E. W. Hilgard on Mallet’s Theory of Vulcanicity. 541 
of the “viscous couche;” and if these experienced local re- 
fusion, the fused matter may well be presumed to have often 
been disposed of by eruption through fissures or volcanic vents, 
rather than by overcoming, downward, the inertia of the vis 
cous couches. This mode of action seems to me likely not 
only to afford a more copious, but also a more constant or last- 
ing source of supply, than the supposed crushing of solid rock, 
and appears especially applicable to the case of large fissure 
eruptions 
Among the greatest services rendered by Mallet’s (or, in this 
connection, Wurtz’) theory, is the unstrained explanation of 
uurope. In its application to the formation of synclinoria 
especially, the principle works most instructively and satisfac- 
torily. 
were comparatively localized and eg and. psa gp Si 
i their results such as W 
ocali 
not successfully resist the influence of an advantage of lever- 
ve icable that 
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