D U D D U D D U U D D D D D D D D D D D D D D D D U U U U U U U U U U U U U U U D D D D U U U U D U U D D D D D D D D D D D D D D D D D D U U U U U U U U U U U U U U U U U U D D D D D D D D D D D D D U U U U U U U U U U U U D U D D D D U U U U U U D D D D D U U U U D D D D U U U U D U U D U D U D D U U U U UD D D D U U D D D U U D U D U D U D U D U D D U U D U D U D Qe Qe Qe Qe Qe Qpp Qb Qe Qb Qe Qs Xq Qe Xq Xk Qs Xk Qb Qe Xq Xq Qpc Qe Xq Qb Qs Qpp Ysp Qb Qb Qc Xq Qb Qb Xq Kptz Qv Qe Qe Qs Xa Ply Kptz Qb Ysp Qb Xbc Qlo Xk Qe Qc Qb Kptz Kpu Kpu Qe Xbc Ply Qpp Qc Xk Qpp Qpc P f Qpc Qc Qc Qe Xk Qe Ysp Ysp YXp Ply Qe Xa Qe Qc Qpc Qe Qv Qc Xbc Qpc Xq Kpl Kl Qpc Xbc Qs Xq Qc Kd Xk Xq Qlo Qs Xq Xk Qpc Kd Xbc Psi Qb Xb Qe Xq Qc Kptz Qe Qpc Kfh Qs Xt Qpc Qb Psi Xt Kptz Qs Kpu Qc Qpc Qc Qb Qs Qe Qlo Ply Qs Qs Qpc Kn Qe P f Qc Qc P f Ysp Kpu Qc Qc Xa Qs Qc Xq Qpc Qc Qc Qs Kd Qe Qlo Xt Kpu Kfh Qs Xq Qc Qpc Qc Qs Qb Qc Kd Xa Kpu Kd Qv Qv Qpp Ysp Qv Qpc Qc Xq Qpc Xb Qc Psi Xq Xq Xt Kn Kfh Qpc Xbc Kfh P f Qb Xk Xt Kprl Qpc Xbc YXp Kpm Ql Qb Qb Xb Kl Xt Kd Psi Xk Qpc Ql Qs Qpc P f Xa Qpc Qc YXp Qc Xbc Xq Kpu Qs Xbc Qc Qpc P f Qlo Kptz Xq Kd P f Xq Qv Xbc Kpm Kpm Qb Qc Kprl Xq Qs Pi Qpc Kd Qpp Xk Qpc Qc Qs Qe Xt Xk TKda Kpl Pl Qlo Qs Psi J mj Xq Xq Qpc Qc Qe Xq Qb Qv Kd Qc Qs Xt Ql Qc Kl Xbc Xb Kpu P f Qpc Xt Xt Qc Xk Kd Ysp Xq Kfh Qs P f Qc Kn Kpl Xa Ply Kptz Qb Ply Qc Qc Xq Xq Ql Qv Kptz Xt Qs Qb Kl Qpp Qs Qpc Qc Qc Qpc Qc Qpc Kn Qb Qs Kptz Qc Kptz Xq Qpc Psi Xb Kfh Ql Qb Ysp Qc Pi Qc P f Xq Ply Xt Qb Kptz P f Kpu Qb Qs Psi Kpm Qpp Qv Qpc P f Xt Xk Psi Ply Pl Kprl Xq Xbc Kpl Kpu Qc YXp Qs Qpp Pi Kptz Kd Ysp Qc Kptz Kd Qpc Qpc Qs Qc Kpu Qc Qc Qc Kl Xq Qs Xq Psi Kpu P f Qpc Qv Ql Kpl Psi Qpc Xk Qpc Qc Kptz Xt Xt Qs Ql Ysp Kl P f Xk Qc Kpu Qs Xb P f Kn P f Kcg Kpl Qe Qpc YXp Ql Qlo Kph Kptz Qlo Ply Kpl Kn Kpl Xt Qb Kfh Kprl Xq Psi Qe Xk Ql Xk Kd Kph Ply Qc Qe Xt Qv Kpm Kpl Xq Qc Qe Ysp P f Xt Ysp Qc Qc Qpc Qprf J mj Qpc Qc Qv Kpu Qc Qc Qc Kl Kpm Qv Qs Kptz Qc Qrf Xq Kn P f Kpl Qc Pl Kn Ql Qe Ysp Qe Xk Qlo Psi Qc Qpc Kph Kpu J mj Qc Qc P f Pi Kn P f Kptz Kpl TKda Pi Tb Pi Kn Qpc Tb Xt Xq Ply Qs J mj Qpp Kpl Kpu Xk Qpc Kfh Kptz Qc Qs Qpc Kd Qpp P f Kd Qe Qpc J mj Pl Qc Kcg Ysp Qc Xa Xbc Qpp Qc Ply Qpc Qc Xt Kpu Qlo P f Qpc Qc Qc Kpl Qc Kd Xa Qs Ply Ply Qlo Qc Psi Xb Xq Kl Ql Qpc Kpu Psi Qpc Kn Qc Kn Kpu Kn Ql Qpc Qv Qc Psi J mj Kl Qc Pi Qc Xa Kpl Qc Qb Qc Kpl Kpm Qs Qc Kpl Qc Qv Qb YXp Kpm Pl Tb Xk Ply Qpc Qb Kl Qc Qpc Kpl Pl Qc Qb Kph Kpu Qpc Qlo Qc Kl Xt TKda Qpc Qv Kn Ti Kfh Kpu Qlo Kpl Qpc Xq Kptz Qs Qpc Qv Psi Kpu Kpl Kpm Qc Qpc Xq Qc Qe Qc Ysp J mj Ysp Pi Qc Qc Psi Qpc J mj Pl Qpc Ql Qe Qpp Kpl Qc Qc J mj TKda Kpm YXp Kptz Qe Xbc Kd TKda Qs Qpc Xt Qs Kn Qpc Kpu Qe Qc Qpc Ysp Kd Qc Qpc Qpc Kpl Kpu Qpp Kd Ysp Kn J mj Qpc P f Qe P f Qe P f Qs Xb Pl Qpc Qb Ti Kpm P f TKda Qlo Xt Kpm Qc Xk Kpu Qpc Ql Qs Kcg Qc Qc Qc Qc Xa Qpc Qv J mj Kpl Qc Qs Qb Qs Pi Ql TKda Qs Kd Qc Qc Kpu P f Ysp Kph Qlo Kpm Kptz Kptz Kptz Kpu P f Qc Kpl Kpm Qc Kfh Kptz P f Kpu Qpc Qpc Kpm Qpc Qpc Qv Qpc Xb Ti Qv Psi Ply Kph Qc Xa Xbc Qv Qc Qc Xq Ply Qs Qb Qpc Qe Qe Qs Qc Kptz Xa Psi Qrf Kd Kcg Qv Xq Qc Qc Kn Qc Xt Qv Qpp Qs Qrf Qc Qlo Kd Kpl Qpc Qc Qs TKda Xa Qs J mj Xt Qpc Kfh Qpp Qpp Qc Qs Xb P f Qc Ply P f Qlo Qv Pl Qpc Kpl Kfh Pl Kpl Qs Kcg Qc Qpc Kl Xt Kph Kpu Kd P f Kpu J mj Ql Kfh Qpc Qe Ql Qs Xt J mj Qc Pl Qs Kprl Kpu Kd YXp Qv Kpu Pl Qpc Qpc Kd Ysp Kn Kl Kfh J mj Xt af Qpc Kpu Kpu Xa Qrf Kd Ply Kpu Kpu YXp Psi Qs Kl Qs Qc Qpc Ql Kpl Qpc Qc Kd Qpc Qc Ply Qc Qs Qpc Qpc Pi Kfh Xa Qv Qc J mj Qc Qc Qc Qc Qv Qe Qs Qc Qc Qc Qs Psi Kfh Kl Kd Kpl Ti Qc Qc Qc Tb Kpu Qc Ply Kpu af Kd Xt Qc Qc Qc Qc Xk Qe Pi Kcg Qs TKda P f P f Ti Qv Pl Ply Qc Qc Qc Ply Qe YXp Qpp Kpl Qv Ql Qpc Qs Kcg Qt Kpm Kpu Qc Kpu Qc Qc Kpl J mj Kcg Kd Qc Kptz Kcg Pl Kpl Kd Qv Ysp Qs Qe Qc Kpl J mj Qc Qc Qe Kpl Qpc Xq Qpp Qc Qlo Kprl J mj Qs P f Pl Qc Ysp Kprl Qv Qc Qs Pi Kpl Qc Pl Kpu Qc P f Qpc P f Qb Pi Qs Kn Qlo J mj Kcg Ysp Qpc Psi Qpc Qs Qc Kcg Kpl P f Qv Qc Xt Kptz TKda Kpl Pl YXp Qc Xb Qb af Psi Xq P f Ql Kptz Pl Qpc Qc Qv Qc Kpu Xa Qc Qc Qc Qb Qv Kd Kpm J mj Qpc Qb Xt TKda Qe Kcg J mj Qc Qc P f Qc Kd Qpc Qpc Qpc Qc Kcg Kph Qpc Qc Kph Xq Pl Qs Qc Qc Qc TKda Qc Kfh Kn Qc Kfh Qrf Kd Kcg Qs Qv Xk Kcg P f Qc Qc Xk Qc Qc Qc Kpm Qb Kpu Kn YXp Ql Qc Qb Qc af Kpl Kpl Qs Qs Ply Kcg Psi Qpc Kph Pi Qlo Kcg Qc Kfh Qs Xb Xa Qc Qv Ply Ply Qc Qc Qv Qc Pl Qc Xt J mj Kcg Qe Qc Psi Xt Xt Kcg Qv Psi Qc Qc Xb Qc Kptz Qv Qc Kpl Kl Kpl Qc Qc Kpl Ply Qpc Qc Qlo Qc Qpp Ql Kcg Kcg Qc Pl Qv Qc Qc af Kpu Ql Qc Qs Ql Qpc Kn P f Qs Xk Qc Qc Pl Xt Qc P f Qpc Qc Qs Qb Kfh af Qc Qc Qpc Kfh Kpl Qc J mj Qc Xb Kpl Ply YXp Qc Qc Qc Ply Qc Qt Qb Qv Kpm Xa Kpl af Qc Qc Qpc TKda Qrf Kl Qc Qc Qc Xk Kptz Qc Kcg Tb Qc YXp Kprl Qc Kptz Qpp Qe Kcg Qc Kpl Kpu Qs Ply Qpc Qv Qc Qc Qs Kfh Qc Xk Qe Kd Qe Ql Xa Qpp Qc Qpc Kpu Qv Kph Qv Qc Qc Kpm Ti Ti Qt Kfh Kpm Pl Qc Qc Ti Kpu Xt Qe Qc Kpu Qpp Qc Kn Qv Qc Qc Qc Kfh Qc Ql Kpl Kl Qpc Kcg af Qc Qc Qpc Qc Qs Kpl Ysp Kcg TKda Kpu Qc Qc P f Qc Ql Kcg Qv Pi Tqm Kn Kd Qc Qc Qc Qpc Ti Qpc Qc Qc Kpm Ql Qs Ti Ql Qc Kpl Qv Xt Qc Kn Xa Qc Qc Qpc Kcg Kpl Ql Kcg Qs Qs Qpc Qc Qc Qt Kcg Qc Kl Kcg Kcg Kfh Qc Qc Qc Qc Qc Xb Qc Ql af Qc Xa Kph Qc Xb Qc Kph Qs Pl Ql Kn Kpu Kpu P f Pl Qc Kptz Kpu Ti Qc Qs Pl Qpc P f Kptz Qc J mj Kfh Kn Qc Kcg Kpl Qs Qc Xb Kptz Qs Qc af YXp Kn Qs Xk Qpc Kptz Qc Qs Qv Qc Xa Qc Kpm Xk Kcg Qc Kptz Kn Qpc Qc Qc Pi TKda Qc Qs Qc Qc Kfh Qv Qv Kfh Qc Qv Kprl Kprl Kptz Psi Kph Ti Qv Qpc Qc Kpm P f Qc Qc Qpc Qpc P f Kn Pl Pi Qc P f Qc Qc Ql Ply Qc Qpc Xq Kptz Pl Qs Qc Qrf Kpu Qt Kcg Qc Qc Xq Qpp Qpc Pl Kn Qs Kph Qc Kpm Qc Qc Qc Qpc Qpc Qc Kpl Qpc Kfh Qc Qv Qc Ysp P f Qc Qv Pl Qc Kprl Xt Kn Kpm Qc Qc Kpm Qc Kptz Kpl Kcg Qs Kcg Qc Qc J mj Qlo Qc Kcg Xt af Qc af Qc af Kl Kcg Kcg Kpl Qs Qb Qc Qpc Kn Qv Qc Psi Qc Qv Qc P f Kpl Qc Qc Kpl Kpu Qc Qpc Qc Kcg Kph Kptz Tqm Qrf Qc Kfh Pl Kcg Pl Kpl J mj Kfh Kpu Qs Kfh Qpp Qc Qc Kfh Qpc Qc Pl Kfh Qc Kfh Qc Qlo Qc Kptz Qc Qc Qc Pl Qc Qs Qc Qb Kprl J mj Kn Qc Qc Kprl Tb af Ti Psi Kph Qc Qpc Qc Qv Qs Kph Qc Qpc Kcg Qc J mj Qpc Qc Kfh Qc Kn af Kprl Pl Qpc Ti Qv Kptz Kph Pl Qv Qe Pl Kpm J mj Qc Qc TKda Qrf Kn Kptz Kd Kptz Kpm Qc Kpm Qs Ql Qc Kcg Qpc Pl Qc J mj Kn Pl Kpu Ply Kl Qc Kprl Qc Qc Kn Kph Qc Qc Qrf Kptz Kph Kpl Kl Ply Kcg Kpu Kn Qprf J mj Kn Kcg Qc Ti Qprf J mj Xb P f Qrf Kptz Kcg Qc Qe J mj Qe Kpm Qs Pi Kprl Qc Kcg Kcg Qv P f Qc Qv Qpp Qs Qpc Ql Qv Qs Qs Kn Psi Kcg P f Qc Qc Ysp YXp Qc Kpu Kptz Qrf Kph Qc Kl Qv P f Pi P f TKda Pl P f Tqm Kpl P f Qv Kn Qv Ply P f Kpm Qrf Qpp Qv Qs Kprl Pl Qc Qprf P f Kcg P f Qpc Xbc Pl Qs Qpp Kl Kcg Ply Kpl Kn Kprl Kl Qprf Qc ARTIFICIAL FILL POST-PINEY CREEK ALLUVIUM (UPPER HOLOCENE) TALUS (UPPER HOLOCENE TO PLEISTOCENE) COLLUVIUM (UPPER HOLOCENE TO PLEISTOCENE) EOLIUM (WINDBLOWN CLAY, SILT (LOESS), SAND, AND GRANULES) (UPPER HOLOCENE TO BULL LAKE GLACIATION) LANDSLIDE DEPOSITS (HOLOCENE TO PLEISTOCENE) PINEY CREEK ALLUVIUM (UPPER HOLOCENE) BROADWAY ALLUVIUM (PINEDALE GLACIATION, PLEISTOCENE) LOUVIERS ALLUVIUM (BULL LAKE GLACIATION, PLEISTOCENE) SLOCUM ALLUVIUM (SANGAMON INTERGLACIATION OR ILLINOIAN GLACIATION, PLEISTOCENE) VERDOS ALLUVIUM (YARMOUTH INTERGLACIATION OR KANSAN GLACIATION, PLEISTOCENE) ROCKY FLATS ALLUVIUM (AFTONIAN INTERGLACIATION OR NEBRASKAN GLACIATION, PLEISTOCENE) PRE-ROCKY FLATS ALLUVIUM (NEBRASKAN(?) GLACIATION, PLEISTOCENE) BOULDER DEPOSITS (PLIOCENE?) QUARTZ MONZONITE (EOCENE) RHYODACITE AND BASALT (PALEOCENE) DENVER (PALEOCENE AND UPPER CRETACEOUS) AND ARAPAHOE (UPPER CRETACEOUS) FORMATIONS LARAMIE FORMATION (UPPER CRETACEOUS) FOX HILLS SANDSTONE (UPPER CRETACEOUS) PIERRE SHALE, UNDIFFERENTIATED (UPPER CRETACEOUS) Upper transition member Upper shale member Richard Sandstone Member, unnamed shale member, Larimer Sandstone Member, unnamed shale member, and Rocky Ridge Sandstone Member. Middle shale member Hygiene Sandstone Member Lower shale member NIOBRARA FORMATION (UPPER CRETACEOUS) CARLILE SHALE, GREENHORN LIMESTONE AND GRANEROS SHALE DAKOTA GROUP (LOWER CRETACEOUS) MORRISON, CANYON SPRINGS MEMBER OF SUNDANCE AND JELM FORMATIONS LYKINS FORMATION (TRIASSIC AND PERMIAN) LYONS SANDSTONE (PERMIAN) SATANKA AND INGLESIDE FORMATIONS (PERMIAN) INGLESIDE FORMATION FOUNTAIN FORMATION (PERMIAN AND PENNSYLVANIAN) SILVER PLUME QUARTZ MONZONITE (PRECAMBRIAN Y) PEGMATITE (PRECAMBRIAN Y OR X) BOULDER CREEK GRANODIORITE (PRECAMBRIAN X) TONALITE (PRECAMBRIAN X) METASEDIMENTARY ROCKS (PRECAMBRIAN X) Quartzofeldspathic schist and gneiss interbedded with mica schist and gneiss Knotted mica schist Porphyroblastic biotite schist AMPHIBOLITE (PRECAMBRIAN X) CONTACT FAULT OR LINEAR FEATURE INFERRED TO BE A FAULT—Dotted where concealed U, upthrown side; D, downthrown side; crosshatched area is brecciated rock D U af Qpp Qt Qpc Qb Qlo Qs Qv Qrf Qprf Tb Tqm Ti Qc Ql Qe DESCRIPTION OF MAP UNITS TKda Kl Kfh Kptz Kpu Kprl Kpm Kph Kpl Kn Kcg Kd JT Rmj T RPl Ply Psi Pi Ysp YXp Xbc Xt Xq Xk Xb Xa P f MISCELLANEOUS INVESTIGATIONS SERIES I–855–G Version 1.1 U.S DEPARTMENT OF THE INTERIOR U.S. GEOLOGICAL SURVEY GEOLOGIC MAP OF THE BOULDER—FORT COLLINS—GREELEY AREA, COLORADO By Roger B. Colton CONTOUR INTERVAL 50 METERS NATIONAL GEODETIC VERTICAL DATUM OF 1929 2002 MAGNETIC DECLINATION AT CENTER OF SHEET TRUE NORTH MAGNETIC NORTH 10° 1 10 KILOMETERS 0 1 2 4 3 5 6 7 8 9 SCALE 1: 100 000 1 8 MILES 1 0 2 3 4 5 6 7 COLORADO MAP LOCATION Universal Transverse Mercator projection, zone 13, 1927 North American Datum Geology compiled in 1976; GIS database by Theodore R. Brandt, David W. Moore, and Kyle E. Murray; Digital Cartography by Theodore R. Brandt; Edited by Alex J. Donatich 105°22'30" 105°22'30" 105°15' 105°15' 105°7'30" 105°7'30" 105°0' 105°0' 104°52'30" 104°52'30" 104°45' 104°45' 104°37'30" 104°37'30" 40°0' 40°0' 40°7'30" 40°7'30" 40°15' 40°15' 40°22'30" 40°22'30" 40°30' 40°30' 40°37'30" 40°37'30" Horsetooth Reservoir Boedecker Lake Welch Res Lonetree Res Lake Loveland Horseshoe Lake Boyd Lake Fossil Creek Res Timnath Lake Windsor Res Lower Latham Reservoir River Platte South Carter Lake Reservoir McIntosh Lake Terry Lake Ish Res Calkins Lake Panama Res No 1 Boulder Reservoir Valmont Res Milton Reservoir South Platte River