Bulletin of the United States Geological Survey--The Rampart Gold Placer Region, Alaska . LEGENDQUATERNARY Alluvim TERTIARY (Kertai formation) CRETACEOUS? Impure sandstone CARBONIFEROUS Peimsylvanian? DEVONIAN Limestones, greenstones, quartzites,recL andblack slates Cherts, slates,and greenstones PRE-DEVONIAN Quartzite-schists, quartz-mi ca schists, painetiferous schists, and crystalline limestone Intrusive granitic andnionzonitic nocks U S. GEOLOGICAL SURVEY BULLETIN NO 280 PL. GEOLOGIC SKETCH MAP OF THS IAMPART REGION, and , 190 APPROXIMATE Si All — — i £=- -38.
Bulletin of the United States Geological Survey--The Rampart Gold Placer Region, Alaska . LEGENDQUATERNARY Alluvim TERTIARY (Kertai formation) CRETACEOUS? Impure sandstone CARBONIFEROUS Peimsylvanian? DEVONIAN Limestones, greenstones, quartzites,recL andblack slates Cherts, slates,and greenstones PRE-DEVONIAN Quartzite-schists, quartz-mi ca schists, painetiferous schists, and crystalline limestone Intrusive granitic andnionzonitic nocks U S. GEOLOGICAL SURVEY BULLETIN NO 280 PL. GEOLOGIC SKETCH MAP OF THS IAMPART REGION, and , 190 APPROXIMATE Si All — — i £=- -38. QUATERNARY ?CRETACEOUS* CARBONIFEROUS PRE-OEV0NIAN THE RAMPART GOLD PLACER REGION, ALASKA. By L. M. Prindle and F. L. Hess. GEOGRAPHY AND GEOLOGY. By L. M. Prindle. ? GENERAL STATEMENT. The Rampart region is in the central part of Alaska, near the intersection of theone hundred and fiftieth meridian and the sixty-fifth parallel. It is in the westernpart of the large area—embracing approximately 40,000 square miles—delimited byYukon and Tanana rivers and by the international boundary, 300 miles to the east, andis located where the distance in a north and south direction between the two riversis hardly 50 miles (PI. I). The Rampart region is one of the four most important gold-producing regions inthis interstream area. The Fortymile, near the boundary, the Birch Creek, and theRampart regions are adjacent to the Yukon at intervals of about 140 miles westwardfrom the boundary. The Fairbanks region, the most recently developed and at thepresent time the most productive, is in Tanan
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