TOPOGRAPHY OF ROUTE FROM THE MISSISSIPPI TO THE COLUMBIA. 103 



prairie, extending with little variation of surface to the head of Mouse river, beyond the forty- 

 ninth parallel ; returning from which river to Fort Union, the plateau is found declining to a 

 \vide valley or coulee, connecting almost directly with the Missouri in a southwest direction, offer 

 ing a good chance to turn the coteau in an engineering view, and becoming thus another im 

 portant kty point on the railroad route. 



From the Shayenne to Fort Union a great many particulars are necessarily passed over, as a 

 detailed notice of them would stretch to tediousness: the number of small ponds and marshes 

 (the nurseries of myriads of frops which positively rise in shoals when intruded upon) are almost 

 beyond counting, and could not possibly be represented on a general map; salt marshes and 

 salt-water lakes occur irregularly; around some of the small lakes the air is impregnate with the 

 offensive exhalations from their waters; and, in one instance, a narrow neck but a few yards 

 wide separates a lake of purest fresh water from another which is intensely salt. Further notice 

 of such facts belongs more properly to the province of the mineralogist, and need not be extended 

 in a topographical sketch. 



The Missouri from the Yellowstone to Milk river is a wide and turgid stream, with an ever- 

 shitting channel choked with sand-bars, which are influenced by every storm ; its great volume 

 of water, however, insuring a navigable channel on one side or other. It flows with a very sinuous 

 course through an intervale of variable width, enclosed by the tall bluffs of the plateaux on either 

 side, which sometimes project upon the bank, in some places leaving an intervale of five or six 

 miles; it is generally deeply fringed with the cotton-wood and its congeners, and occasionally a 

 dense underbrush, affording a secure haunt to the fierce grizzly bear; good grazing occurs in spots, 

 but is generally better among the bluffs and coulees than on the plain, where the soil is mostly 

 hard and dusty, affording, it might be supposed, but a scanty sustenance even to the swarms 

 of grasshoppers, which in certain conditions of the atmosphere take wing, and are seen drifting in 

 a darkening cloud for hours before the wind. The bluffs are composed mainly of a soft, half- 

 formed sandstone, which crumbles under a slight pressure, and is washed by the rains into the 

 most fantastic shapes, resembling fortifications and ordinary buildings; one of these near the con 

 fluence of Big Muddy river is well known as the &quot;Cottage Rock.&quot; The sandstone, or rather 

 sand-rock, as it washes away, discovers petrifactions and lignites of a large size, and is sometimes 

 heard falling in large masses with a dull, muffled sound. These are the &quot;Mauvaises Terres,&quot; or 

 Bad Lands of the hunters, which occur at irregular intervals all along the Missouri, and many 

 of its tributaries, and in some places are of great extent. The columnar and grotesque forms 

 which are seen in great numbers in such places, are probably owing to the unequal induration 

 or cohesion of what was the upper stratum of a vast alluvial deposit; the softer parts yielding 

 quickly to the &quot;scooping action of denudation,&quot; while the harder portion of the sand-rock 

 became so many fixed points foundations, as it were for the formation of a column, the structure 

 commencing at the top. A better idea of their appearance cannot be furnished than by giving 

 an extract from a most effective description by Dr. Evans, in Owen s Geological Survey: * 



&quot; To the surrounding country, however, the Mauvaises Terres present the most striking contrast. 

 From the uniform, monotonous open prairie, the traveller suddenly descends one or two hundred 

 feet, into a valley that looks as if it sunk away from the surrounding world, leaving standing all 

 over it thousands of abrupt, irregular, prismatic and columnar masses, frequently capped with 

 irregular pyramids, and stretching up to a height of from one to two hundred feet or more. So 

 thickly are these natural towers studded over the surface of this extraordinary region, that the 

 traveller threads his way through deep, confined labyrinthine passages, not unlike the narrow, 

 irregular streets and lanes of some quaint old town of the European continent. Viewed in the 

 distance, indeed, these rocky piles, in their endless succession, assume the appearance of massive 

 artificial structures, decked out with all the accessories of buttress and turret, arched doorway, 

 and clustered shaft, pinnacle, and finial and tapering spire. One might almost imagine oneself 

 * Report of a Geological Survey of Wisconsin, Iowa, and Minnesota, by D. D. Owen, page 197. 



