United States Geological Survey YearbookThe Survey, 1987 - Geology |
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Page 6
... million years old ) rocks beneath Lake Huron is critical to understanding the evolution of the Precambrian basement in North America because three major geo- logic provinces intersect beneath the lake . The Precambrian rocks are covered ...
... million years old ) rocks beneath Lake Huron is critical to understanding the evolution of the Precambrian basement in North America because three major geo- logic provinces intersect beneath the lake . The Precambrian rocks are covered ...
Page 7
... flows were folded and tilted . Volcanism ceased , but subsidence of as much as 6 miles continued as a thick , postvolcanic sedimentary sec- tion filled the graben . Ground water accounts for 12 percent ( 144 million gallons. Perspectives 7.
... flows were folded and tilted . Volcanism ceased , but subsidence of as much as 6 miles continued as a thick , postvolcanic sedimentary sec- tion filled the graben . Ground water accounts for 12 percent ( 144 million gallons. Perspectives 7.
Page 8
... million gallons per day ) of all fresh- water withdrawals in Connecticut and sup- plies drinking water to a third of the State's population ( fig . 1 ) . Water is withdrawn through 1,200 community wells ( public supply ) , 3,300 non ...
... million gallons per day ) of all fresh- water withdrawals in Connecticut and sup- plies drinking water to a third of the State's population ( fig . 1 ) . Water is withdrawn through 1,200 community wells ( public supply ) , 3,300 non ...
Page 23
... million met- ric tons of 17.1 percent zinc , 5 percent lead , and 82 grams per metric ton of silver . When production begins in 1990 , Red Dog will be the largest , predominantly base- metal lode mine operating in Alaska . The discovery ...
... million met- ric tons of 17.1 percent zinc , 5 percent lead , and 82 grams per metric ton of silver . When production begins in 1990 , Red Dog will be the largest , predominantly base- metal lode mine operating in Alaska . The discovery ...
Page 25
... million years ) . Hidden beneath these well - known mines may be mineral resources of compa- rable value . The complex Precambrian rocks ( more than 570 million years old ) , which come to the surface in Minnesota and Wisconsin and in ...
... million years ) . Hidden beneath these well - known mines may be mineral resources of compa- rable value . The complex Precambrian rocks ( more than 570 million years old ) , which come to the surface in Minnesota and Wisconsin and in ...
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activities Administration agencies Alaska aquifer basin Bureau Calcasieu River cartographic CD ROM Chief City City of w coal color Commission concentrations Connecticut contamination cooperative Coordination County crater data base Department of Public deposits drilling Earth Science earthquakes energy Enewetak Environmental facilities Federal feet Figure fiscal year 1987 geographic information systems geologic map Geologist geophysical gram graphic ground water hazards hydrologic Hydrologist investigations Lake Nyos land located lower Calcasieu River major Management ment miles million mineral resources mining models National Center National Mapping Division Office organic compounds Park percent Planning processes production projects Province quadrangle Regional Reston rocks samples San Andreas fault San Joaquin River scientific scientists sedimentary sediments seismic selenium Service South Stop studies surface Survey's techniques tion topographic Transportation U.S. Geological Survey United users USGS Vernalis Volcano Water District Water Resources water-use zone