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TABLE 4-1 <br />STRATIGRAPHIC UNITS IN NORTH-CENTRAL AND NORTHWEST COLORADO <br />(After Tweto, 1977) <br />MAXIMUM <br />AGE THICKNESS (ft) <br />Pleistocene 500 <br />Pliocene-Miocene 3,000 <br />Miocene 900 <br />Eocene 1,200 <br />Eocene 3,900 <br />Eocene-Paleocene 5,000 <br />Paleocene 2,000 <br />L. Cretaceous 5,300 <br />L. Cretaceous 6,100 <br />L. Cretaceous 600 <br />E. Cretaceous 6,000 <br />E. Cretaceous 250 <br />E. Cretaceous 225 <br />L. Jurassic 500 <br />M. Jurassic 100 <br />E. Jurassic-L. Triassic 75 <br />L. Triassic 1,200 <br />E. Triassic-Permian 5,000 <br />Permian-Pennsylvanian 100 <br />Permian-Pennsylvanian 15,000 <br />Pennsylvanian Indeterminate <br />Pennsylvanian 6,600 <br />Pennsylvanian 900 <br />Pennsylvanian 75 <br />E. Mississippian 275 <br />Mississippian or Devonian 50 <br />Mississippian or Devonian 175 <br />L. Devonian 100 <br />L. Ordovician 65 <br />M. Ordovician 80 <br />E. Ordovician 250 <br />L. Cambrian 100 <br />L. Cambrian 150 <br />L. Cambrian 300 <br />Precambrian Y - <br />Precambrian X - <br />Precambrian X - <br />FORMATION OF UNIT <br />Lands End and Grand Mesa Formations <br />Browns Park, Troublesome, and Dry Union <br />Formations <br />Basalt (8-24 my.) <br />Uinta Formation <br />Green River Formation <br />Wasatch Formation <br />Fort Union and Middle Park Formations <br />Pierre Shale <br />Mesaverde Group (Formation) <br />Niobrara Formation <br />Mancos Shale <br />Dakota Sandstone <br />Burro Canyon Formation <br />Morrison Formation <br />Entrada Sandstone <br />Navajo Sandstone <br />Chinle Formation <br />State Bridge Formation <br />Weber Sandstone <br />Maroon Formation <br />Eagle Valley Evaporite (Formation) <br />Mintur Formation <br />Belden Formation <br />Molas Formation <br />Leadville Limestone <br />Gilman Sandstone <br />Dyer Dolomite (Formation) <br />Parting Formation <br />Fremont Limestone <br />Harding Sandstone <br />Manitou Dolomite (Formation) <br />Dotsero Formation <br />Peerless Formation <br />Sawatch Quartzite <br />Granitic intrusive rocks (1 ,400 my.) <br />Grantic and mafic intrusive rocks ( 1 ,700 my.) <br />Metasedimentary and metavolcanic rocks (1,750 - 1 <br />,800 my.) <br />Table 4-1. Stratigraphic units in north-central and northwest Colorado. <br />Daub & Associates, Inc. Page 4-12 NSI Mine Plan 2010 Rev. <br />Printed: 7/5/2010 Section 4 Geology