Red Rocks Amphitheater, west Denver --- Tilted layers of Fountain Formation are sand and conglomerate deposited from erosion of the ancestral Rocky Mountains. [N39.665º × W105.206º]Colorado
12-23 July 2009
ITINERARY
Numerous sites illustrated geological issues during the field conference in the Rocky Mountains. Many of the following locations were part of the itinerary:
FIELD GUIDES
PICTURES -- CLICK ON ANY PICTURE FOR A LARGER VIEW
This field conference will see some of the following:
Red Rocks Amphitheater, west Denver --- Tilted layers of Fountain Formation are sand and conglomerate deposited from erosion of the ancestral Rocky Mountains. [N39.665º × W105.206º]
Garden of the Gods and Pikes Peak, Colorado Springs --- The red Lyons sandstone layers were uplifted vertically when the Rocky Mountains were uplifted. The 14,000 foot Pikes Peak in the background is a lone Precambrian granite intrusion. [N38.879º × W104.870º]
Limestone cliffs of Williams Canyon, just west of Colorado Springs --- Ordovician to Mississippian limestone forms the canyon cliffs. The limestone was dissolved to form the Cave of the Winds tourist attraction with its entrance seen on the cliff. [N38.868º × W104.920º]
Rift Valley and part of Collegiate Peaks, Buena Vista --- The Rift Valley is formed by plate tectonic processes pulling the continent apart. Mt Princeton,
seen in the right half of the picture, is formed from solidified granitic magma. The granite cooled, solidified, was uplifted and then overlying sediments were eroded off. [N38.816º × W106.087º]
Mt. Sopris, Carbondale --- The granitic magma that solidified to form this mountain was intruded below sedimentary layers that have since been eroded away on top, but still remain tilted upwards along the edges. [N39.436º × W107.249º]
Glenwood Caverns at Glenwood Springs --- The caverns were formed by dissolution of the limestone, The stalagtites were then formed by water dripping from the ceilings of the caverns. [N39.56º × W107.32º]
Rocky Mountain National Park --- The valley has been carved by glaciers between the viewpoint from Trail Ridge Road and the string of peaks in the distance along the Continental Divide. Longs Peak, the only 14,000 foot peak in the park, is the flat-topped mountain in the far distance. [N40.433º × W105.768º]
Layers of Life, Rocky Mountain National Park --- An interpretive sign labels the ecosystems viewed at different elevations from this roadside stop: montaine, subalpine, and alpine. A total of eight different ecosystems can be found in Colorado, each with its own set of plants and animals. [N40.401º × W105.663º]
SEDIMENTARY - CLASTIC: Conglomerate in a recent stream channel deposit, Colorado River Rd near McCoy --- Several features can be observed in the picture: Rounding of the boulders was probably caused by tumbling in a stream channel. Variation between sand layer and boulders indicates a variation in stream energy from low to high. [N39.907º × W106.771º]
SEDIMENTARY - CLASTIC: Conglomerate of the Fountain Formation, Red Rocks Park, west Denver --- These large boulders were rounded and transported by high-energy water action as the ancestral Rockies were eroded. [N39.667º × W105.208º]
SEDIMENTARY - CLASTIC: Sandstone of the Fountain Formation, Red Rocks Park, west Denver --- Vertical height of the picture is about 15 feet. [N39.67º × W105.20º]
SEDIMENTARY - CLASTIC: Shale of the Green River Formation, Rt.139 near Douglas Pass --- Mud settling out of quiet water becomes hardened to form shale. Organic material gives the darker gray color to some of the layers; this oil shale is a mostly untapped energy resource. [N39.60º × W108.81º]
SEDIMENTARY - CHEMICAL: Mississippian Leadville Limestone at Minturn [N39.592º × W106.433º]
SEDIMENTARY - CHEMICAL: Pennsylvanian Eagle Valley evaporites, Rt.82 south of Glenwood Springs --- Gypsum is assumed to have formed in a hot, arid climate by evaporation of sea water in a closed basin causing the precipitation of calcium sulfate. After burial, this soft rock easily flows forming the chevron fold seen in this picture. [N39.444º × W107.256º]
IGNEOUS - INTRUSIVE: Potassium feldspar, Big Thompson Canyon --- The potassium in this pink mineral is often used in K-Ar (potassium-argon) radiometric dating. [N40.409º × W105.395º]
IGNEOUS - EXTRUSIVE: Basalt cliffs, Grand Mesa --- Tertiary basalt flowed down a valley and hardened. Later erosion formed these cliffs where the hard basalt caps the mesa. Grand Mesa is an inverted valley -- what was low has now become high. [N39.056º × W108.068º]
IGNEOUS - EXTRUSIVE: Volcanic tuff layers, Rt.34 near Grand Lake --- This volcanic ash was deposited in the Tertiary. [N40.247º × W105.840º]
METAMORPHIC: Gneiss, Big Thompson Canyon --- In this high-grade metamorphic rock, the lighter colored layers melted and recrystallized between the darker colored layers. [N40.409º × W105.395º]
UPLIFTED: Garden of the Gods, Colorado Springs --- Layers of Lyons sandstone were tilted vertically when the Rocky Mountains were uplifted. [N38.880º × W104.883º]
UPLIFTED: Interstate-70 roadcut, west Denver --- A thick sequence of rock layers tilted upwards as the Rocky Mountains were uplifted. [N39.702º × W105.201º]
UPLIFTED: Turbidite deposit near McCoy --- Deposition is by underwater mudflows. Vertical layers are due to later uplift of hardened rock. [N39.8858º × W106.6987º]
PARACONFORMITY: Hanging Lake area, Glenwood Canyon --- An unconformity occurs between the lower Ordovician Manitou Formation and the upper Devonian Chaffee Group. [The Manitou Fm extends left horizontally from the lone tree on the sloping skyline ridge in the middle of the picture. The formation is about twice as thick as the tree is high. The Chaffee Group is about the same thickness and is the next higher layer with many tree growing along the top of it on the skyline.] The 25 million year-long Silurian period is missing between them, although no evidence is found here for major erosion in the lower layer. [N39.591º × W107.187º]
ANGULAR UNCONFORMITY: Along Interstate-70, New Castle --- Rock layers were deposited, hardened, uplifted at an angle, eroded flat, and then more rock was deposited on top. [N39.572º × W107.482º]
ANGULAR UNCONFORMITY: Along Rooney Rd, west Denver [N39.708º × W105.196º]
Pennsylvanian Minturn Formation near Minturn --- Limestone was deposited as fringing reefs in the middle of the geologic column according to standard interpretation. In the center of this picture, the "reef" forms the layer at the top of the cliff. Calamites tree trunks are preserved in position of growth in this formation suggesting rapid deposition. [N39.57º × W106.40º]
Clastic dike in the Maroon Fm at Vail Pass along Interstate-70 --- The Maroon Fm on the west side of the Ancestral Rockies corresponds to the Fountain Fm on the east side. Both were deposited from the outwash of the erosion of the ancestral Rockies. The sand in the diagonal cross-cutting dike had not yet been turned to stone when it was intruded into a crack in the horizontal sandstone layers. [N39.5268º × W106.2189º]
WATER: Raindrop impressions, Parfet Prehistoric Preserve, Golden (west Denver) [N39.743º × W105.220º]
WATER: Ripple marks, Dinosaur Ridge, west Denver [N39.678º × W105.192º]
WATER: Cross-bedding, Co. Rd. 301 near McCoy --- About one third of the way up the picture are beds at an angle to the main layers. [N39.905º × W106.766º]
WATER: Stream meanders, Horseshoe Park, Rocky Mountain National Park --- Water descending rapidly down a canyon forms a straight path, but when it arrives in an almost level valley it meanders as shown in this picture. The lower Mississippi River shows similar meanders. [N40.40º × W105.62º]
WATER: Dissolution caves in the Mississippian Leadville limestone, Glenwood Canyon, Interstate-70 --- As acidic water dissolved the limestone, caves formed as seen here and sinkholes formed at the upper surface. In the standard interpretation, the ancient sinkhole land surface at the top of this formation formed a karst topography similar to what is seen in some places in Florida today. [N39.552º × W107.317º]
GLACIATION: Glacially U-shaped valley and Longs Peak, Rocky Mountain National Park [N40.27º × W105.64º]
GLACIATION: Moraine Park from Many Parks Curve, Rocky Mountain National Park --- Glaciers moving to the left in the picture along what are now light green meadows pushed boulders to each side into elongated hilly moraines now covered by darker colored trees. [N40.387º × W105.632º]
GLACIATION: Rouche moutonee, Moraine Park, Rocky Mountain National Park --- As glaciers moved to the left in this picture, they would leaves streaks up one side of the rock mound and then pull rocks away from the small cliff face on the left. [N40.35º × W105.60º]
SMALL-SCALE FOLDING: S-folds in banded gneiss, Big Thompson Canyon [N40.409º × W105.395º]
TECTONIC FOLDING: Large fold in gypsum layers, Sweetwater Canyon --- Folding is the result of enormous tectonic forces. [N39.726º × W107.046º]
TECTONIC FOLDING AND FAULTING: Harpers Corner, Dinosaur National Monument, Colorado --- Relative uplift of layers on the right hand side of the picture caused folding of the originally horizontal layers and a vertical fault at the left center. [N40.54º × W108.99º]
TECTONIC FAULTING: Thrust fault along Interstate-70, Silverthorne --- Younger rocks on the very bottom of this picture have been thrust under older rocks and pushed west (left) for several miles. The fault line ascends slowly from the lower right edge of the picture to beyond the center where some folding of the layers at the fault contact can be seen. [N39.635º × W106.052º]
TECTONIC FAULTING: Thrust fault at Wolford Mountain east of Rt.40 north of Kremmling --- Trees take root in the older Precambrian rocks outcropping over the top half of the mountain, but do not grow in the younger Cretaceous Pierre shale outcropping over the lower half. [N40.105º × W106.423º]
ENERGY SOURCES: Uranium roll-front deposit, Turkey Creek, west Denver --- Research has been done as to method and rates of formation. [N39.6350º × W105.1688º]
ENERGY SOURCES: Oil seep and sulfur, Turkey Creek, west Denver [N39.6349º × W105.1690º]
ENERGY SOURCES: Burning Mountain, New Castle --- Burning coal seam heats up the ground so there is a horizontal bare streak across the hill that is too warm for vegetation to grow. [N39.5686º × W107.5175º]
ENERGY SOURCES: Mesa Verde Formation, Rt.139 south of Rangely --- Coal seams in this formation ignite and burn, baking to a bright red, nearby shale and sandstone layers. [N39.7325º × W108.7970º]
MINERAL RESOURCES: Phoenix gold mine, Idaho Springs --- A mineral vein colored blue-green by copper compounds. [N39.749º × W105.565º]
WATER RESOURCES: Dillon Reservoir, along Interstate-70 --- Denver's need for water has resulted in the building of several diversion tunnels bringing water from the west side of the continental divide. The more than 20-mile long tunnel from this reservoir empties into the South Platte River which runs through Denver. [N39.601º × W106.089º]
CATASTROPHE - EARTHQUAKE: National Earthquake Information Center, Golden (west Denver) --- United States Geological Survey center for real-time compilation of the world's earthquakes. [N39.749º × W105.220º]
CATASTROPHE - FLOODING: Lawn Lake flood outwash from Rainbow Curve, Rocky Mountain National Park [N40.410º × W105.635º]
CATASTROPHE - FLOODING: Caution sign, Big Thompson Canyon --- On July 1, 1976 a flash flood killed at least 139 people and destroyed houses, bridges, and the canyon highway. Heavy rains falling in the headwaters of the Big Thompson River moved boulders as large as 20 feet across and caused the river to rise 14 feet in just a few minutes at the canyon's mouth. [N40.433º × W105.338º]
CATASTROPHE - METEOR IMPACT: Colorado's newest meteorites, Denver Museum of Nature and Science --- The Cotopaxi 8.5 ounce nickel-iron meteorite was found by metal detector near Pueblo in October 2000. The Elbert stony (chondritic) meteorite, consisting of two pieces weighting 1.75 and 10 ounces, was recovered after a spectacular fireball in January 1998. [N39.748º × W104.943º]
PALEONTOLOGY (FOSSILS)
Dinosaur trackways, west Denver --- Dinosaur Ridge with trackways in the Dakota sandstone [N39.679º × W105.192º]
Dinosaur bone bed, Jensen, Utah --- Morrison Formation at the Quarry Exhibit Hall, Dinosaur National Monument --- [N40.440º × W109.301º]
Tyrannosaurus rex, Denver Museum of Nature and Science [N39.748º × W104.943º]
Plesiosaur skeleton, Denver Museum of Nature and Science --- A marine lizard with a small head, long neck, and powerful paddles for limbs. [N39.748º × W104.943º]
Ammonite fossils, Denver Museum of Nature and Science --- Fossils of shells related to the still-living chambered nautilus. [N39.748º × W104.943º]
Burrows, Dinosaur Ridge, west Denver --- These tubes are assumed to be traces of animals that formed burrows on the surface of underwater sediment. [N39.678º × W105.192º]
Crinoid stems, Harpers Corner, Colorado --- Dinosaur National Monument [N40.534º × W109.008º]
Upright petrified tree stump, Florissant National Monument [N38.9135º × W105.2860º]
Leaf fossils, Florissant Fossil Quarry --- Rapid burial resulted in exquisite preservation of details in these and other fossils, such as insects. [N38.9435º × W105.2906º]
Fossil palm frond, Parfet Prehistoric Preserve, Golden (west Denver) [N39.743º × W105.220º]
Stromatolite layers, Lykins Formation, Red Rocks Park, west Denver --- These bands are interpreted to have formed as stromatolites, algae mats that catch sediment in concentric layers. [N39.6772º × W105.1986º]