Colorado Porch

Tag

geology

26 Porch Notes tagged “geology,” from counties across Colorado.

Water and land - La Plata County

In La Plata County, groundwater is not the same everywhere

Whether a La Plata County property can rely on a domestic well depends heavily on the local geology, which varies a lot across the county.

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Home and property - El Paso County

In Colorado Springs and Black Forest, the ground can lift a foundation

Expansive clay and dipping bedrock around Colorado Springs and Black Forest can lift a foundation, so a soils report is normal homework before you buy.

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Home and property - Pueblo County

Expansive clay soils are a real Pueblo-area home question

Parts of the Front Range piedmont around Pueblo have clay-rich soils that swell when wet and shrink when dry, which is worth understanding before buying or building.

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Water and land - Gunnison County

Black Canyon's dark walls are nearly two-billion-year-old rock

The steep, dark walls of Black Canyon of the Gunnison are ancient Precambrian gneiss and schist laced with pink pegmatite dikes, cut into a narrow gorge by the Gunnison River.

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Outdoors and wildfire - Boulder County

Rabbit Mountain marks the foothills reaching out onto the plains

At Ron Stewart Preserve, Rabbit Mountain marks the easternmost point of Boulder County's foothills, where rock meets the open plains.

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Water and land - Boulder County

The Flatirons are tilted slabs of an old sandy plain

Boulder's signature Flatirons are slabs of Fountain Formation sandstone that were laid down flat, then tipped on edge when the Rocky Mountains rose.

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Water and land - Douglas County

The rock that named Castle Rock was hardened by volcanic silica

The flat-topped butte over Castle Rock is capped by erosion-resistant Castle Rock Conglomerate, bound by silica cement that formed from ancient volcanic ash.

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History and culture - Jefferson County

The free Golden museum with a moon rock and a room of glowing stone

On the Colorado School of Mines campus, a free earth-science museum holds an Apollo 17 moon rock, a cave of glowing minerals, and tens of thousands of specimens that explain why Golden became a mining town.

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Water and land - Mineral County

An ancient supervolcano helped shape Mineral County's mountains

Much of the rock around Creede formed during enormous volcanic eruptions tens of millions of years ago, including the La Garita supervolcano's blast, and that origin still shapes today's peaks, cliffs, and rock shapes.

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Water and land - Chaffee County

The Chalk Cliffs below Mount Princeton are not made of chalk

The pale Chalk Cliffs on the flank of Mount Princeton are altered granite, tied to the same underground heat that feeds the area's hot springs along Chalk Creek.

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History and culture - Huerfano County

The Spanish Peaks and their stone dikes are the county's landmark

The twin Spanish Peaks and the long stone walls radiating from them are a well-known geologic feature in Huerfano County, and the Highway of Legends byway runs through the country around them.

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History and culture - Mineral County

Walk Inside an 1891 Silver Mine on Creede's Amethyst Vein

The Last Chance Mine near Creede lets you walk inside a real 1891 silver mine and see purple amethyst still in the rock wall.

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Water and land - Moffat County

Irish Canyon: a short drive through deep time on the way to Browns Park

A narrow red, green, and gray canyon off Highway 318 packs layered rock and Fremont-era petroglyphs into one easy stop before Browns Park.

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History and culture - Prowers County

Lamar's gas station built from petrified wood

On Main Street in Lamar, a 1932 service station built from local petrified wood makes a free, two-minute stop where the walls themselves are a geology lesson.

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History and culture - Jefferson County

The long red ridge along the foothills is the Dakota Hogback

The steep, tilted ridge that runs north-south at the edge of the foothills is the Dakota Hogback, and creeks cut narrow gaps through it where roads now pass.

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Water and land - Saguache County

The whole La Garita country was shaped by one enormous eruption

Wheeler's pale spires, Penitente Canyon's walls, and much of western Saguache County's rock come from a huge ancient volcanic eruption.

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Outdoors and wildfire - Saguache County

La Garita Wilderness and the Wheeler Geologic Area are hard to reach on purpose

The La Garita Wilderness in the Rio Grande National Forest holds the volcanic spires of the Wheeler Geologic Area, which you reach only by a long hike or a rough four-wheel-drive road.

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Water and land - Huerfano County

Lone rock towers near La Veta are old volcanic plugs

Isolated rock towers like Goemmer Butte near La Veta are the hardened cores of old volcanic vents, left standing after softer ground wore away.

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Outdoors and wildfire - Larimer County

Red Mountain Open Space closes in winter for wildlife and bans dogs

Red Mountain Open Space, a large area of red rock and grassland near the Wyoming line, is open only part of the year to protect wintering wildlife, and it does not allow dogs.

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Water and land - Montrose County

The Black Canyon's walls are some of the oldest rock in Colorado

The dark, striped cliffs of Black Canyon of the Gunnison near Montrose are nearly two-billion-year-old Precambrian rock, laced with pink pegmatite that gives the Painted Wall its name.

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Outdoors and wildfire - Larimer County

The Devil's Backbone is a tilted rock fin west of Loveland

Devil's Backbone Open Space protects a hogback, a wall of sedimentary rock that the same forces that built the Rockies tipped on edge, and it is a popular trail area close to town.

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Water and land - Las Animas County

The stone walls radiating from the Spanish Peaks are famous volcanic dikes

The long rock ridges that fan out from the base of the Spanish Peaks are radial dikes, hardened sheets of igneous rock left when molten material filled cracks and the softer ground around them wore away.

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Water and land - Mineral County

Wagon Wheel Gap is a narrow rock gateway with its own geology story

Wagon Wheel Gap, where the Rio Grande squeezes through a rock narrows southeast of Creede, sits on the edge of an ancient volcanic caldera and has an interpretive site explaining its geology and old fluorspar mining.

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Water and land - Grand County

The Never Summer Mountains are the young volcanic edge of the park

The Never Summer Range west of Grand Lake is made of volcanic rock far younger than the ancient granite that forms most of Rocky Mountain National Park.

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Water and land - La Plata County

Warm springs north of Durango come from faults in the Animas Valley

The thermal springs along the Animas Valley north of Durango, including the Pinkerton and Trimble springs, are fault-controlled geothermal features studied by the Colorado Geological Survey.

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Outdoors and wildfire - Park County

Eleven Mile Canyon cuts through Pikes Peak granite below the dam

Below Eleven Mile Reservoir near Lake George, the South Platte carved a steep canyon through Pikes Peak granite, now a forest recreation area on an old railroad grade with a day-use fee.

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