FLQiTZ TKAI' FORMATIONS. 205 



part of the stratum has ficquciilly least colour, and is also 

 most compact and hard. Tiiis is not liowevcr invariably 

 the case : for aI)out tlic Platte, tliat part of it which lies im- 

 mediately upon the granite is white, and contains numerous 

 and extensive beds of coarse puddingstone. Al)out the Cana- 

 dian, and in other places wlierc tiiis rock still lies in its original 

 horizontal position, the up|)er part of the stratum is soft, and 

 pretty uniformly of a red or yellowish brown colour. It is 

 disposed in immense horizontal strata or lamina;, which when 

 broken, transversely exhil)it some tendency to separate into 

 fragments of a cubic or rhombic form. In tlie face of the 

 high precipices, are often seen broad stripes or belts of a 

 lighter colour, conspicuously marked with reticular yellow- 

 isli veins, wliich arc of a substance similar to hornstone. 

 The cross fracture of the rock of course varies with the linc- 

 ness of the particles of sand of which it is composed. It is 

 often even, and sometimes approaching to splintery. When 

 divided in a direction parallel to tlie stratilications, it fre- 

 quently exhibits small scales of mica ; but these arc not nu- 

 merous. Specimens from many parts of this stratum are 

 entirely similar to that which is quariicd in New Jersey, 

 and used in great quantities in the cities of New York, Al- 

 bany, ^'c. for building. That (jf the Rocky Mountains usually 

 contains less mica and in smaller scales ; but in other re- 

 spects is similar. The cement of this rock is sometimes 

 argillaceous; but I iK'Iicvc this is iiy no means universal. 

 WJiethcr this sandstone is in all respects similar to the '' Old 

 Red Sandstone" of Werner,* which makes so conspicuous a 

 figure in the systems of certain geologists, we are not able 

 to say. It however certainlv occupies a place similar to the 

 one which has Ijcen assigned to that rock. It is the lowest 

 of the flcetz or horizontally stratified rocks, and it is perhaps 

 not improbable that it may extend under a great part of the 



• This red sanilstoiie is first found on the wafers of the lakes on the strait 

 between Lake Uircm and Lake Superior, anil form- the fall tiillcd the Sautdc 

 St. Marie BoIdw that [.oint of the tide water, it is- gciieially limestone. 

 VOL. II. E 2 



