GEOLOGIC HISTORY OF BOULDER AREA SIGHT GUIDEBOOK DONALD SHEILA MURPHY GRAPHICS ERICA EVENTS ROCKS STRATIGRAPHIC COLUMN PRECAMBRIAN TIME MILLION YEARS AGO OLDEST ROCKS PRECAMBRIAN BILLION YEARS BEFORE PRESENT MEASURED THE DECAY RADIOACTIVE CONSIST GRANITIC METAMORPHIC ROCKS MEANS CHEMICAL REACTIONS OLDER PRESENT LAID DOWN SAND ANCIENT DEEPLY BURIED BENEATH YOUNGER METAMORPHIC TRANSFORMATION DEEP IN COMMON WEST QUARTZITE FOOTHILLS MOUNTAINS UPLIFTED FROM BELOW MAGMA FORMING EXPOSED THE SURFACE TECTONIC PREDOMINANT ROCK BOULDER CANYON BOULDER CREEK GRANODIORITE THE WALLS THE CREST WEST SIDE FLAGSTAFF MOUNTAIN PALEOZOIC AT THE BEGINNING PALEOZOIC ERA OCEAN WATER FLOODED ERODED SURFACE LIME MUD PRECIPITATED DEEPER WATERS OCEAN AS IT THE SANDS BURIED STRATA SANDSTONE THE NEXT MILLION YEARS GENTLE PATTERN GRADUAL FLOODING THE SEA DEPOSITION NONE THIS TIME PERIOD THE LAND ABOVE SEA LEVEL THE EARLY THE PENNSYLVANIAN PERIOD MOUNTAIN RANGES PUSHED CENTRAL AND WESTERN RANGES ANCESTRAL ROCKIES EVENT ABOVE WEATHERING CUT FLOODS LOOSE DEBRIS AWAY THE EAST MIXTURE FINE SANDSTONES SHALES MAKE UP THE FOUNTAIN FORMATION DEEP RED COLOR OXIDATION IRON LAYERING STEEPLY RECENT MOUNTAIN SANITAS FOUNTAIN FORMATION PERMIAN PERIOD CREEP CLIMATE VAST AREAS SAND DUNES DEPTHS FEET THIS REGION THE LYONS THE STONE BUILDINGS THE UNIVERSITY OF COLORADO CAMPUS THE PINK COLOR OF CAUSED TRACES IRON OXIDE GRAINS OF SAND RIDGES THE FRONT MESOZOIC THE END PERMIAN TRIASSIC PERIOD MARKED FLAT FLOODPLAINS RIVERS FLOWING SOFT MUDS THICKNESS UNDERLYING LYONS DEPOSITS TODAY BRIGHT RED SILTSTONE HOGBACK THE REMAINDER CONTINUATION UPLIFT JURASSIC PERIOD LATE JURASSIC DESERT ENVIRONMENT WESTERN COLORADO EASTERN THIN EASTERN EDGE FIELD ENTRADA SANDSTONE JURASSIC FLOODPLAIN CONDITIONS MORRISON FORMATION BLUE VOLCANIC ASH SEDIMENTS SWAMPY LOWLANDS EASTWARD HIGHLANDS VOLCANIC THE WEST UTAH HOSPITABLE ABUNDANCE START CRETACEOUS PERIOD RISING SAME TIME MASSIVE INVASION THE CENTRAL THE NORTH LAYING DOWN DEPOSIT BEACH SAND THE DAKOTA THE GROUP MARINE HARD STARK RELIEF ABOVE AND BELOW TO THE NORTH SOUTH RANGE HUNDREDS CRETACEOUS RETREATS EPISODES BEDS ENVIRONMENTS THE DEEP SANDY COAST NAMES THE VARIOUS BENTON PIERRE SHALE FOX HILLS SANDSTONE LARAMIE FORMATION TOTAL GENERALLY CITY OF THE NATIONAL ATMOSPHERIC RESEARCH THE PIERRE FRESH PIERRE SEEN DITCHES AT THE END THE NORTHEAST LEFT BEHIND COALS WITHDRAWAL CENOZOIC LATE CRETACEOUS TERTIARY MOUNTAIN BUILDING THE MOUNTAINS STREAMS INVADED RICH WATERS MAGMAS THE CRACKS AT THIS TIME MIDDLE TERTIARY PERIOD REACHED OUT IN VOLCANIC ERUPTIONS SCATTERED REMAINS LAVA FLOWS TOPS NORTH AND SOUTH TABLE MOUNTAINS FLATIRONS FRONT BENT UPWARD THE PRESENT SITE ACTIVE QUATERNARY THE ROCKIES ATTAINED GREATEST HEIGHT PEAKS LOWERED GRAVEL EXTRACTED BOULDER COUNTY MATERIALS THE ROCK STRIPPED NUMBER PITS WALDEN PONDS EAST HISTORY OF GAVE ROCKIES PERIODS LOOKING TOWARD MESAS REMNANTS EROSIONAL DEVELOPED REGIONAL THE HISTORY OF ERODE TRANSPORT ONTO THE MOUNTAIN HIGHEST HIGHER SHOWING DOWNCUTTING GEOLOGIC HISTORY FLANK MAJOR REST ON SEDIMENTARY INTERVAL THE QUATERNARY PERIOD GLACIATION TIMES THE PAST SHEETS ICE SOUTHWARD THE ARCTIC COVER CANADA NORTHERN UNITED STATES GLACIERS BELOW FOOT LEVEL GLACIAL DEBRIS GEOLOGISTS RECOGNIZE DISTINCT WAY DOWN THE VALLEYS THE CONTINENTAL MELTWATER GLACIAL DEPOSITS FEATURES TOWNS GEOLOGY INFORMATION MINERAL RESOURCES CROSS SECTION GEOLOGIC MAP RETURN INTRODUCTION TO MINING THE BASIN BIBLIOGRAPHY DIAGRAM GEOLOGIC FORMATIONS DISCUSSION GEOLOGIC ERA WATERSHED THEME INVITATION BASIN COMMUNITY PROJECT PUBLIC PARTICIPATION FEEDBACK WELCOME SUGGESTIONS FIND YOU CAN INVOLVED CLICK HERE THE US PROGRAM SITE MAP GLOSSARY ATTRIBUTION SEARCH LAST PAGE UPDATE