194 Kansas Academy of Science. 



ing actively its southern bank ; perhaps for a time melting 

 tunnels under the ice for some distance. But eventually the 

 ice held undisputed possession and the river was completely 

 dammed, and the water above the ice steadily rose, and we 

 may believe quite rapidly, for the drainage of the whole west- 

 ern edge of the ice contributed to it. 



4. Why the Outlet Was by Paw Paw Creek Rather Than by 

 Pretty Creek. 



Comparing the successive courses of the Kansas, it will be 

 seen that on the whole there has been a steady shifting of the 

 stream toward the south, hence the south side of the old lake 

 basin was considerably further north. This is attested by the 

 absence of bowlders south of the river remote from the ice, 

 except in the old valley of Deep creek. This means that the 

 valley occupied by the railroad, and lower than the old outlet 

 by more than 50 feet, is the work of more recent erosion. A 

 study of the junction of Antelope creek with its tributary 

 from the southeast, near Pavilion station, favors the conclu- 

 sion that the upper portion of Antelope creek formerly be- 

 longed to Pretty creek, and that a divide separated it from the 

 valley of the Kansas. This divide was high enough in the 

 time of Raw Lake to prevent any escape of water except by 

 •the Paw Paw outlet. It should be remembered in this connec- 

 tion that below the limestones, which rise one above another 

 to the west and southwest of the basin, there lies 300 feet of 

 shales, which permit of rapid erosion. 



5. The Filling of the Lake. 



The lacustrine deposits of the lake came mainly from the 

 ice sheet, which both formed the lake and furnished it sedi- 

 ment. When the lake first overflowed and the ice was at its 

 maximum, the latter was probably several hundred feet thick 

 in the river valley. It probably shed small bergs occasionally, 

 carrying debris, including bowlders. Vigorous streams from 

 under the ice doubtless brought much sand and silt. The 

 larger of these. Rock and Camp creeks, brought material from 

 the ice further north. The Big Blue doubtless brought a gen- 

 erous contribution from still further north. The edge of the 

 ice is known to have lain about Blaine some 300 feet higher 

 than the level of the lake ; therefore, there were rapid streams 

 bringing much to the Blue, not only from the northern part of 



