206 T. C. CHAMBERLIX GROUNDWORK OF EARTh's DIASTROPHISM 



solution curve — was accommodated at all depths to the conditions im- 

 posed by pressure, by the constitution of the material, and by other prop- 

 erties. The critical temperature, the solution-fusion temperature, rose 

 as depth increased, but the rate of rise was dependent on too many un- 

 known factors to permit a trustworthy determination, either at present or 

 in the past. The essential point here is that the part which heat played 

 in the complex action was that of a product rather than a primary deter- 

 minant. The high rigidity of the earth, now so well authenticated, seems 

 to point definitely to some such automatic mechanism as this. So equally 

 do the driblets of liquefied matter that have been forced to the surface, or 

 to the cool surficial zone, in all the geologic ages, past and present. The 

 working out of this automatic adjustment by the cooperating processes 

 is to be regarded as the attainment of the past billions of years rather 

 than millions of years. 



The Time oe the most effective diastrophic Action 



Among the strong contrasts between the two views of genesis under 

 comparison are those that relate to the time when the chief diastrophic 

 events took place. If the earth was at first a globe of gas, it collapsed as 

 fast as the radiation of its excess of heat permitted. The time consumed 

 in the process was relatively short, for radiation takes place in proportion 

 to the fourth power of the temperature, and the temperature in this case 

 was necessarily high, according to Lane's law. If, on the other hand, the 

 earth was formed by the ingathering of planetesimals, the process fol- 

 lowed the laws of orbital dynamics and the formative process was very 

 much slower. It may have taken three or four billion years. In this 

 long period of gradual upbuilding, the graded adjustments just described 

 should have had time to work out their mutual adaptations. 



In another respect, also, the contrast was striking. In the traditional 

 gaseo-liquid earth, diastrophism did not start until after the formative 

 process had ceased and encrusting had begun. In the planetesimal earth, 

 the diastrophism began with the earliest accessions and ran progressively 

 through all the formative stages, and through all later time. It appar- 

 ently grew in effectiveness during the main assembling of material, but 

 it appears to have declined when the accessions fell to a relatively in- 

 effectual rate. The most effective diastrophism thus fell witliin the for- 

 mative eons. The sum total of diastrophism in the whole earth body was 

 thus greatest during the formative eons. It is probable that during any 

 large fraction of tlie formative ages greater diastrophism took place, even 

 in the surficial shell, than during any of the later periods of equal length, 

 though this can not, perhaps, be affirmed with the same confidence, for it 



