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to s. <br />T.nS <br />07'30" <br />4 i,p OOC <br />FEET <br />r 12S <br />39' 00' <br />T IJS <br /> CAFBFUAN ~••"- <br />,'I <br />' <br />Ya <br />. <br />Yp~: <br />Ys } 1.44 bdfion years <br />Xbc } 1.72 billion years <br /> <br />Xg ~ PRECAMBRIAN X <br />1 >1.71 billion years <br />III IIIIIIIIIIIIIIII <br />DESCRIPTION OF MAP UNRS FOR COLORADO <br />SPRQNGS-CASTLE ROCK <br />(Front Range Urban Cortidor Sheet 3) <br />OP POST-PINEY CREEK AND PINEV CREEK ALLUVIUM (UPPER HOLO- <br />CFSIEI--Gravel, sand, silo and day of stream flood plains and lower terraces not <br />more than 6 m above stream level. Contains pebble lenses N lower part. Deposits in <br />small streams and tributaries are composed of sand, slit and clay. Thkkness generally <br />less than 6 m. Gravelly phases are a source of sound aggregate <br />Oco COLLUVIUM (UPPER HOLOCENE)-Generally unconsolidated material deposited <br />on slopes by gravity and sheetwash. Thickness generally more than 1 5 m. Unit <br />includes talus <br />,~,Qt`~ LANDSLIDE DEPOSITS (HOLOCENE TO MIDDLE? PLEISTOCENE(-Includes <br />slumps, debris flows, earthflows, rockfall avalanche deposits, and similar large masses <br />of I«ally derived debris moved downslope by gravity <br />~~_.Qe5~,: ~~.~ WINDBLOWN SAND (LOWER HOLOCFIJE TO UPPER PLEISTOCENE(-Fine to <br />coarse sand derived mainly from alluvium of major streams and distributed east and <br />southeast of source area by wind <br />'~ju .,a PINEDALE TILL (UPPER PLEISTOCENE)-Gray nonsorted, nonshatifled firmly <br />compacted bouldery sandy till of Pinedale Glaciation on steep east flank of Almagre <br />Mountain near southwest border of map. Thickness about 6 m <br />~: ~.~~ BROADWAY ALLUVIUM (UPPER PLEISTOCENE)-Gravel, sand, silt and clay in <br />stratified alluvial tertace deposits 7.6 to 12.2 m above present stream level. Bouldery <br />cobbly gravel along Fountain Creek and Monument Creek. Sand «curs in drainage <br />courses north of South Platte•Arkansaz River drainage divide and in west-flowing <br />tributaries south of the divide. Commonly less than 7.6 m thick. Source of round <br />aggregate <br />OI LOESS(LOWER HOLOCENE TO UPPER PLEISTOCENE)-Silty material deposited <br />by wind, generally downwind from area of windblown sand: in southeast comer of <br />mapped area <br />"~~Qbt~p ~• BULt L4KE TILL (UPPER PLEISTOCENE(-Gray to yellowish gray unsorted un- <br />stratified firmly compacted bouldery sandy till of Bull Lake Glaciation which forms <br />ridges around Lake Moline. Thickness az much az 30 m <br />Ola .. LOUVIERS ALLUVIUM (UPPER PLEISTOCENEI~tradfied gravel, sand, silt and <br />clay in terraces as much as 21 m above present stream. Bouldery cobbly gravel along <br />Fountain and Monument Creeks. Mostly sand in other drainages. Base of deposit <br />locally az much az 9 m below present stream level. Underlies much of Piney Creek <br />and Broadway Alluviums. Contains some calcium carbonate (CaC031 in upper part <br />and b ironstained in upper 3.7 to 4.5 m. Source of sound aggregate <br />Os SLOCUM ALLUVIUM (PLEISTOCENE)-Bouldery cobble gavel near mountains <br />decreases in grain see away from mountains. Much calcium carbonate ICaCOgI in <br />upper part where no[ removed by erosion, Many unsound stones. Thickness <br />generally less than 7.6 m. Fortes gently sloping surfaces 24 ro 37 m above present <br />streams <br />Ov VERDOS ALLUVIUM iPLEISTOCENE)-Bouldery cobble gravel near mountains <br />decreases in gain size away from mountains. Much calcium carbonate ICaC03) in <br />upper part when not removed by erasion. Contains many weathered stones. <br />Elsewhere deposit lomlly contains bed o(volwnic ash thought to be 600.000 yrs old. <br />Thickness averages about 4.5 m. Forms gently sloping surface 61 [0 76 m above <br />present streams <br />QA' ~ ROCKY FLATS ALLUVIUM (PLEISTOCENE(-Bouldery cobble gravel near <br />mountains: detteases in gain size away from mountains. Much calcium carbonate <br />(CaCO~I in upper part where not removed by erasion. Contains many unsound <br />stones. Commonly about 4.5 m thick Forms gently sloping surlaces about 110 m <br />above present streams <br />~~ NUSSBAUM ALLUVIUM (PLFISTOCENEI-Brownish gray .poorly sorted, firmly <br />compacted, strratlfied bouldery alluvium south of Little Fountain Creek where grovel <br />b composed of granite, porphyry, and gneiss. Brown well-stmtPied, fairly well sorted, <br />weakly compacted coarse sand and pebble grovel between Wr7liams Canyon and <br />Queens Canyon where gravel is composed of tragments of Pikes Peak Granite. <br />Precambrian bio[ite gneiss, and lower Paleozoic sandstone and limestone. Alluvium <br />1.04 billion years <br />PRECAMBRIAN Y <br />