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Barr Lake is located where there was a natural depression in the prairie that made a good bison wallow. Barr Lake did not exist until a dam was built and water was diverted from the South Platte River to fill it. Barr Lake is a great place to enjoy an uninterrupted view of the Rockies rising from the plains and to contemplate all the layers of the story underneath. To reach Barr Lake
State Park from Denver, take I-76 north to Bromley Lane. Go east to Piccadilly
Road and drive south to the park entrance. Located east of the Dakota Hogback, Bear Creek flows over tilted Pierre Shale. This Cretaceous marine mud is the bane of Denver homebuilders, especially when the layers dip steeply. Weathered volcanic ash from volcanoes is a common component of the Pierre Shale. The bentonite swells greatly with the addition of water, creating the swelling soils that crack foundations. Also present in this park is the Fox Hills Sandstone and the Laramie Formation. Coal was mined in this area from the Laramie Formation. Bear Creek Lake Park
is located just west of Denver near Morrison, on CO 8. One of the many parks
formed around reservoirs, Chatfield was formed in 1973 by the damming
of the South Platte River just downstream from the Front Range. Just south
of Chatfield lies the Lamb Springs To reach Chatfield
State Park from Denver, go south on Wadsworth Cherry Creek is one of the several reservoirs created to control flooding in Denver. If you walk along Cherry Creek today, you can hardly imagine that this small stream poses any danger. Yet summer thunderstorms in the Denver Basin can unleash deadly torrents. The bedrock beneath the lake and exposed in small bands around the path is the Paleocene portion of the Denver Formation and Dawson Arkose (D1 sequence). Fossil leaves are abundant in this area. To reach Cherry Creek
State Park, go 1 mile south of I-225 on Parker Road and turn west on Lehigh
Avenue. Deer Creek Canyon is cut through the Dakota Hogback and provides good exposure of the Dakota Sandstone. Just north of here, natural petroleum is seeping from an outcrop of the Dakota Sandstone. This layer of sandstone forms a major reservoir of oil and natural gas in the northern reaches of the Denver Basin. To reach Deer Creek
Canyon Park from I-70, travel east on C-470 to Wadsworth. Exit southbound
to South Deer Creek Canyon Road. Turn west and continue to Grizzly Drive
where you'll venture south approximately .25 mile to the parking lot.
Denver is one of
the few cities in the world to have dinosaur bones and dinosaur footprints
nearby. Dinosaur Ridge is definitely the best place to easily see these
kinds of fossils. Dinosaur Ridge has an excellent visitor center, and
Alameda Parkway provides world-class exposures of the Jurassic Morrison
Formation and the Cretaceous Dakota Sandstone. Dinosaur tracks are visible
in both formations, and dinosaur bones are exposed in roadcuts in the
Morrison, on giant stone blocks in the parking lot of the visitor center,
and on Roony Road. Friends of Dinosaur
Ridge Phone: 303-697-DINO
(3466) 7. Golden Gate Canyon State Park Deep within the Front Range, Golden Gate State Park is located on Precambrian crystalline rocks that are at least 1.7 billion years old. To reach Golden Gate
Canyon State Park, take CO 93 north from Golden 1 mile to Golden Gate
Canyon Road. Turn left and continue for 13 miles to the park. 8. Green Mountain This low, rounded mountain is here today because it is capped with and largely made up of coarse, resistant cobbles, part of the D1 sequence of the latest Cretaceous and earliest Tertiary fill of the Denver Basin. This rock texture is called conglomerate. Near the base of the mountain you will see the pebbles are brown and resemble baked potatoes. At the top of the mountain the pebbles are made of granite. Indeed once near the top of the mountain you can find granite cobbles with nary a volcanic pebble in sight. The rock record is telling you that the volcanic rocks that once must have been common in the drainages of the streams bringing rocks into the Denver Basin were completely stripped away and the youngest conglomerates on the mountain were delivered from a terrain without volcanic material. The volcanoes have vanished, washed away entirely by the ancient rivers. 9. I-70 roadcut at the Morrison exit Geologists have a love-hate relationship with road builders. First they make roadcuts and expose the earth, then they blade the roadcuts away and plant grass to cover it up all over again. The I-70 roadcut is a great example of one that was too good to hide. Famous since it was made during construction of the interstate, this awesome cut exposes the multihued Morrison Formation and the Dakota Group. Numerous signs on the north trails on both sides of the interstate interpret the rock layers. To reach the I-70 roadcut from Denver, take I-70 west to the Morrison exit. 10. Ken-Caryl Ranch To reach this community you drive through a gap in the Dakota Hogback. Excellent exposures of the Dakota Sandstone can be seen as you pass through the hogback. Below the tilted Dakota Sandstone, the Morrison Formation is poorly exposed in a grassy slope. The red mudstone and sandstone beds at the base of the slope are part of the Lykins Formation. The swath of white to light gray-brown sandstone cliffs is the Lyons Formation; look for the characteristic large-scale cross bedding, typical of windblown sediments. To the west, within the community, bluffs and resistant patches of the Fountain Formation occur. To reach the Ken-Caryl
Ranch from Denver, take C-470 west to the 11. Morrison Natural History Museum Explore regional
dinosaur history and contemporary natural history hands-on in this museum
housed in an intimate log ranch house. The Museum collections include
some of the dinosaur fossils excavated from several of the inconspicuous
pits in the Jurassic Morrison Formation, which forms beneath the resistant
Cretaceous Dakota Sandstone, in turn forming the crest of the hogback.
Visitors get to help chip rock away from bones of the first Stegosaurus
discovered in the world. Visitors can also compare Archaeopteryx (a
Jurassic bird) replicas and other Bavarian specimens displayed nowhere
else, and get To reach the Morrison
Natural History Museum from downtown or central Denver, take the U.S.
6 west to I-70 westbound to C-470 eastbound. Exit at the Morrison exit
and turn right into the town of Morrison. Proceed to the third traffic
light (Morrison only has three) and turn left (south) onto CO 8 for about
.34 mile. The Museum is on the right (west) side of the road. Not far south of Red Rocks, Mount Falcon is located astride the contact of the Precambrian crystalline rocks that form the rugged spine of the Front Range and the remains of the 300 million-year-old Ancestral Rocky Mountains, called the Fountain Formation. As you leave the trailhead, you cross the Fountain Formation. The contact with the Precambrian granite is elusive, but by careful inspection along the trail you should be able to pin the change in rock type to within a few feet. The mountain itself is made up of resistant Precambrian schist and granite. To reach Mount Falcon
Park's east entrance from Denver, take I-70 west to C-470 south and exit
at Morrison Road. Follow CO 8 through Morrison and south to the park's
east parking area and entrance. To reach Mount Falcon
Park's west entrance from Denver, take Hwy 285 to Indian Hills. Turn right
onto Parmalee Gulch Road and follow the brown signs.
North and South Table Mountains are here because the resistant cap rocks have impeded erosion. This cap rock is made of lava from vanished volcanoes. The flows have been radiometrically dated at about 63 million years old. Beneath the flows the sedimentary rocks are about 64-66 million years old. The Cretaceous-Tertiary boundary has been inferred by study of fossils. Evidence of dinosaurs, mammals, and crocodiles dating from the dawn of the age of mammals has been discovered here. To reach North and
South Table Mountains from Denver, take I-70 west to Hwy 58 in Golden.
West Bijou Creek has cut deep into the Denver Formation (D1 sequence) and formed a shallow but significant valley. This site is the only site in the Denver Basin where debris from the dinosaur-killing asteroid can be seen. The 100-foot-high bluffs also contain fossils of dinosaurs, turtles, crocodiles, mammals, plants, and insects. The West Bijou Creek
Site is open by appointment only. Contact the Plains Conservation Center
in Aurora. 15. Red Rocks Park and Amphitheatre The spectacular natural amphitheater at Red Rocks is arguably the best place to see the Fountain Formation. A brand-new visitor center at the top of the amphitheater provides history of the park and its concerts, but a short stroll allows the casual visitor to touch the massive rock that was deposited by gravelly rivers flowing off a mountain range 300 million years ago. The geological overlook on the spur road up to the amphitheater is a great place to get an overview of the Denver Basin. It is also possible to track the contact of the 300 million-year-old Fountain Formation and the 1.7 billion-year-old crystalline rock. The span of your hand covers a quarter of the earth's history. To reach Red Rocks Park and Amphitheatre from the north, take I-70 west to the Morrison exit (exit 259). Turn left and travel south 1.5 miles on CO 26 to the park entrance. To reach Red Rocks Park and Amphitheatre from the south, take Hwy 285 to C-470. Take the Morrison exit and travel west through the town of Morrison on Hwy 74 to the park entrance. To reach Red Rocks
Park and Amphitheatre from Denver International Airport, take Peña
Boulevard to 1-70 west to the Morrison exit, then south on CO 93. 16. Sand Creek Drainage, Bluff Lake Nature Center Sand Creek runs through
Bluff Lake Natural Area in Denver just before it connects to the South
Platte River in Commerce City. An interesting geologic fact about Bluff
Lake is that the bluffs were carved by Sand Creek. They are spectacular
40-foot-tall bluffs. Sand Creek crosses
much of the east side of Colorado Springs, running from Black Forest into
Fountain Creek north of Fort Carson. It runs just beyond Bluff Lake Nature
Center. 17. South
Platte Park, Carson
Nature Center The Carson Nature
Center at South Platte Park is very near the intersection of South Santa
Fe Drive (U.S. 85) and Mineral Avenue in Littleton. From that intersection,
proceed west on Mineral Avenue about .125 mile to the second right turn
and the first traffic signal into the RTD Park-N-Ride lot. Turn right
at that traffic signal and proceed north on South Platte River Parkway
through the Park-N-Ride lot. Head west at the first left turn. This yet-unnamed
road leads to the Carson Nature Center. This park is located west of C-470 along the hogback. The bedrock here is very close to the Cretaceous-Tertiary boundary, which is located just above the elevation of downtown Littleton. The valley fill is Ice Age-to-recent gravels while the valley floor is much older Cretaceous-Tertiary Denver Formation. Ice Age mammals are occasionally found in the stream banks. A mammoth tusk was collected just west of here in 1994. There are two trailheads to South Valley Park. One is off Ken-Caryl Ranch Road, and one is off of Deer Creek Canyon Road. For north access
from the metro area, travel south on C-470 and exit westbound on Ken Standley Lake is a reservoir that has flooded a valley cut into Late Cretaceous dinosaur-bearing Denver Formation (D1 sequence). Triceratops fossils have been found immediately to the north and south of the lake and a Tyrannosaurus rex tooth was found on the beach here in 1991. Standley Lake is
located at 8800 Kipling Street. To get there, take U.S. 6 west to the
CO 391 north Kipling Street exit. 20. Wheat Ridge Greenbelt Clear Creek flows through Wheat Ridge as the Greenbelt follows this creek. Wheat Ridge itself is a bluff of Paleocene Denver Formation (D1 sequence). The valley floor is covered with 1520 feet of sand and gravel deposited by Clear Creek. Gravel mining has created lots of shallow depressions, which have now filled with water and are lakes. The Denver Formation is often exposed in the bed of Clear Creek, where it is cut into a miniature canyonland. This is an excellent place to see the blue-green Denver Formation that was formed by the weathering of volcanic pebbles. Outcrops in this area contain dinosaur bones. The Wheat Ridge Greenbelt
is southwest of I-70 and Kipling. It is accessible from several trailheads
along this reach of Clear Creek from Youngfield Street to Harlan Street. Rock Park is a classic example of inverted topography. The cap rock is 34 million-year-old Castle Rock Conglomerate, and the shapes are formed by 55 million-year-old Dawson Arkose (D2 sequence). The Castle Rock Conglomerate is what remains of a powerful river that flowed down from the Front Range and onto the Denver Basin. The cobbles and sand in the streambed cemented together and became more resistant than the valley walls, which have eroded away. Now you climb the hill to get to the remains of the bottom of a 34 million-year-old valley. Near here, on the shoulder of I-25, a superb fossil rainforest was discovered in 1994. This 64.1 million-year-old forest is located in the Denver Formation (D1 sequence). Rock Park is located
just off of I-25 in Castle Rock. 22. Castlewood Canyon State Park The Cherry Creek drainage has cut down through the Late Eocene Castle Rock Conglomerate and exposed the soft underlying Eocene Dawson Arkose (D2 sequence). The visitor center is located on a resistant carapace of Castle Rock Conglomerate showing beautiful trough cross beds indicating the sediments were carried to the southeast. In the conglomerate, angular fragments of Castle Rock Rhyolite are common as are rounded fragments of granite. The conglomerate weathers into huge boulders that tumble down from the ledges and mantle into the inner canyons, thus disguising the underlying D2 sequence rocks. In the portion of the canyon downstream from the dam ruins, the flood associated with the breaking of the dam has revealed the alternating channel sandstone beds and overbank mudstone beds typical of the D2 sequence. To reach Castlewood
Canyon State Park, take CO 83 south approximately 5 miles past the intersection
with CO 86 at Franktown. 23. Cherokee Ranch Cherokee Ranch spreads across 3,105 acres rimmed with lofty bluffs of the Dawson Arkose (D2 sequence) that continue down from Daniel's Park to the north. From the ridges, look out to the west and south at Plum Creek and other tributary waters of the South Platte River that have eroded out the Chatfield Basin. Farther to the west you can see the red rocks of the Fountain Formation of Roxborough State Park. Along the skyline the uplifted Rocky Mountain range can be seen. To the southeast you can see other buttes topped by the youngest layers of the Denver Basin made up of the Dawson Arkose, Castle Rock Rhyolite, and Castle Rock Conglomerate. Imagine that these buttes were once all connected by one continuous surface before being eroded away. Cherokee Ranch is
accessible by appointment only. Access it by Daniel's Park Road from the
south via U.S. 85, or from I-25 via Castle Pines Parkway as you head west,
and then south on Daniel's Park Road. Columbine Open Space is 321 acres of public land located along the banks of Plum Creek south of Castle Rock. The rocks that form the bluffs to the east are Dawson Arkose (D2 sequence.) These bluffs are home to the only herd of Rocky Mountain bighorn sheep east of I-25. The flood of 1965 washed large amounts of sediment from these cliffs. Other bluffs to the north and west are capped with Castle Rock Rhyolite or Castle Rock Conglomerate. To visit Columbine
Open Space travel south from Castle Rock on the east I-25 frontage road
approximately 6 miles. A red barn is visible from the frontage road; turn
left and cross the one-lane bridge to the parking lot and trailhead for
1.5 miles of trail. 25. Daniel's Park This park provides one of the best vantage points overlooking the western fringe of the Denver Basin. Carefully venture to the edge of the rocks and gaze to the west. This entire valley had been sculpted by erosion, largely by Plum Creek, the small unassuming stream that flows past Sedalia. The rocks you are standing on were deposited by rivers carrying coarse sand and gravel from the rising Front Range. They are part of the Dawson Arkose and are a portion of the Eocene D2 sequence of sediments, which filled the Denver Basin during the Laramide mountain-building episode. To reach Daniel's
Park from Denver, travel south on I-25 to exit 188 (Castle Pines Parkway),
and go west to Daniel's Park Road. Turn right (north) and travel .5 mile
to the picnic area to view the overlook. You can travel north through
the park. You may also go south on Santa Fe Drive through Sedalia and
turn left onto Daniel's Park Road. Greenland Open Space (21,000 acres) is located on the northern margin of the Monument Divide, which separates the drainage of the Arkansas River to the south and the Platte River to the north. This is the highest terrain in the high plains, with Monument Hill attaining a maximum altitude of 7,400 feet. This height allows for the youngest layers of the Denver Basin to be exposed on the local butte tops. Three different rock layers cap the buttes in Greenland: the 55 million-year-old Dawson Arkose (D2 sequence,) the 36.7 million-year-old Castle Rock Rhyolite, and the 34 million-year-old Castle Rock Conglomerate. If you look carefully, the butte tops are the remnants of a once continuous surface. The "Rocky Mountain Surface" included the planed surface of the Rampart Range and the contiguous Denver Basin fill. This is strong evidence that no abrupt Front Range topography existed 34 million years ago. Public access, with
a continuation of the Santa Fe Trail, is scheduled for late fall of 2002.
Much of the landscape can presently be seen from the I-25 corridor. 27. Highlands Ranch Open Space Highlands Ranch was developed on a gentle north-facing slope to the north of a subtle escarpment. Parks above the escarpment like Daniel's Park and Cherokee Ranch are situated in the 55 million-year-old Dawson Arkose (D2 sequence). Highlands Ranch is built on the 64 million-year-old Denver Formation and Dawson Arkose (D1 sequence). The contract of D1 and D2, just below the escarpment, is marked by the presence of a red clay layer known as the Denver Basin Paleosol. Construction sites in Highlands Ranch are rich with 6564 million-year-old fossil leaves and wood. To reach Highlands
Ranch Open Space from Denver, take I-25 south to C-470 west. Take the
University, Broadway, Lucent, or Santa Fe exit from C-470 and go south.
Open-space areas may be viewed from many locals in Highlands Ranch as
you travel south. The Open Space Conservation Area (not accessible to
the public) is the southern boundary of HIghlands Ranch. 28. Nelson Ranch The Nelson Ranch can be found on the back side of the Dakota Hogback, which is topped with pine crested ridges and cut through by Indian and Rainbow Creeks. It lies on the south side of Roxborough State Park. The hidden valleys are striped and dabbled by dipping layers of the Fountain, Lyons, Lykins, Morrison (poorly exposed), Pierre (including the Niobrara Limestone), and Fox Hills Formations. Adjacent Carpenter Peak to the northwest exposes the 1.7 billion-year-old granite of the Front Range. Access to the Nelson
Ranch is currently through guided hikes by appointment. Future trail access
plans will be announced. North Willow Creek Ranch is 694 acres of rolling grassland to the north and east of Roxborough State Park. You may find evidence of Pierre Shale, Fox Hills Formation, Arapahoe Conglomerate, and Denver Formation. Present access to
North Willow Creek is by guided hikes. Trail plans will be announced in
the future. Cherry Creek winds through the upper valleys of Prairie Canyon Ranch, before passing through previously cut passages of the Late Eocene Castle Rock Conglomerate and exposed underlying Eocene Dawson Arkose (D2 sequence.) The Castle Rock Conglomerate in the canyons shows beautiful trough cross beds, indicating the sediments were carried to the southeast. You may also see alternating channel sandstone beds and overbank mudstone beds typical of the D2 sequence. In the conglomerate, angular fragments of Castle Rock Rhyolite are common as are rounded fragments of granite. Large blocks of rhyolite may also be seen on the hillsides to the left along the drive on your way into the ranch. Prairie Canyon Ranch
is located 6.5 miles south of Franktown on CO 83. This is 2 miles south
of the Castlewood Canyon State Park entrance. Access is by guided hike
only. This is one of the best places to view rocks on the Front Range. Beautiful tilted rocks expose the Fountain, Lyons, Lykins, Morrison (poorly exposed), Dakota, Pierre (including the Niobrara Limestone), and Fox Hills Formations. Adjacent Carpenter Peak exposes the 1.7 billion-year-old granite of the Front Range. The core of the park is the area between the Fountain and Dakota Hogbacks. Be careful to stay on the trails here as Roxborough has strict regulations prohibiting off-trail hiking. Family pets are not permitted in the park. To reach Roxborough State Park from Denver, take U.S. 85 (Santa Fe Drive) south to Titan Road. Turn right and go 3.5 miles. Turn left (still on Titan Road) and go 1.3 miles to an intersection, where the road turns into Rampart Range Road. Continue south for 2.4 miles, turn left on Roxborough Park Road, and turn right into the park entrance next to the fire station. From C-470 and Wadsworth,
go south on Wasdsworth to Waterton Road. Go east on Waterton Road to Rampart
Range Road, then go south on Rampart Range Road to Roxborough Drive. Turn
east on Roxborough Drive and make the first right into the park. Drive
2 miles to the parking lot and walk a short distance to the visitor center.
This park contains
splendid white bluffs of a feldspar-rich sandstone called arkose. The
rocks here are Late Cretaceous, about 67 million years old. If you look
closely at the rocks you can see that they are made up of small bits and
pieces of granitic rock, the same granite that makes up the towering massif
of Pikes Peak to the west. These sandstone bluffs are the remnants of
fans of coarse material deposited as the Rocky Mountains grew and shed
their overburden onto the plains. The processes of erosion continue today,
and you can see very similar gravelly and sandy material in the streams
draining from the modern mountains. Bear Creek Nature Center is located in Bear Creek Canyon. The two most prominent geologic formations at the Bear Creek Nature Center are the Niobrara Limestone and the Dakota Formation. There is contact with granite on the canyon. You can see all three formations as you look west from inside the Bear Creek Nature Center. To reach Bear Creek
Nature Center, take exit 141 from I-25. Go west on U.S. 24 to 26th Street.
Proceed south on 26th Street to Bear Creek Road. 34. Paint Mines Interpretive Park Paint Mines Interpretive
Park is located southeast of Calhan. The park 35. Fountain Creek Nature Center This park area is located along the drainage of Fountain Creek. There are good exposures of the Cretaceous Pierre Shale in the creek bed, and marine fossils confirm that these beds were deposited on the floor of an interior sea. Consider the forces of erosion that have made the broad valley in which you stand. This seemingly small stream, together with the Arkansas River and its tributaries, has sculpted this landscape and continues to do so. Fountain Creek Nature
Center is located south of CO 16. This To reach the nature
center from I-25, take exit 132, turn east on 36. Garden of the Gods Park and Visitor Center This spectacular
set of naturally sculpted rocks in Colorado Springs shows us the edge-on
view of the Denver Basin. The western backdrop of the park area is comprised
of the resistant Precambrian metamorphic and igneous rocks of Pikes Peak
and the Front Range. The principal exposures in the park are the Paleozoic
Fountain and Lyons Formations. The Fountain Formation makes up most of
the western part of the park's pinnacles and flatirons, and is made up
of sand and gravel beds derived from an ancient mountain range that predates
the Rocky Mountains. The Lyons Formation is generally a finer-grained
sandstone and makes up the marvelous linear ridges of the park. The most
prominent hogbacks soar to 300 feet. Close inspection reveals that the
Fountain and Lyons Formations actually interfinger in the park area, giving
geologists quite a challenge in making maps! Be sure to see the geologic
exhibits in the visitor center and pick up a detailed park map. 37. Palmer Park This extensive urban
natural park is made of coarse gravels derived from erosion of the Pikes
Peak area. The top of Palmer Park gives superb views of Pikes Peak and
an interestingly diminished view of the Garden of the Gods, as the peak
towers 8,000 feet over the Garden. Palmer Park's rocks are called the
Dawson Arkose (D1 sequence) and are of Late Cretaceous age, about 66 million
years old. The granular rock is resistant to erosion and forms the steep-walled
battlements and scarps. Beneath the white cliffs are olive-brown mudstone
and sandstone beds made up largely of volcanic debris. The rocks tell
us that a cover of volcanic rocks was eroded off the mountains to the
west before the Pikes Peak granite was exposed. 38. Pulpit Rock Park The distinctive white
spire that gives this park its name is made of coarse gravels derived
from erosion of the Pikes Peak area. These rocks are called the Dawson
Arkose (D1 sequence) and are of Late Cretaceous age, about 66 million
years old. The granular rock is resistant to erosion and forms the steep-walled
battlements and scarps. Beneath the white cliffs are olive-brown mudstone
and sandstone beds made up largely of volcanic debris. The rocks tell
us that a cover of volcanic rocks was eroded off the mountains to the
west before the Pikes Peak granite was exposed. 39. Rampart Park Rampart Park is one
of the more subtle geologic parks in Colorado Springs. Covered mainly
by ball fields, this park is also endowed with dozens of petrified logs.
These logs are exposed in banks and cliffs along the western margin of
the park. Remember that it is illegal to collect fossils from Front Range
parks. 40. Starsmore Discovery Center at North Cheyenne Canyon Park This park is located
on the southwestern side of Colorado Springs at the base of North Cheyenne
Canyon. The walls of the canyon are carved into the Pikes Peak massif
and show elegant outcrops of the Precambrian granite that makes up the
Front Range. 41. Ute Valley Park Ute Valley Park has
excellent exposures of the Fox Hills and Laramie Formations that form
a steeply dipping ridge along the western margin of the park. Dinosaur
footprints, though subtle, are common along this ridge. The grassy fields
that form the bulk of this park are underlain by the easily weathered
andesitic basal layers of the Dawson Formation (D1). 42. Dinosaur Depot Dinosaur Depot Museum is located on U.S. 50 in Cañon City. Information can be gathered here about the superb geologic exposures in Fremont County, Colorado (especially well known for its dinosauriferous Morrison Formation outcrops in the Garden Park Fossil Area), Dinosaur Trackway on Skyline Drive (in the Dakota Group, beachfront of the Western Interior Sea), and the Royal Gorge Bridge and Park (superb exposures of Precambrian igneous rock). To reach Dinosaur
Depot from Denver, take I-25 south. Take exit number 140B. Merge onto
east Arvada Street. Turn right onto South Nevada Avenue. Stay straight
to go onto CO 115 south. Take the U.S. 50 west ramp. Merge onto U.S. 50
west for about 11 miles. 43. Betasso Preserve This park has exposures of Precambrian igneous rocks, the underpinning of the Front Range of the southern Rocky Mountains. At about 1.7 billion years old, this Boulder Creek Granodiorite is one of the oldest rock types in Boulder County (or along the Front Range). The best exposure of the Boulder Creek Granodiorite is at the end of the short Bummer's Rock Trail, which overlooks Boulder Creek and the canyon that it carved. Betasso Preserve
is located 6 miles west of Boulder. Take Boulder Canyon west to Sugarloaf
Drive, turn right onto Betasso Drive, main entrance to park is on the
left. Bummer's Rock trailhead is just past the main park entrance on the
right. All groups of 25 persons or more visiting BCPOS parks are required
to obtain a group permit. The free permits may be obtained by calling
303-441-3950, MondayFriday, between 8:00 A.M.4:30 P.M. The Boulder Flatirons are the stereotypical example of tilting mountain front layers of the Fountain Formation. These remnants of the Ancestral Rockies are now favorite rock climbing sites. Traction is provided by the coarse granules and pebbles derived from erosion of ancient mountains. Access to the Third Flatiron may be seasonally prohibited to protect nesting falcons. The Boulder Flatirons
stand at the western edge of town near Chautauqua Park on Baseline Road.
45. Contact Corner This spot has a marvelous exposure of a contact between two rock types. This is called an unconformity. The Fountain Formation sedimentary rocks lie on top of the Precambrian igneous rocks. Over 1 billion years of rock layers are missing from the record at this boundary! Contact Corner is
located about 3 miles up Flagstaff Road. 46. Crown
Rock/Flagstaff Sill Crown Rock/Flagstaff
Sill is located about 2.5 miles up Flagstaff Road. 47. Eldorado Canyon State Park Eldorado Canyon has spectacular exposures of Precambrian metamorphic rocks of the Front Range and the overlying sedimentary rocks. This is a major spot for rock climbers who climb on the Precambrian crystalline rocks as well as the overlying Fountain and Lyons Formations. Beyond the mouth of the canyon are subtle exposures of the Morrison Formation and a large hogback of the Dakota Sandstone. To reach Eldorado
Canyon State Park, drive 4 miles south on CO 93, turn west on CO 170,
and drive 4 miles through Eldorado Springs to the park entrance. Crescent
Meadows can be reached by automobile. From the junction of CO 93 and CO
72, drive west on CO 72 for 8 miles until you reach Crescent Park Drive.
Turn right on Crescent Park Drive and drive 1 mile to an intersection
with Gross Dam Road (dirt road). Turn right and continue for 1.7 miles
across the railroad tracks to the park entrance. Located west of the town of Lyons, this scenic area has distinctive outcrops of Lyons Sandstone. This area has remains of quarries where the Lyons sandstone was extracted for use as building material. The parking area at this park is located in a natural bowl eroded into the Fountain Formation. Located above the reddish purple sandstone layers, the distinctive ridge-capping unit is the Lyons Sandstone. This city park also has beautiful exposures of cross-bedded Lyons Sandstone, the remains of fossilized sand dunes. The entrance to Hall
Ranch is found on CO 7, 1 mile west of Lyons. No dogs are allowed at Hall
Ranch Open Space. All groups of 25 persons or more visiting BCPOS parks
are required to obtain a group permit. The free permits may be obtained
by calling 303-441-3950, MondayFriday, between 8:00 A.M.4:30
P.M. 49. Heil Valley Ranch Open Space The trails at Heil Valley Ranch wind their way through millions of years of sedimentary rocks, in a scenic valley between erosion-resistant ridges of Lyons Sandstone on the west and the Dakota Formation to the east. The entrance to Heil
Valley Ranch is located on Geer Canyon Road off of Left Hand Canyon Road
northwest of Boulder. No dogs are allowed at Heil Valley Ranch.All groups
of 25 persons or more visiting BCPOS parks are required to obtain a group
permit. The free permits may be obtained by calling 303-441-3950, MondayFriday,
between 8:00 A.M.4:30 P.M. 50. Marshall Mesa This is an old Laramie Formation coal mining area where it is possible to see the remains of old mine sites along the north side of the valley. Irrigation ditches expose coal, carbonaceous shale, and Foxhill Sandstone layers. The rock units are broken by a series of faults making the normal layer cake pattern into a series of broken ridges and valleys. Marshall Mesa is
located south of Boulder on CO 93. 51. National Center for Atmospheric Research Trailhead to Mallory Cave This trail provides a superb transect from the Pierre Shale through the entire geologic section up to the Fountain Formation. Entry to Mallory Cave may be seasonally prohibited to protect a rare colony of breeding bats. The trailhead starts
at a cap rock-protected boulder-strewn mesa by the NCAR building. 52. Rabbit Mountain Open Space As you approach this park you pass a mine where layers of calcareous shale are being quarried. These shale beds occur near the base of the Cretaceous Interior Seaway marine sediments and are the raw material for cement. The shale is very easily eroded and form the floor of the valley. This park presents a beautiful series of cliffs and escarpments defined by the resistant Dakota Sandstone. The park is located at the boundary between the high plains and the foothills of the Rockies. The faults that define this physiographic boundary cut through the park. A fold in the Dakota Sandstone layer is visible from the parking lot and as you walk up the trail you may find highly polished fragments of sandstone, the polished surfaces having been created by the faults defining the margin of the Denver Basin. Near the north end of the park there are chert pebble conglomerates in the lowest part of the Dakota Sandstone. These pebbles are very resistant to erosion and are believed to have been brought here by Cretaceous-age rivers from Utah. Rabbit Mountain Open
Space is located on North 53rd Street, about 15 miles north of Boulder
off of CO 66 approximately 2 miles east of Lyons. All groups of 25 persons
or more visiting BCPOS parks are required to obtain a group permit. The
free permits may be obtained by calling 303-441-3950, MondayFriday,
between 8:00 A.M.4:30 P.M. 53. Settler's Park This park has beautiful fins of Paleozoic Fountain Formation that you can walk around and climb on. Note that the coarse sandstone is made up of fragments of an old granitic mountain range. Settler's Park is
located on Canyon Boulevard just as you are leaving Boulder to the west.
Settler's Park is the trailhead for the Red Rocks area. 54. Valmont Dike Valmont Dike is one of the few easily visible volcanic features in the Boulder area. Volcanic rock oozed up in cracks in the Pierre Shale. This magma formed a rock that is much more resistant to erosion than the Pierre Shale. As the soft surrounding rock eroded away, the hard igneous rock was exposed as a ridge. It is located east of Boulder on Valmont Road near the Stazio ball fields and is visible from all over the Boulder Valley. Valmont Dike is privately owned and not directly accessible. 55. Devil's
Backbone Devil's Backbone
is located off of U.S. 34 west of Loveland. Turn north on Glade Road off
U.S. 34 and follow the signs. Horsetooth Reservoir lies in a north-south valley that formed between the Lyons Sandstone to the west and the Dakota Hogback to the east. The easily weathered Lykins and Morrison Formations form the valley that is now filled with water. At low water levels, the Morrison Formation is exposed and bones of a dinosaur related to Allosaurus were recently collected here by the Denver Museum of Nature & Science. Horsetooth Mountain is made up of Precambrian igneous and metamorphic rock and makes the ridge west of the reservoir. Horsetooth Mountain
Park is located on the west side of Horsetooth Reservoir. It is located
4 miles from Fort Collins and 12 miles northwest of Loveland. 57. Lory State Park Lory State Park lies to the north west corner of Horsetooth Reservoir and is contiguous with Horsetooth Mountain Park. Lyons Sandstone and the Dakota Hogback are on the eastern part of the park, while Precambrian igneous and metamorphic rocks are on the western part of the park. The easily weathered Lykins and Morrison Formations form the valley that is now filled with water. At low water levels, the Morrison Formation is exposed and bones of a dinosaur related to Allosaurus were recently collected here by the Denver Museum of Nature & Science. Horsetooth Mountain is made up of Precambrian igneous and metamorphic rocks and makes the ridge west of the reservoir. To reach Lory State
Park, take U.S. 287 north from Fort Collins through LaPorte, then turn
left at the Bellvue exit onto CR 23N. Turn left again, go 1.4 miles, and
take a right on CR 25G. Drive another 1.6 miles to the park entrance.
The striking rimrock outcrops that give this Larimer County Open Space its name include Ingleside Sandstone (Permian), Lyons Sandstone (Permian), and Lytle Formation (Cretaceous). Rimrock Open Space
will be open to public access beginning fall 2002. The open space at that
time can be accessed via the Coyote Ridge Natural Area trailhead off of
CR 19, southwest of Fort Collins. Coyote Ridge Natural Area is a dynamic and special place. Spanning over 1,000 acres, Coyote Ridge is an area of transition between the prairies and mountains. Along the two-mile trail there are good places to view the Niobara and Dakota Formations, and from the top of the second hogback ridge you can see Lyons Sandstone, the Fountain Formation, Devil's Backbone, and Rimrock Open Space. Coyote Ridge is on
the west side of Taft Hill Road, .5 mile south of Trilby Road. ![]() |
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