270 



;MIT1IS0XIAX ^[lSCE[.^ANl•:OUS COLLIXTIONS VOL. 64 



Little Belt Mountains, assigned by Weed to the Siluro-Devonian. 

 In the Half Moon Pass locality, however, the writer collected fossils 

 from the limestone, near the top. to he sin-e. hut from a zone similar 

 in every respect to the strata hetwoen that zone and the Mcas^licr 

 limestone. According- to Dr. (iirty. who maiie the identihcalions. this 

 collection contained Pitmatopora sp.. Spirifcr cciitroinitiis. and several 

 species of Fciicstclla, referred by him to the Madison limestone of 

 Mississippian age." 



Summarized, the Big Snowv section is statetl l)v Calvert as follows : 



Age 

 Uncoil formitv. 



Carboniferous. 



UncoiifoDiiitx ? 

 Cambrian 



Uncoiif anility. 

 Algonkian .... 



.5 i 



g; i fRcd and green sli.. reddisli .^s. 

 ■3; ;. Quadrant .... -I and usually Is. as top meni- 

 l ber 



Thick- 

 ness in 

 feet 



1.300 



SJ 



rLs.. 4 mass members with 



I shaly Is. between. . . . . . . ... 1,400 



S- Madison Is.. .1 Ls. thinly bedded 330 



I Ls. chocolate-brown, fetid 



[ odor when struck 200 



r Meagher Is . . . .Ls. conglomeratic, flat pebbles 300 



Wolsev sh Mainly greenish, micaceous 



.■I ' sh..' 750 



Flathead qtzt.. .Coarse ss. with qtz. congl. 



[ layers 75 



Belt series Dark, limv shaU 



(exposed) 300 



C)ne of the interesting features of the above section is the angular 

 unconformity at the base of the Flathead quartzite. The uplift of 

 the axis of the Big Snowy Mountains in pre-Cambrian time had 

 begun and like similar uplifts of Algonkian strata in the Spokane 

 Hills, west of the Big Belt Mountains. Montana, in the Llano area 

 of Central Texas, and the Grand Canyon area, Arizona, had been cut 

 down by erosion before the deposition of the basal beach sand and 

 gravel by the transgressing Cambrian sea. 



