320 I /it Aliniiril II (rinlix/i.sf. NonciiiIi.t. 1>*fM 
1:111(1 liy till- >ii|)i'r;ul(U'tl wi'ijilil :i('tiii<i t:iii<z;('iiti:ill\ towMid tlu' 
shores. In \\\v opposite hemispliiTt' :i new i'(|iiilil)iiiiiii would 
t'stnhlisli itself l»y the elevation of the isen-hottoni and depression 
of the land. Tiiis would, in some de<rree. neutiali/.e the relative 
ditferences of land and water areas to wliicli the shiftinj; of the 
seas would jjive rise. It is to Ite remembered that tln' intense 
pressure at the poles during periods of maximum "[hiciation * 
Avould precipitate erusttd convulsions when the contractile tension 
due to the radiation of internal heat sh(ndii have l)ecome sutfi- 
eiently j^reat. These complex factors wouhl all come into play 
periodically with the pei'ioilic recurrence of suitaltle astronomical 
conditions. 
Then' is yet another cause of periodicity which has oc- 
curn'<l to me. In the deeper parts of the ocean, the hydro- 
static pressure must l»e enormously great. This pressure must 
foi'ce water very deeply into the rocky interstices of the ocean's 
floor, perhaps so deeply that its permeative power by c-apillarity 
is vastly increased (Daubree '(Jeologie Experinientale. ' p. 274). 
This water cominir in contact with the heated rocks of the deeper 
crust would be vaporized and would also facilitate the evo- 
lution of explosive gases. These i'xpansil)le i)roducts would i)ress 
with tremendous force against their inclosures. and the crust 
would slowly yield to the irresistible pressure. This crustal 
movement would continue for a time nntil the original int<'rstices 
should have swelled out into fissures sutlicieutly wide to admit 
the expansive products to escape as fast as they were formed. A 
period of (piiescence. so far as this force is concerned, would then 
ensue until the gaps were filled in with sediment when the process 
would again l>e renewed. If the erosion of the land during the 
period of ({uiet Avere just sulHcient to till up the gajjs we woulii 
then hav«' the ideal conditions suggested at the beginning of this 
article. It should be remembered that the expansixc force here 
considered would have a powerful tangential component which 
would react landward in each direction tending to produce 
continental upheavals. Such movements would cause a sub- 
mergence of the ocean's l)ed. and this Itetl would lie still 
farther depressi'd >)y the superadded weight of the inrush- 
ing wati'rs. Thus tliei'c wonhl l>e an indefinite reciprocal 
action l»etween the two initial tendencies, each elevation intensi- 
fying its correlated depression, and each depression augmenting 
