THE PERMIAN SYSTEM IN KANSAS. 37 



sas, the same channel may be alternately canyon and tun- 

 nel, or bridge. 



The best known of these bridges in Kansas is the Nat- 

 ural bridge of Bear creek, south of Sun City. This spans 

 the canyon of the creek, here about 55 feet from wall to 

 wall. The height of the bridge above the bed of the creek 

 is at the highest point 47 feet, at lowest 31, and at middle 

 38. The width of the bridge at middle is 35 feet. The 

 upper surface of the bridge declines toward the down- 

 stream side, but not so much that a wagon drawn by a steady 

 team could not be driven across it. The thickness of the 

 arch is therefore greater on the up-stream side, where it 

 measures 26 feet, than on the down-stream. The relief of 

 the vicinity seems to indicate that at a geologically recent time 

 Bear creek here flowed to the east of its present course and 

 that its waters, becoming partially diverted by an incipient 

 cave, enlarged the latter and finally were wholly stolen by 

 it, the cave at length collapsing save in the portion now 

 constituting the Natural bridge. Nor is it impossible that 

 this piracy may be repeated in a minor way by Sarcophagus 

 cave, which at times already draws a portion of the Bear 

 creek waters to the west of its proper course. 



Reference has been made to a district especially char- 

 acterized by natural bridges of the Medicine Lodge gypsum 

 in Blaine count}^, Oklahoma. For his knowledge of this, the 

 writer is indebted to Mr. Chapman. The district is at the 

 head of Salt creek, a few miles southwest of Okeene and 

 north of Watonga. The bridges are numerous and in some 

 instances are said to be sufficiently large to permit the pass- 

 age of a load of hay beneath them. The scenery in this 

 district is so remarkable that Mr. Chapman states that he is 

 preparing a bill which he hopes to have passed by Con- 

 gress, establishing a "Natural Bridge park" containing 

 about a hundred natural bridges. 



While following down the Cimarron valley to the 

 Great Salt Plain some years ago, the writer discovered 



