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<br />Table 1, Generalized stratigraphic column of the Upper Colorado River Basin study unit <br /> <br />1---. no dais; Fm. formal inn: Ss. sandslone: Grp. gI\lUp: Sh. shall!: Ls. limestone. PlIrenlhescs indil'ale geologic unils 3Ssoc131ed wilh the specilk fonnalioh or <br />(~::rur. Mndified from CashlOn. 197J: Pearl. 1974: Twelo. 1976; 11)79: [980; Tw..::ro and olhers. 197~.J <br />--.) Map <br />c.o <br />...... Period Epoch Stratigraphic unit Princlpallilhology Thickness symbol <br /> (feet) used In <br /> figure 3 <br />Quaternary Holocene and Valley. fill deposits Clay. sand, gravel, boulders, and glacial 20-140 Not <br /> Pleistocene debris mapped <br /> Colluvium,landslide Silt. clay. sand. gra,,'el, and debris piles llHOO Not <br /> debris. glacial moraines. mapped <br /> terrace deposi IS <br />Quale-mar}' Vo 1canic rocks Lava flows. breccias. wtT. and relaled QTuv <br />and Teniary materials <br />Tcniary Miocene and Browns Park Fm Fine.graine-d grayish sandstone. gravel, As Ihick as I,ROO Tu <br /> Oligocene cobbles. cherI. fresh waler limeslone. <br /> and a conglomcrdle at lhe base <br /> Troublesome Fm Chiefly siltslone~ contains beds of volcanic As lhick as 1.500 Tu <br /> ash and somt' sandstone and conglomerate <br /> Eocene Uulla Fm Sandstone and siltstone in {he Piceance As Ihick as 1.000 TI <br /> Basin <br /> Green River Fill Intertonguing lenses of sihstonc. marlstone. As thick as 3.500 TI <br /> sandstone. limestone. and shale <br /> Eocene and Wasatch Fill Clay. shale. aJld lenses of sandstone. 300-5.000 TI <br /> Paleocene limestone. and conglonlcratL' <br />Tertiary and Paleocene and Middle Park Fill Sandstone, shale. conglomerale. and 2.500--5.000 TKI <br />Cretaceous Latc Cretaceous breccia <br /> Volcanic rocks of the Intrusive rocks---rnainly jnlcnnedial~ 10 TKv <br /> Lammide On)geny felsic in composition. some mafic <br />CreltlceOUS Late Mesaverde Grp MudslOne. shale, coal. and varicolored. 1,500-5,300 Kul <br /> (Price River Fm) crossbedded sandsJone <br /> Mancos Sh Dark shale and calcareous shale with As lhick as 4.000 Ku2 <br /> ;nlerbcddC'd sandstone <br /> Pierre Sh Dark shale and sandy shale wilh local 2()(l-4,OOO Ku2 <br /> stringers of sandstone <br /> Colol'3do Grp Calcareous shale and thin.bcddcd limeslone 200-700 Ku2 <br /> (Niobrara Fill and interbedded with shale. dark fissile shale <br /> Benton Sh) with b~nlonific scams. and sandstone <br /> Early Oakola S5. lig.hl-colorcd sandstcme. mostly cross- As thick as 300 KI <br /> Burro Canyon Fro bedded, dark shale. and thin beds of coal <br />Jurassic Latc Morrison f'm Varicolored siltstone and mudslone with 250-600 <br /> (Brushy Basin Mf."mber) beds of sandstone and limestone <br /> Middle Entrada Ss Fine-grained sand'ilOne, mostly crossbcdded 50-200 J <br /> Early Glen Canyon Fm Sandstone. lenses of limestone. varicolored As [hick as 500 li <br /> or Grp. Wingate 5s siltstone. and mudslone <br />Triassic Late Chinle Fm Red siltstone. sandstone. and limestone RO-120 li <br />Permian and Maroon Fm. Belden Fm, Dolomile. limestone. quartzite, s~nds((lne. As thick as 13,000 PIP <br />PelUlsylvanian Eagle Valley Fill conglomerate, shale. and chert <br />Mississippian Leadyille Ls Limestone. dolomite, sandstone. and chen 50-200 MDO <br />Deyonian. Mississippian rocks Dolomite. !ill1eSIOJle, and quar17.ite As thick as 2.500 MOO <br />Ordovician. and including Chaffee Grp <br />Cambrian and Mani!ou Fm <br />Precambrian GTanitc, S(;hist. gneiss. and pegmatite dikes p€ <br /> ENVIRONMENTAL SETTING 5 <br />