulphureous vapours; ( 197 ) and to the south of Quito, in 

 the Cerro Cuella, near Tiscan, the same rock, which was 

 formerly regarded as primitive, contains an immense deposit 

 of sulphur imbedded in pure quartz. 



Of gaseous emissions, those of carbonic acid are, as far 

 as we yet know, the most numerous and the most abun- 

 dant. In Germany, in the deep ravines of the Eifel, in 

 the vicinity of the Laacher-See, in the crater-like valley of 

 Wehr, and in Western Bohemia, exhalations of carbonic 

 acid gas appear as a last effort of volcanic; activity, in and 

 near its ancient foci in an earlier state of the globe. 

 With the high terrestrial temperatures of that period, and 

 the numerous fissures which were not then filled up, tlie 

 processes which we have here described, and in which carbonic 

 acid gas and hot steam mingled in considerable quantities 

 with the atmosphere, must have acted far more powerfully ; 

 and then, as Adolphe Brongniart has shewn, the vegetable 

 world must have attained everywhere, almost independently 

 of geographical position, the most luxuriant development and 

 abundance. ( 198 ) In this constantly warm and moist atmos- 

 phere loaded with carbonic acid gas, plants must have found 

 both the stimulus and the superabundant nourishment, which 

 piepared them for becoming the materials of those nearly 

 inexhaustible stores of coal, on which the physical power arid 

 prosperity of nations are based. Beds of this fuel are 

 accumulated in basins in particular parts of Europe, in the 

 British Islands, in Belgium, in France, on the Lower Bhine, 



