78 



STRUCTURAL GEOLOGY OF NORTH AMERICA 



10 20 3.0 



MILES 



TEMDOr 

 RANGE 



' 



B»e of Btot 



Severol hundred feel of or - 



c Qillaceous rocks In this oreo> 



may be L.-M. Mississippi 



litf.-l P*nnJ 



x k x x x x : 



K/ ' ^ l Ojrj-Dj Jeffenonft Grand View doll. 

 - w.$llurion[ | "" | S| taketown dolomite 



I I On 



M-UCoir.tirioii[ lA\N t f , 

 E3»ou 



Precombnon 



SOturdoy Mountain dol. 

 Kinmhinic quartxitt 

 notheod tandttont to Pilgrim dol. 

 fttlt quarliife 



Llil^jJPBim Pre-Beltion crystalline: rock* 



feet 



1000 



2000 



3000 



4000 



5000 



-$000 



-7000 



-SOOO 



9000 



io.ooq 



Fig. 6.11. Geosyncline, geanticline, and shelf of southwestern Montana and adjacent Idaho. 

 After Scholten, 1957. 



to be Carboniferous. The Carboniferous part of the Stevens series is prob- 

 ably equivalent to part of the Anarchist series on the west and to the Pend 

 Oreille group (Daly, 1912) on the northeast along the 49th parallel. The 

 Pend Oreille is also considered in part Carboniferous. It and equivalents 

 rest on the immensely thick Beltian strata of Proterozoic age which form 

 a north-south belt in northern Idaho, western Montana, and British Co- 

 lumbia east of Kootenay Lake. 



The lower part of the Stevens series was later divided into a number of 

 formations by Park and Cannon ( 1943 ) after Cambrian, Ordovician, and 

 Devonian fossils had been found. Their section is as follows: 



Formation 



Thickness, Feet 



Limestone (Devonian) 



Ledbetter slate (Ordovician) 



Metaline limestone (Middle Cambrian) 



Maitlen phyllite (Lower or Middle Cambrian) 



Gypsy quartzite (Lower or Middle Cambrian) 



Monk formation (Cambrian?) 



Unconformity 

 Leola volcanics (Precambrian) 

 Shedroof conglomerate (precambrian) 



Unconformity 

 Priest River group (Precambrian) 



700 

 2500 

 3000 



3000 plus 

 5300-8500 

 3800 



5000 plus 

 5000 plus 



The Cambrian formations of Park and Cannon have been traced to 

 northeastern Stevens County by Campbell (1947), where diagnostic 

 early Middle Cambrian fossils were found. 



Cache Creek Sequence of British Columbia. Upper Permian sediments 

 are widespread and very thick over much of British Columbia ( Fig. 6.8 ) . 

 A number of formations and groups have been collected under the gen- 

 eral term Cache Creek sequence by White ( 1959 ) . Cherts are very abun- 

 dant in several forms, as well as interbedded andesite and basalt flows 

 and related pyroclastics. Limestone units range from thin intercalated 

 laminae to massive beds thousands of feet thick. In places the Cache 

 Creek beds have been involved in sharp folding and metamorphism, in- 

 cident to later orogenies, but where their relations to older beds have 



; i 



