.0 IGNEOUS ROCKS Yp ROCKS OF PIKES PEAK BATHOLITH (1,000-M.Y. AGE GROUP)--Includes Pikes Peak, Mount Rosa, Windy Point, and Redskin Granites and unnamed rocks Yg GRANITIC ROCKS OF 1,400-M.Y. AGE GROUP (AGE 1,350-1,480 M.Y.)--Includes Silver Plume, Sherman, Cripple Creek, St. Kevin, Vernal Mesa, Curecanti, Eolus, and Trimble Granites or Quartz Monzonites; also, San Isabel Granite of Boyer (1962) and unnamed granitic rocks Yam ALKALIC AND MAFIC ROCKS IN SMALL PLUTONS, AND DIABASE AND GABBRO DIKES Xg GRANITIC ROCKS OF 1,700-M.Y. AGE GROUP (AGE 1,650-1,730 M.Y.)--Includes Boulder Creek, Cross Creek, Denny Creek, Kroenke, Browns Pass, Powderhorn, Pitts Meadow, Bakers Bridge, and Tenmile Granites, Quartz Monzonites, or Granodiorites; also, unnamed granitic rocks Xm MAFIC ROCKS OF 1,700-M.Y. AGE GROUP--Gabbro and mafic diorite and monzonite YXg GRANITIC ROCKS OF 1,400- AND 1,700-M.Y. AGE GROUPS, UNDIVIDED, OR, IN TAYLOR RIVER REGION, ROCKS WITH CHARACTERISTICS OF Xg BUT U-Th-Pb ZIRCON AGES OF Yg