14 



Anollier possibility wliich we miglit conceive, would be tliat 

 under tlie influence of these tensions the covering sedimentary masses 

 in the G. S. were upheaved. 



That might ultimately lead to the formation of overthnisl [)lanes 

 (nappes de charriages), through a lateral bulging out of the I'aised 

 up masses. 



At last a local rupture through the enveloping strata might give 

 birth to volcanic eruptions, which then might be sub-nuu'ine. 



We might conceive the mechanism of volcanism in ihis way. 



When by the action due to isostatic influences, a fissure or faull 

 be engendered in the region of the steep flank of the (t. A., or when 

 in the raised up part of the (t. S. a ruptui'e should result from the 

 high tensions prevailing there, the vajiour tensions existing in the 

 vicinity of such faults or fissures would discharge themselves entirely 

 or partly in such fissure or fault. 



Part of the plastic (or liquid) rock would be carried along, as 

 water overcharged with carbon-dioxide is carried along by sudden 

 and sufficient relief of pressure. 



The subsidence of sedimentary deposits ever continuing, through 

 accumulation of the products of erosion in the G. S., water (vapour-) 

 charged sediments would e\er and anon be conducted into the 

 regions of excessive high temperatures; this might account for the 

 periodicity of volcanism '). 



Thus the appearance of volcanism might be expected in those 

 regions of the earth, situated outside the G.S., which by some cause 

 or other, are moving in centripetal direction or have lately done so. 



Should on this basis a solution be offered for a certain amount 

 of questions regarding the mechanism and origin of volcanism, the 

 question still remains whether it may be considered plausible that 

 the sea wafer imprisoned in the pore spaces of sedimentary strata, 

 may be there still when these sediments have reached depths where 

 liquefying temperatures are reigning. 



The vapour tensions, it might be argued, there prevailing, must 

 have exjielled all the water once occluded in the pore space of these 

 sediments, long i)efbre such deposits could have reached the \icinify 

 of the regions of those high temperatures. 



It is known however that the frietional resistance of liquids in 

 capillary channels is considerable, being for a given flow, per unit 



1) I might be allowed to draw the attention to the fact that the absence of 

 water in liquid slate on the moon, and the absence of erosion, sedimentation and 

 isostatic movements as a consequence of it, may perhaps stand in causal relation 

 to tlie absence of periodicity of lunar volcanism, in contrast witli lerrestrial volcanism. 



