Probable Correlation of Principal Sections of Pre-Cambrian Sediments in Montana and Idaho , by F. C. Calkins. 
Belt mountains 
(Walcott). a 
Cambrian. 
Unconformity — 
Marsh. Shale, red, 
800 feet. 
Helena. Limestone, 
with some shale. 
2,400 feet. 
Lewis and Living- 
ston ranges (Willis).f> 
Top not seen. 
Kintla. Shale, mar- 
oon red; ripple 
marks, etc.; some 
quartzitic and cal- 
careous beds. 800 
feet. 
Sheppard. Quartzite 
yellow, ferruginous 
700 feet. 
Siyeh. limestone, 
dark blue or grey, 
weathering buff, 
with shale inter- 
bedded. 4, 000 feet 
Empire. Shales, green- 
ish grey. 600 feet. 
Spokane. Shales, 
with thin beds of 
sandstone; deep red 
1,500 feet. 
Grinnell. Shale, part- 
ly arenaceous; 
dark red; ripple- 
marked and sun 
cracked. 1,800 feet. 
Grey son. Shales, 
mostly dark grey. 
3,000 feet. 
Appekunny. Shale, 
grey black, and 
greenish , interbed- 
ded with white 
quartzite. 2,000± 
feet. 
Newland Limestone, 
impure, weathering 
buff, with inter- 
bedded shale. 2,200 
feet. Beilina danai. 
Chamberlain. Shale, 
mostly black, with 
some sandstone, 
1,500 feet. 
Altyn. Limestone, 
upper part thin- 
bedded and fer- 
ruginous; lower 
part greyish blue, 
massive, siliceous. 
1,400 feet. Beilina 
danai. 
Base not exposed. 
Philipsburg district 
(Calkins) .c 
Cambrian. 
— Unconformity. — 
Camp Creek. Shale 
and sandstone, the 
latter prevailing in 
upper portion. Col- 
our chiefly red. 
5,000+feet to 0 
feet. 
Newland. Limestone 
thin bedded, more 
or less siliceous 
and ferruginous, 
passing into shale 
generally buff on 
weathered surface 
4,000 feet. 
Mission range 
(Walcott) .d 
Coeur d’Alene district 
(Calkins), e 
Cambrian. 
-Unconformity.— 
Camp Creek. Sand- 
stone, grey, rather 
thin bedded. 1, 762 
feet. 
Upper part of section erod- 
. ed. 
Shales, sandstones, 
and limestones. 
1,560 feet. 
Sandstones, mostly 
reddish. 4,491 feet 
Sandstones, largely 
shaly, colours red 
and grey, with 198 
feet of limestone 
700 feet below top. 
3,887 feet. 
Blackfoot. Limestone 
thin bedded, more 
or less siliceous; 
siliceous layers, 
weathering buff, 
interbedded with 
calcareo - arenace- 
ous shales. 4,805 
feet. Beilina danai 
Striped Peak. Shales and 
sandstone, red and green 
1,000+ feet. 
Cabinet range, western 
and central parts (Calkins). 
Shales and sandstones, med- 
ium to thin bedded; colour 
prevailingly greenish grey, 
but in part red and purple. 
Shales partly calcareous 
and weathering buff. A 
little white crystalline 
limestone, weathering yel- 
low, at several horizons 
Base not seen. 10,000± feet. 
Striped Peak. Shales and 
shaly sandstones, prevail- 
ingly dark red; ripple 
marks, etc. 2,000+ feet. 
Wallace. Shales, more or 
less calcareous, inter- 
bedded with thin layers 
of siliceous and ferrugin- 
ous limestone and calca- 
reous sandstone. Lime- 
stones and calcareous 
shales weather buff. 
4,000 feet. 
Ravalli. Quartzite, 
grey, with some 
dark bluish and 
greenish shale. 
2,000 feet. 
Ravalli. Sandstones, 
quartzitic, fine St. Regis. Shales and 
grained, greyish sandstones, purple and 
purple and grey, green. 1,000 feet. 
2,550 feet. 
Sandstones, compact Revett. White quartzite, 
grey. 1,060 feet. partly sericitic. 1,200 
1 feet. 
Sandstones, green- 
ish grey, finegrain- 
ed, in layers 4 inch- 
es to 2 feet thick. 
4,645 feet. Base 
not seen. Total 
Ravalli, 8,255 feet. 
Neihart. Quartzite, 
with some shale in 
upper part. 700 feet 
Archaean. 
Prichard. Shales, 
dark bluish, inter- 
bedded with sand- 
stone; rusty brown 
on weathered sur- 
face. 5,0Q0± feet. i 
Quartzite, light col-[ 
oured. Base not ex- 
posed. 1,000± feet' 
Burke. Indurated silice- 
ous shales, with sand- 
stones and quartzites, 
prevailingly grey-green. 
2,000 feet. 
Prichard. Argillite, blue- 
grey to black, with dis- 
tinct and regular band' 
ing, interbedded with a 
subordinate amount of 
grey sandstone. Upper- 
most part arenaceous 
and marked with shal- 
low-water features. Base 
notexposed. 8,000+feet. 
Newland. Limestones, thin 
bedded, siliceous and fer- 
ruginous, interbedded with 
more or less calcareous 
shales. 5,000± feet. 
Ravalli. Quartzites, siliceous 
shales, and shaly sand- 
stones; upper part green 
and purple; lower part grey 
mostly greenish, locally 
with faint purple tinge; 
middle part thickest bed- 
ded, and most quartzitic, 
consisting locally of fairly 
pure white quartzite. 8,000 
± feet. 
Prichard formation. Argillite, 
dark bluish, banded. 2,000 
feet. 
Sandstones, grey, thick 
bedded to shaly, inter- 
bedded with more or less 
sandy bluish shales. The 
rocks become more argilla- 
ceous toward the south- 
east. 10,000 ± feet. Base 
not exposed. 
Forty-ninth parallel, between 
crossings of Kootenay 
river (Daly)./ 
Upper part of section eroded. 
Yahk. Quartzite. 500 feet. 
Moyie. Argillite. 3,400 feet. 
Kitchener. Ferruginous 
quartzite. 7,400 feet. 
Creston. Quartzitic sand- 
stones, thick-platy, grey, 
interbedded with a sub- 
ordinate amount of bluish 
argillaceous material . Base 
notexposed. 9,500+ feet. 
oWalcott, C. D. Pre-Cambrian fossiliferous formations: Bull. Geol. Soc. America, vol. 10, 1899, pp. 199-244. 
6Willis, Bailey, Stratigraphy and structure, Lewis and Livingston ranges, Montana: Bull. Geol. Soc. America, Vol. 13, 1902, pp. 305-352. 
c Report in preparation. 
d Walcott, C. D. Algonkian formations of northwestern Montana: Bull. Geol. Soc. America, vol. 17, 1906, pp. 1-28. 
e Ransome, F. L., and Calkins, F. C-, Geology and ore deposits of the Cceur d’Alene district, Idaho: Prof. Paper U. S. Geol. Survey No. 62/1908. 
/Daly, R. A., Summary Rept. Geol. Survey, Canada, for 1904, 1905, pp. 91-100. 
56815— p. 88b. 
