TIME AND CHANGE 



Archsean rock. How distinctly it looked like a new 

 day in creation where the horizontal, yellowish-gray 

 beds of the Cambrian were laid down upon the dark, 

 amorphous, and twisted older granite! How care 

 fully the level strata had been fitted to the shapeless 

 mass beneath it! It all looked Kke the work of a 

 master mason; apparently you could put the point 

 of your knife where one ended and the other began. 

 The older rock suggested chaos and turmoil; the 

 other suggested order and plan, as if the builder had 

 said, &quot;Now upon this foundation we will build our 

 house.&quot; It is an interesting fact, the full geologic 

 significance of which I suppose I do not appreciate, 

 that the different formations are usually marked off 

 from one another in just this sharp way, as if each 

 one was, indeed, the work of a separate day of crea 

 tion. Nature appears at long intervals to turn over a 

 new leaf and start a new chapter in her great book. 

 The transition from one geologic age to another 

 appears to be abrupt : new colors, new constituents, 

 new qualities appear in the rocks with a suddenness 

 hard to reconcile with Ly ell s doctrine of uniform- 

 itarianism, just as new species appear in the life of 

 the globe with an abruptness hard to reconcile with 

 Darwin s slow process of natural selection. Is sudden 

 mutation, after all, the key to all these phenomena? 

 We ate our lunch on the old Cambrian table, 

 placed there for us so long ago, and gazed down 

 upon the turbulent river hiding and reappearing in 

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