OBJECTIONS TO THE LACUSTRINE THEORY. 545 



Objections to the Theory. — In considering this theory and the evidence 

 bearing upon it, several embarrassing questions are met. Where are the 

 ancient beaches ? If this sketch is anywhere near the truth, we may 

 well ask where are the beach lines which should have been formed. 

 From the analogy of lake Agassiz we should expect to find gravel 

 beaches, and long spits and loops built out of the chert nodules occur- 

 ring so abundantly along the slopes of the Burlington limestone on the 

 south and east. On the contrary, we find no traces whatever of beach 

 lines, nor do the fragments of chert show traces of wave action. The}^ 

 usuaUy have sharp edges and prominent angles. 



Why should there be no more traces of stratification? Although we 

 may imagine that in some way beaches had been entirely removed, or 

 that few were formed, we should still expect more cases of stratification. 

 The average section of the deposits need not be repeated ; its uniformity 

 is surprising; and while this may not disagree with the lacustrine 

 hypothesis, in the center of the area where the water may have been 

 deep we should still expect to see extensive. areas of unstratified sand 

 and clay near the margins ; but they have not been found. 



How can this theory be reconciled with the deep troughs of the Mis- 

 souri and Mississipi^i ? ^^^e have already suggested in the statement of 

 our theory a way by which we may ease this difficulty until we take it 

 up in connection with the next liead. 



THE FL U VIA TIL E H YPO THESIS. 



The Hypothesis stated. — This hypothesis may perhaps be rendered most 

 probable by stating it somewhat as follows : \Vhether streams were flow- 

 ing at the opening of the Pleistocene epoch at higher relative levels than 

 now or not, we presume that a northeast extension of the Ozark uplift, 

 between the Osage and Gasconade rivers, was intact, and that both 

 flowed northeast into the IlUnois river. The Kansas, possibly receiving 

 the waters of the present Missouri above that point, may have flowed 

 across past Moberl}^ or Macon to meet the Osage. All streams were 

 probably sluggish, except in the western i)art of the state. The mpids 

 at W^eston may liave been forming at this stage, as also deposits of gravel 

 up the Kansas river. As the ice-sheet advanced, probably entering the 

 northern part of the state, these rivei*s were swollen to great volume, and 

 at numerous points icebergs from the glacier's front fell into them. 

 There was probaljly a northward depression of the region which made 

 them still more lacustrine in their character, but did not entirely stop 

 their currents. They deposited the abundant debris which was borne 

 by them very largely in the northern portion of Missouri. In so doing 

 they shifted back and forth until the whole region was covered with 

 bowldery clay. In this work they were probably assisted by the Des 



