BULLETIN 611 SHEET No. 18 
MONTANA 
i 
Scale 500,000 
Approximately 8 miles to | inch 
5 \ 
ff ae 113° 112° me 0° ea ae i 2 15 20Miles 
os i A. - An ie . - rt ‘ mY - rt “ 5 
pip me ce _. lL CANADA | ad] lometers 
Ms ERE | ote eo el a 
! 
< ‘ 
— Contour interval 200 feet 
. %, \ ELEVATIONS IN FEET ABOVE MEAN SEA LEVEL MHelmville 
oie \ ) The dist from St. Paul. Minnesota h 10 mi 
. 2 \ The crossties on the railroads are spaced | mile apart 
~ s ; 
o 
Kalispell - # 
| Great Falls ike Lae vot 
Le 7 See Ss i 
es A WO 
7 & o 47 Q Za 
4 SS 
>. o@ ; 3 
. 77) - v 
' oo PS 
2 
j mf 
t : on hale 
46 48] es X / 
a a 
pe as pe 
> EXPLANATION 
y Z 
eZ i A Stream deposits (alluvium) 
Z, 2 1 alluvium 
AZ ee ae 
B_ Clay, voleanic ash, and sand (lake beds) 
158 C_ Shale and sandstone (Colorado formation) 
eS D Red shale and sandstone (Kootenai formation) 1,500 Lower Cretaceous 
mpure limestone and quartzite ( se 
ormation) 430 Jurassic 
Le j 
™~ LLOWwS & 
~~ re : Sandstone and impure limestone (Quadrant 
\ Susp ¢ 23 INATL PARK H formation) 800} Carboniferous 
‘oe oe oo \| Massive blue limestone (Madison) 1,000 
et wna er Lan I | K Limestone and shale 2,700 oo wonian 
: — Ti ead se L_ Red sandstone and shale (Spokane oy 
- formation of the Belt series) 3,000 Algonkian 
e MAP OF WESTERN MONTANA, SHOWING DISTRIBUTION OF KNOWN TERTIARY LAKE BEDS 
THESE TE THE FORMER PRESENCE OF MANY SMALL LAKES OR A FEW LARGE LAKES WITH NUMERC ‘poe ; 
BRANCHES EXTENDING INTO THE MOUNTAIN VALLEYS Q va flows,. basa t 
R_ Lava flows, rhyolite 
S Granite, intrusi 
T Lava flows, andesit d dacit > 
Diorite, intrusive Ry 
0 
at 
z iy 
Xi 
- 13°30 
‘moar sod 
ENGRAVED AMD PRINTED Sy THE US aEmLOciCcA. SURVEY 
