.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