THE SCIENCE OF OBSERVATION. 



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transported by temporary and permanent currents thousands of miles 

 away, where it is deposited in the more quiet waters of the ocean. In 

 this manner the Mississippi has been shown to deposit a cubic mile 

 of mechanically transported material in a little over a century. What 

 shall we say of the effects produced on the continents and oceans by 

 thousands of rivers, each doing its proportionate share of work and 

 acting through millions of years? Two main results must follow, 

 unless interruptions occur: the lower elevations and the magnificent 

 mountain ranges, which rear their lofty heads above the permanent 

 snow line, will be divided into minor peaks; valleys will be carved 



Fig. 6. — The Delta of the Mississippi. 



out; the whole land surface will slowly waste away, at first rapidly, 

 at last slowly, and be transported to the oceans, where it will form 

 great horizontal beds differing in no essential particular, excepting 

 size, from those shown in Fig. 5 — great deposits that are merely 

 deltas on a large scale. The geologist, however, finds no evidence to 

 indicate that at any time in the earth's history have these theoretical 

 results taken place. Land masses, of continental dimensions, have 

 not been allowed thus to waste entirely away to a general flat- 

 ness on account of the interruptions caused by elevation — the bodily 

 lifting of great areas of rock, even out of the ocean floor, to become 

 mountains or plateaus, in some cases higher than any point in this 

 country. If our observations thus far and those yet to be made serve 

 to make this clear, one of the objects of this article will have been 



