was laid down, for the most part, in (luict waters; while a large part 

 of the last described, was deposited by running- streams. The latter 

 is overlaid by about two liundred feet of cream colored clays. 

 There is no perceptible break but tlie upper layers are less sandy and 

 are barren of fossils. As will be seen later the fossils show that the 

 lowest bed is White River while the one above the gray marly beds, 

 and probably the last two are Ix»up Fork. 



On top of the benches in many places are hard, brown, rounded 

 rocks, some of them very symmetrical in sliape. In jjlaces tliese 

 form a coarse conglomerate. These rounded stones, which average 

 perhaps three or four inclies in diameter, when the softer material 

 is washed away from beneath, slide down the slopes, in some places 

 forming- a broad river of them, but flowing only when something dis- 

 turbs some part of the mass. The pelibles are composed of hard ma- 

 terial, mostly quartzyte. They are coated brown and the brown color 

 seems, to a slight extent, to penetrate the rock near the surface. If the 

 sun appears when they are wet by a sliower they shine like polished 

 silver. Possibly they were deposited here when the Madison river 

 flowed at this level. 



There is a general similarity in the lake beds where I have ex- 

 amined them yet there are many local differences and a cousideraljle 

 lithological variety; so that in nearly eveiy valley one finds something 

 new and interesting. In one place there are large perpendicular seams 

 of Jasper cutting the hard clay and conglomerate, and cavities coated 

 with hyalite; in another, cavities covered with quartz and caleite cryst' 

 als, the inner ones lined with a thin coat of quartz, and what were ap- 

 parently logs and stumps turned into caleite or with alternating con« 

 centric layers of caleite and quartz crystals. In another place there 

 are what seem to be ancient geyser cones and hot spring deposits, and 

 layers of "petrified moss." On the lower Madison there is much sillc! 

 fied wood some of which is very l>eautiful. There are also small qu8" 

 titles of fossil wood in other localities. 



One almost constant feature of these lake beds is the pure gray 

 volcanic ash occupying one or more layers. On Black Tail Deer 

 creek is a stratum of this material which is seventy or eighty feet in 

 thickness and weathers in a peculiar way. There are pillars standing 

 on the slopes and architectural forms resembling marble temples. 



In many of the valleys the overlying material is incoherent sand 

 and gravel, and this so covers the other beds beneath that there are 

 few good exposures. Then, too, grasses and shrubs cover the slopes 

 and benches thus preventing a study of the strata. 



As stated in the Three Forks Atlas sheet the beds are. in some 

 places capped with basalt. I have not now data sufficient to settle 

 positively the question as to the age of tliese lava flows, whether be- 



