268 T.C. Chamberlin — Jones's Criticism of 



dynes at the surface and 30 X 10 11 dynes at the center, 

 with a mean rigidity of 2% times that of steel. 12 



What follows the rigid-elastic state when the strain 

 limit is passed? — It has now been amply shown by pro- 

 tracted researches on glacier motion, solid rock-now and 

 dynamic metamorphism, that while the viscous state and 

 even liquefaction may, in particular cases, follow when 

 the strain limit is reached, and also that faulting, granu- 

 lation, or massive shear may follow in others, the more 

 widely prevalent, more characteristic and more funda- 

 mental sequence, when the pressure is not over-intense 

 and the time is ample, is the passage of one elastico -rigid 

 state into another elastico -rigid state. The new state is 

 often more perfectly and highly organized in respect to 

 the elastico-rigid property than the previous state. Thus 

 movement may go on to great lengths, in time, simply by 

 this succession of solid states, as in the case of glacial 

 flow and dynamic metamorphism. The earth seems to be 

 progressively passing into more and more highly organ- 

 ized states of elastic rigidity, or in other words, meta- 

 morphism is in progress in the solid earth. This change 

 seems to be effected largely by idiomolecular action, i.e. 

 individual action atom by atom or molecule by molecule. 

 The main mass remains solid while the shifting atoms or 

 molecules act as individual elastico-rigid organizations. 

 And further, even this individual action is not necessarily, 

 and perhaps not normally in the depths, liquid action, nor 

 gaseous action, for liquids and gasses are assemblages of 

 molecules, while these shifting atoms or molecules act 

 individually. As such individuals, they are, under the 

 new views, elastico-rigid mechanisms of an ideal type. 

 In being individually detached from its hold on one crys- 

 tal or particle, the atom or molecule is probably shot 

 through the dynamic — not bodily — resistances of the 

 space lattices or equivalent opennesses, until it is arrested 

 and oriented by a new fixed attachment. The rigido- 

 elastic arrangements of the countless atoms and mole- 

 cules in the solid earth body are held to be giving way as 

 differential stresses rise to the requisite degree, and thus 

 to be passing from old to new relationships. Thus a 

 "flow" like that known to affect glaciers and rocks under- 



12 W. Schweydar ; ' ' Tiber die Elastizitat der Erde, ' ' Naturwissenschaf ten, 

 Part 38, p. 22, 1917, Potsdam, Germany. 



