1831.] 
331 
Note on the Volcanos of Asia. 
The action of volcanos, properly so called, thus manifests a close connection with 
the formation, sometimes sudden, sometimes slow, of beds of gypsum and of rock 
salt, including petroleum, condensed hydrogen, sulphuretted iron, and occasionally 
(as at Rio Huallaga, to the east of the Peruvian Andes), large musses of gnlcnu ; — 
also, with the origin of mineral springs ; with the deposit of metallic groups at dif- 
ferent epochs irorn the bottom upwards, either in veins, in masses, or in intimate 
combination with the rock in the neighbourhood of metalliferous veins; with 
earthquakes of which the effects must not be regarded as purely mechanical, for 
tin y are often accompanied by chemical phenomena, such as the emission of irre- 
spirable gas, smoke, and luminous matter ; and lastly, with the upheavings, cither 
instantaneous or gradual, of large portions of the earth’s surface. 
■flie intimate connection between the above described phenomena, derived from 
regarding volcanic energy as the action of the interior of the globe upon its outward 
coat, has served to explain in the present day, a number of geological and physical facts 
which before appeared inexplicable. The analogy of facts well recorded, and the close 
observation of recent phenomena in various places, lead us by degrees to guess what 
must have happened in the remote ages of the world. Volcanicity , or the in- 
fluence exercised by the interior of a planet upon its exterior, in the different stages 
°t its cooling, through the inequalities of aggregation, of fluidity and solidity, in 
which its component parts are found, is very much weakened in the present day ; — 
fliis action from within outwards is now restrained to a few points, intermittent in 
bine, less frequently changed in locality, much simplified in its chemical effects, 
producing only rocks on a small scale around small openings or crevices; and 
exhibiting its power at great distances only in feeble quakings of the crust of the 
J-Jobo in particular directions, which have remained the same for ages past. 
I’ 1 the time immediately prior to the existence of the human race, the action of 
tin 1 interior oftheglobe upon the crust, which was then increasing in bulk, must have 
modified the temperature of the atmosphere, so as to render the whole of the globe 
habitable to those productions which are now regarded as tropical; since when the 
effects of radiation, of cooling on the surface, and of the relative position of the 
c,l ith to the sun, have tended to limit the diversity of climates to corresponding geo- 
graphical position. 
It was also in these primitive ages, that the elastic fluids, perhaps, the most 
powerful agents of volcanic force, bursting through the oxidated and congealed 
crust , opened crevices therein, and introduced not only in the shape ot dykes, but 
‘ n all sorts of irregular masses, other matter of great density, such as ferruginous 
hasalt, melaphi/reSy and metals. It is the difference of local constitution that 
Causes the discrepancies between the observed acceleration of the pendulum and the 
trigonometrical measures taken on the earth’s surface. The epoch of the greatest 
geological revolutions was precisely that, when the communications between the 
^ f l u id interior of the planet and its atmosphere were most frequent, and acting upon 
ti‘ e greatest number of points : hence it may be said, the tendency to establish these 
Communications has caused the elevation, in different ages and in diffeient directions, 
(apparently determined by the diversity of the epochs,) upon long crevices, of, first 
^ le 5 rea t mountain chains, such as the Himmalaya and the Andes ; then the * ,) oun 
Vinous ranges of a less elevation, and lastly the gentle undulations which em >elhsh 
the landscape of our plains. As a proof of these upheavings, and a record (according 
C°the ingenious views of M. Eliede Beaumont) of the relative age of those moun ains, 
I ha *e seen in the Andes at Cundinamarca, extensive formations of sandstone sprea - 
n t' across the plains of Magdalena and Meta, almost without interruption o 
* Q dl400 to 1600 toises high ; and lately again in the north of Asia, in the Iral c u , 
