12 



GUIDEBOOK OF THE WESTERN UNITED STATES. 



former 



Cutoff 



miles 



1 



one of these abandoned oxbows. At the time the river was agreed 

 upon as the boundary between Iowa and Nebraska Cutoff Lake was 

 a part of its channel, but in 1870 it straightened its course, so that 

 the land partly inclosed by Cutoff Lake, although a part of Iowa, now 

 Hes west of the river and is almost surrounded by territory belonging 

 to the State of Nebraska. This shifting of the river's course can be 

 prevented to some extent by building levees, or embankments. 



embankment 



with 



purpose from Sioux Falls, S. Dak., 160 miles away. The necessity 



some 



Bluffs lies below river level. 



The building of the bridge ^ was regai'ded as a notable feat of engi- 

 ^ering, and its present importance is indicated by the fact that the 



3n railroads passes over it. It spans one of the longest 

 world, the I^Iissouri and Mississippi combined, 3,820 



The bridge crosses this great river 669 miles above the 



traffic of 

 rivers in 

 miles long. 



junction %vith the Mississippi, and the drainage from 323,000 square 

 miles, including large parts of Montana, North Dakota, and South 

 Dakota, passes under it. The water surface has a known range of level 

 of 25 feet at this point; the lowest water recorded was in 1867, and the 



hi 



Omah 



50;000 



second-feet; that is to say, on the average, 50,000 cubic feet (374,000 

 gallons) of water passes under the bridge every second. 



1 The terms right and left as employed 

 throughout tills book apply to the "west- 

 bound journey. 



2 The first bridge built at Council Bluffs 

 was begun by the railroad company in 

 1869 and completed in 1S72 at a cost of 

 $1,750,000. It carried a single tract, con- 

 sisted of 11 spans, each 250 feet long, and 

 was about 60 feet above ordinary flood 

 level, or 50 feet above the highest re- 

 corded level. 



Tlxis heig 



served two 



The river here during low water is 

 about 900 feet wide. Tlie bridge over the 

 main channel rests on five piers, 250 feet 

 apart, that extend to bedrock at a maxi- 

 mum depth of 76 feet below the level of 

 the flood plain. These were built midway 

 bet^veen those of the old bridge. (See 

 diagram on sheet 1, p. IS,) They carry 

 the four main spans, and on each end 

 are three additional deck spans, mak- 



length 



purposes — 



the level of the bluffs west of the river 

 and allowed boats wliich were formerly 



pass 



feet. 



necess 



bridg 



wrecked 



temporary 



until 1886, when it was replaced by the 

 present double-track structure. 



Although the records give no inti- 

 mation of the kind of rock on which the 

 piers rest, it is supposed to consist of 

 limestone and sandstone of Carboniferous 

 (Pennsylvanian) age, which are known 

 from well borings to underlie the glacial 



Omah 



These 



r — 



rocks are exposed in the river bluffs near 



maha 



the train. 



