DRY LAND IN GEOLOGY COLEMAN. 269 



followed without mishap from the stage of a cooling gas to that of 

 a liquid, and then of a solid, would result in a correct spheroid of 

 rotation. The lithosphere thus formed would be covered by an un- 

 broken hydrosphere, followed in its turn by an atmosphere. A good 

 workman would certainly have come close enough to the ideal form 

 of his world to prevent errors amounting to 60,000 feet. A properly 

 manufactured world, following the orthodox nebular process, would 

 be completely covered by an ocean 8,000 or 10,000 feet deep. 



This ideal world without a continent or an island would have 

 avoided many difficulties. Land animals, blundering, bloodthirsty, 

 even cannibal in their crude instincts, could never have existed. 

 The ocean itself might never have been inhabited if life originated, 

 as is commonly supposed, under shallow-water conditions. How 

 quiet and peaceable such a world would have been ! One almost longs 

 for it under the turmoil of present conditions. 



A w^orld without land would have had its disadvantages, however. 

 There could have been no geologists and no geology. 



But it is idle to speculate as to the possibilities of a landless world. 

 The blunder was committed and the lithosphere was so far warped 

 out of shape that more than a quarter of it rises above the sea. One 

 might inquire, however, whether the blunder might not have been 

 rectified by providing more water, so as to drown out the objection- 

 able lands. We know that there have been times when much of the 

 present continental area was encroached on by the sea. Was there 

 more water then, or was it merely differently arranged? Large 

 amounts of water are withdrawn from circulation by the hydration 

 of various minerals. Are they balanced by the amounts restored as 

 juvenile waters and the steam from volcanoes, assuming, of course, 

 that volcanoes give off steam and not ammonium chloride? Prob- 

 ably most geologists take it for granted that the amount of water on 

 the globe is nearly constant from age to age. 



The existence of dry land at all when there is so much water on 

 the earth is a profound mystery not even plausibly explained by the 

 nebular hypothesis, since it demands an inexcusable irregularity in 

 the working of the nebular machinery. 



HAVE OCEANS AND CONTINENTS EVER CHANGED PLACES? 



Admitting that in the beginning the lithosphere bulged up in 

 places, so as to form continents, and sagged in other places, so as to 

 form ocean beds, there are interesting problems presented as to the 

 permanence of land and seas. All will admit marginal changes 

 affecting large areas, but these encroachments of the sea on the conti- 

 nents and the later retreats may be of quite a subordinate kind, not 

 implying an interchange of deep sea bottoms and land surfaces. The 

 essential permanence of continents and oceans has been firmly held 



