GEOLOGICAL SURVEY OF THE TERRITORIES. 



73 



sandstone, "which has much 

 Quartzite. Then come one 

 or two rather thick beds of 

 cherty limestone in the 

 beds of shale, and in 

 some instances immense 

 rounded, fiat concretions 

 of cherty limestone several 

 feet in diameter, but not 

 more than 6 or 12 inches 

 thick. So far as I could as- 

 certain, these brown mi- 

 caceous sandstones and 

 shales continue down to 

 the metamorphic rocks. In 

 the interval between the 

 Flat-Head Pass and the 

 Missouri Eiver there are 

 several local anticlinals 

 and synclinals, in which all 

 the series of rocks are ex- 

 posed in their order from 

 the Lower Silurian to the • 

 Cretaceous, inclusive. Here ■£ 

 and there are patches of g 

 igneous rocks which appear > 

 to have produced in soaie s 

 instances these short anti- | 

 clinals. Far up in the val- ° 

 leys of all the little streams ■:^ 

 that flow into the Gallatin ^ 

 Eiver may be seen the mod- > 

 ern deposits, which show > 

 the extent of the old-lake s 

 waters, and as they slowly 

 subsided the present drain- 

 age was marked out. It is 

 by the stripping off of these 

 i^odern beds that the posi- 

 tion of theunderlyingstrata 

 is rendered apparent. In 

 minutely describing the ge- 

 ological features from point 

 to point much repetition 

 is necessary. There is a 

 certain variety in the out- 

 lines of the surface in dilfer- 

 rent localities, even if the 

 geological formations are 

 the same or similar, and 

 the shades of difference 

 strike the eye, but cannot 

 always be expressed clearly 

 in words. In the valleys 

 of all the little streams that 

 flow into the Gallatin from 

 the Gallatin Eange, there is 



the look of basalt or a compact, fine 



a greater or less thickness of the lake-* 



