2 BULLETIN 183, UNITED STATES NATIONAL MUSEUM 



to the trained observer, the Dissected Till Plains of northwestern 

 Missouri, in a submature to mature stage of erosion, do not differ 

 markedly from immediately adjoining portions of the unglaciated 

 rolling Osage Plains to the south. 



The Missouri is by far the largest stream in the region. Its course 

 along the great bend represents a readjustment of an earlier drainage 

 pattern whereby preglacial streams got around the ice. South of 

 the Nebraska State line, where the river forms the northeastern 

 boundary of Kansas, it has carved out one of the newer segments of 

 its valley. Owing to this geologic youthfulness and to the resistant 

 character of the underlying rock, the stream here pursues an erratic 

 course through a narrow alluvium-filled trough only 2 to 4 miles 

 wide. The picturesque loess-capped bluffs of Carboniferous lime- 

 stones and shales bordering the valley assume a curiously even front 

 below Leavenworth, where the river cuts across hard limestone for- 

 mations. At Kansas City the Missouri enters the old preglacial val- 

 ley of the Kansas Kiver, which it follows eastward to the mouth of the 

 Grand. Throughout this section the valley is generally broader and 

 the bluff lines are less regular. 



The immediate banks of the Missouri, where not formed by the 

 bluffs, are low, sandy, and tree-lined and for some hundreds of yards 

 back from the river's edge are subject to overflow. At Kansas City 

 the valley floor is approximately 745 feet above sea level, with the 

 elevation between bluff lines varying only a few feet. Higher ter- 

 races or second bottoms are generally absent. Before its partial con- 

 finement by extensive dikes, revetments, and piling, the sand-clogged 

 channel changed frequently, cutting across the necks of meanders to 

 leave oxbow lakes, sloughs, and marshes marking its former course. 

 Aftermaths of such shiftings may be seen in our immediate area in 

 Duck, Burns, Browns, and Cooley Lakes. 



The stream itself is 1,000 to 3,000 feet wide and has an average 

 velocity of about 3 miles an hour, though at high stages this may rise 

 to 6 miles. There is a very uniform gradient of slightly over 0.8 

 foot a mile. Two annual floods occur, in April and in June, at which 

 time the adjacent bottoms are submerged. The low-water stage comes 

 late in fall and winter. Between these alternate low and high stages 

 the mean fluctuation of the water surface at Kansas City is very 

 nearly 15 feet. But the extreme recorded differential is much greater 

 than this — 34.6 feet — from which it may be inferred correctly that 

 tremendous floods sometimes sweep the valley. Records show that 

 in 1903 the high-water mark at Quindaro pumping station, in the 

 valley north of Kansas City, Kans., was 752.4 feet, sufficient to spread 

 across the entire bottoms from bluffs to bluffs. With its innumerable 

 tributaries, the Missouri drains a vast territory, and there is no reason 

 to doubt that equally remarkable if economically less devastating 



