108°W 106°W F Ancestral ron t Rang LARIMER Uinta Sand Upl e ift Little Snake River Wash Ba North Platte River MOFFAT s Yampa River in JACKSON Park-Gore Range Axial ROUTT Ba s in Up li h ft rc as A ek e Dougl Cr White River GRAND 40°N Whi EXPLANATION RIO BLANCO 40°N te Ri Neogene Volcanics ver Upli Neogene Sediments ft Paleogene Volcanics Eagle River Blue River Paleocene-Cretaceous Intrusives Piceance Basin Roaring ForkCentral River Colorado TroughEAGLE Cretaceous Seaway Sediment GARFIELD Eagle River Sawatch Range Aquifers SUMMIT Mesozoic Sediment Aquifers Ancestral Rockies Basins Colorado River Precambrian Basement PITKIN Arkansas River East Muddy Creek Mountainous Region MESA LAKE PARK Unc Mountainous Valleys ompa ghre Up Colorado Plateaus Region lif DELTA t Laramide Basin Outlines Laramide Uplift Axis Uncompaghre Uplift G un Taylor River CHAFFEE nison Laramide Basin Axis GUNNISON Upl Ancestral Rockies Uplift Axis Uncompahgre River South Arkansas River ift Ancestral Rockies Basin Axis Paradox Basin FREMONT MONTROSE San Lui CUSTER s OURAY Up San Miguel River li ft 38°N SAN MIGUEL SAGUACHE 38°N Animas River HINSDALE DOLORES SAN JUAN Rio Grande MINERAL ag Dolores River n S West Dolores River ua J RIO GRANDE ALAMOSA e San MONTEZUMA n Dom Jua Archuleta Anticlinorium San Los Pinos River LA PLATA COSTILLA San Juan Piedra River Basin CONEJOS Tusas Uplift COSTILLA ARCHULETA COSTILLA 108°W 106°W 0 10 20 30 40 50 Miles Geology modified from Tweto (1979); structural features from Hemborg (1996). 0 10 20 30 40 50 Kilometers Figure 12b-01. Mountainous volcanic region. Geology modified from Tweto (1979); structural features from Hembourg (1996). Colorado Geological Survey ON-010 Colorado Groundwater Atlas..