BULLETIN NO. 250 PL. IV 
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^ 
GEOLOGIC RECONNAISSANCE 
MAP OF THE 
^ COOK INUET petroleum fields 
SURVEYED WITH TRAVERSE PLANE TABLE 
BY &.C.MARTIN. 
Scale 
LEGEND 
PRE-JURASSIC MIDDLE JURASSIC UPPER JURASSIC 
Coarse crystalline Enochkrn formation Nakjiekibrmation 
rocks and mlrusives Dark sh/de with, basal Odefly arkose , tuff, 
Jheludes basalt along cong.lomerate and with andi'sit'.anjSbagaloTTuwate 
the easterly margin and sorae sandstone, and vriOt sorru- bcLsalt and 
-pnobcMy granite fartfier limestone Carries tnuch interbedxLedsriOLle, 
westincazdes some 
basalts of later age 
■A 
Oil derricks 
Trails 
JULIUS BIEN& CO. LITH. 
