ON THE THEORIES OP ELEVATION AND EARTIIQUAKESt 33 
•mer 
Report on the Geological Tlmrxes of Elevation and Earthquakes. 
By William Hopkins, Esq., M.A., F.R.S., ^c. 
and Thmrics of Volcanos; and on the Form, 
f EarUi's solid crust, assuming the for 
jimaitg of the whole terrestnal mass. ^ • '' 
Section I. On the Plmmmma and Theories of Volcanos. 
phenomena ofelecation, and tlie 
fe« ^ "‘"y. attributable, would' eecu. to beTmper- 
^ e attempt to explain the origin of the forces which have 
Stb/fromSr I mechanical effect, 
^ultmg from them. I shall therefore avail myself of the ranee which I 
making this Uetwrt to consider 
* '“"5' speculating ou the canscsThich 
’Tf 'P"'-'"’’ naturally W wTefcr^ 
have foTOrir aL'! nature of thoae which 
ou“L™tio„lT ouTOUsIycharaeteriae the aurface of the earth, 
h^vS Z ‘".aarsttiig volcanos as likely to indicate the agency 
oi. 0. S t fcrZZ .“.ir*™” ''‘‘™ frequent 
appS’vTniil^Z Z ‘f'»‘™‘«."f'na»ae»ofrock which have been 
over tSsnS^il! r so‘l‘U'e«ta'-y deposits, or ejected 
be of iffm-niis nr*^’* whicli arc now universally allowed by geologists to 
the present ''"‘tli the effects of volcanic action at 
ulS of e Wt the idea that the gcnml phm- 
tera of volcanos -inrl fhfv ^ “tsLance, into such cojittiderations on the oharac- 
on the subieot of tmodes of action as may appear to l>ear immediately 
1 VS ^ P >£enomena of elevation generally. ^ 
caritvof contained in u 
we are here ohII I ^ eurtli. The most important characters which 
d ) T 1 l^r following:- 
with the cxifirnL'*Sr°h^'''”'”^ ‘lirect communication 
maintained in a state of fluidity by ite elevated 
»9 constantlv'tflltin w such that the fonnation of elastic gases 
siderable depth beneSuVsuriW ^ 
teoiperahlre these gases are capable of exerting at the high 
2 - With re«i)Pr>f ♦ ts. ^ "'hich they are generated is extremely great, 
an essential rlinM f° cavity, wo may observe that its rent is 
termed volcnmr ,} which the mode of action more especially 
different omni.tna ^^^spectiug the dimensions of the cavity, very 
matter of ad »'nt« l>®en maintained. Some have considered the fluid 
fluid iitunlena cnmuiMnicate with, or rather to be a part of, a cen- 
^ Solid shell of n f the great mass of the earth, and enveloped by 
sCld f r.? in UuckncBs ; while othera have 
fluid uuclpfi^ udently of theoretical views respecting the existence of a 
184,y -» a a communication exists bettveen volcanos not too far re- 
