Douglass : A Geological Reconnaissance, 263 



if the land at the foot of the mountains had fallen down, perhaps twenty- 

 five feet or more. As I descended the valley I saw it in several places 

 down to near the northern end of the valley, a distance of nearly fifty 

 miles. It is always near the foot of the steep slopes of the mountains 

 near where the Tertiary and recent deposits composing the benches 

 abut against the older rocks. The people in the valley have noticed 

 this phenomenon, and say that it can be traced all along the foot of the 

 mountains to Jack Creek. Both igneous rocks and Tertiary and more 

 recent deposits form the large benches and terraces of the Upper Mad- 

 ison Valley (Plate XIX), which are beautifully developed. These and 

 the older rocks, which occupy higher altitudes, are sometimes locally 

 covered by glacial drift. As in many of the other valleys, both 

 Oligocene and Miocene deposits occur, but the outcrops are few and 

 are limited in extent. 



Arriving in the Lower Madison Valley, I returned the team to its 

 owner, Mr. De Foe Merriman, and returned by rail to the Ruby 

 Valley. 



The Deer Lodge, Bitter Root, and Flathead Valleys. 



From the Lower Ruby Valley my wife and I took the train for 

 Bitter Root Valley and the Flathead Indian reservation, stopping at 

 Deer Lodge, from which, in company with Prof. Percy Perviance, we 

 made several geological excursions. 



East of Deer Lodge the mountains, so far as we examined them, 

 are composed principally of igneous (basaltic) rocks, but I was sur- 

 prised to find Oligocene deposits extending so high on their sides 

 (probably to an altitude of 6,000 feet or more); though farther south 

 they are found as high as 7,000 or 8,000 feet. West of the town we 

 found distinguishable mammalian fossils in both White River (Oligo- 

 cene) and later Miocene beds. 



One day we crossed to the west side of the Deer Lodge River and 

 followed the bench northward to near Pioneer. This bench is com- 

 posed principally of Tertiary deposits, and it slopes eastward from the 

 Powell Mountains* toward the river. On the surface in several places, 

 apparently unaccompanied by any other signs of glacial action, were 

 large granite boulders. Farther north we crossed the moraine of an 

 old glacier which extends from high up in the rugged mountains nearly 



* I have not been able to find that the mountain range west of the Deer Lodge 

 valley has a name, so call it Powell Range after its most prominent peak. 



