Case Study: Big Thompson Flood

On July 31, 1976, a powerful thunderstorm over Colorado’s Big Thompson Canyon unleashed a deluge that became one of the state’s most catastrophic natural disasters. Known as the Big Thompson Flood, this event claimed 144 lives, caused significant damage to infrastructure, and left a lasting impact on both the physical and social landscapes. This flood serves as a case study of the interplay between geologic conditions, meteorology, and human activity in a high-risk environment.

Front page of the Rocky Mountain News following the catastrophic flood in Big Thompson Canyon in August of 1976.
Front page of the Rocky Mountain News following the catastrophic flood in Big Thompson Canyon in August of 1976.

The Meteorological Trigger

The Big Thompson Flood was caused by an intense, stationary thunderstorm that dropped more than 12 inches of rain in just four hours over the steep canyon. The localized nature of the storm, combined with its high rainfall intensity, overwhelmed the Big Thompson River’s drainage system. This type of weather event is not uncommon in Colorado, where summer thunderstorms can deliver large amounts of precipitation over short periods. The semi-arid climate, combined with the region’s high topographic relief, creates conditions that are particularly conducive to flash flooding.

Thunderstorms of this magnitude occur when warm, moist air is forced upward by the mountainous terrain, cooling and condensing into heavy rainfall. In the case of the Big Thompson Flood, the storm’s stationary position ensured that all the precipitation fell within a confined area, greatly intensifying the flood’s impact.

Geological Setting of Big Thompson Canyon

Big Thompson Canyon, located in the Rocky Mountains of northern Colorado, is a steep and narrow valley carved over millions of years by the Big Thompson River. The canyon’s geology is dominated by granitic bedrock interspersed with loose sediments and colluvium, materials that are easily mobilized during heavy rainfall. The steep canyon walls and limited floodplain amplify the destructive potential of flash floods, as water rapidly accumulates and accelerates downhill.

House precariously undercut by lateral scour on the Big Thompson River a quarter of a mile below Glen Comfort, Larimer County, August 1976. Photo credit: Ralph Shroba.
House precariously undercut by lateral scour on the Big Thompson River a quarter of a mile below Glen Comfort, Larimer County, August 1976. Photo credit: Ralph Shroba.

One of the key factors in the severity of the 1976 flood was the canyon’s geomorphology. The steep gradient of the river increased the velocity of the floodwaters, allowing them to carry massive amounts of sediment, debris, and rock. This debris flow not only caused direct damage but also increased the erosive power of the water, undercutting slopes and triggering landslides that further contributed to the destruction.

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Case Study: Lykins Formation

Small but significant areas of Colorado are underlain by bedrock that is composed of evaporative minerals. These are salts and sulfates that precipitate out of salt-concentrated surface waters. In the geologic past these minerals were deposited in shallow seas within closed or restricted basins where the seawater evaporation rate exceeded the replenishing supply. Current environments that are similar include the Great Salt Lake in Utah and the Dead Sea in the Middle East. These minerals are predominantly anhydrite (CaSO4) and halite (rock salt – NaCl) at depth, and gypsum (CaSO4*H2O) near the surface. Over geologic time, the evaporative minerals filled the sea basins and were subsequently buried beneath younger sediments. Through burial diagenesis, these deposits become evaporite bedrock. After the Rocky Mountains rose, millions of years of subsequent erosion and downcutting of rivers has now exposed some of these evaporite rocks at the surface.

Two characteristics of evaporite bedrock are important. One is that evaporite minerals can flow, like a hot plastic, under certain pressures and temperatures. The second, and most important to land use and development, is that evaporite minerals dissolve in the presence of fresh water. It is this dissolution of the rock that creates caverns, open fissures, streams outletting from bedrock, breccia pipes, subsidence sags and depressions, and sinkholes. These landforms are described collectively as karst morphology. Karst morphology originally referred to limestone areas known for characteristic closed depressions, sinkholes, caverns, and subterranean drainage. Evaporite karst comprises similar morphology where these features develop as a result of dissolution of the evaporite minerals.

One example of evaporative bedrock in Colorado is the Permo-Triassic Lykins Formation redbeds that contain massive gypsum deposits, up to 50 feet (15 m) thick. Dissolution of those beds and some of the thin algal limestone within the unit is responsible for many sinkholes and ground subsidence features inside the main Dakota Sandstone hogback that marks the boundary of the Eastern Plains and the Front Range.

Munroe Quarry near Livermore, Colorado in Larimer County, which produces gypsum from the Permo-Triassic Lykins Formation. Photo credit: Colorado Geological Survey." width="600" height="395" /></a> Munroe Quarry near Livermore, Colorado in Larimer County, which produced gypsum from the Permo-Triassic Lykins Formation.
Munroe Quarry near Livermore, Colorado in Larimer County, which produces gypsum from the Permo-Triassic Lykins Formation. Photo credit: Colorado Geological Survey.

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field work: witness

field work: witness, female greater sage-grouse (Centrocercus urophasianus), Upper Pool Creek, Dinosaur National Monument, Colorado, October ©2024 hopkins/neoscenes.
field work: witness, female greater sage-grouse (Centrocercus urophasianus), Upper Pool Creek, Dinosaur National Monument, Colorado, October ©2024 hopkins/neoscenes.

In the process of phonographic listening/recording along Upper Pool Creek west of the Chew Ranch property, I came across this scenario. No clues as to what led up to it. The body seemed to be fresh and whole, life gone that very day perhaps? I didn’t disturb the scene: doubtful that such a nutrient/energy source would remain unconsumed in this wild environment for long.

It did bring back the memory of traveling to Dinosaur back in 1988 with Pablo where we visited his friend Renzo and wife Lisa. Renzo had recently taken the position of wildlife manager for 40,000 sq mi of the Monument and northwest Colorado. One morning, pre-dawn, we set out in his work truck and after a long drive, parked in the low sagebrush steppe and from a distance watched, in the greying Light, a lek where the dramatic mating ritual between dominant male and female Greater sage-grouse unfolded.

flash-flooding

On the afternoon of 27 August 2024, the area including Upper Sand Canyon, a relatively small drainage in Dinosaur National Monument, experienced a major precipitation event. The fifteen mile Echo Park access road, in part, runs the full length—about three miles—down that canyon, much of it in the fluvial hazard zone. Long stretches of the road were completely washed out, and it was only the heroic efforts of the guy re-grading it that re-opened access to Echo Park some days later. I recently made it back up to Dinosaur for a short sojourn after an interminable and blurry five-year absence.

Earlier bush-walks along the dry washes in the area, the curious effects of flash-flooding as well as other, slower, changes are noted. I’ve come across dried-mud-caked trees in Upper Pool Creek Canyon more than 20 feet higher than the dry creek bed, yikes! And in some areas of Hells Canyon, boulders the size of small cars are seen piled up and ground together in violent proximity.

With the 27 August incident in mind I did a long bush-walk along the east-west axis of the Ruple Point-Red Rock Anticline that forms the Weber Sandstone hogbacks running perpendicular to Upper Sand Canyon.

Looking upstream into the scoured wash of Upper Sand Canyon, Dinosaur National Monument, Colorado, October ©2024 hopkins/neoscenes.
Looking upstream into the scoured wash of Upper Sand Canyon, Dinosaur National Monument, Colorado, October ©2024 hopkins/neoscenes.

Looking downstream, close to the egress from Upper Sand Canyon where the force of the water pushed a large juniper tree right over. Never underestimate the force of moving water! Dinosaur National Monument, Colorado, October ©2024 hopkins/neoscenes.
Looking downstream, close to the egress from Upper Sand Canyon where the force of the water pushed a large juniper tree right over. Never underestimate the force of moving water! Dinosaur National Monument, Colorado, October ©2024 hopkins/neoscenes.
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on Mesa Creek

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on Clear Creek

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Light on water

Light on water, near Bonham Reservoir, Grand Mesa, Colorado, September ©2024 hopkins/neoscenes.
Light on water, near Bonham Reservoir, Grand Mesa, Colorado, September ©2024 hopkins/neoscenes.

or …

Light on water, near Bonham Reservoir, Grand Mesa, Colorado, September ©2024 hopkins/neoscenes.
Light on water, near Bonham Reservoir, Grand Mesa, Colorado, September ©2024 hopkins/neoscenes.

Experimental Conviction

Long life is one of the greatest Blessings that we Mortals can enjoy; it being what all Men naturally desire and wish for. Nay, when Men are come to the longest Date, they desire yet to live a little longer. But, however, Health is that which sweetens all our other Enjoyments, without which the longest Life would be no more than a living Death, and render us burdensome to our selves, and troublesome to all about us.

But though Life be so desirous, and Health so great a Blessing, yet how much is both the one and the other undervalued, by the greatest Part of Mankind? Whatever they may think or say of the inestimableness of those precious Jewels, yet ’tis plain, by their Practice, that they put the Slight upon, and despise them both; and the most Man are hardly sensible of the worth of Health, ’till they come in good Earnest to be deprived of it.

How many Men do we daily see, by their Intemperance and Excess, to lay the Seeds of future Distempers, which either carry them off in the flower of their Age, which is the Case of most or else render their Old Age, if they do arrive to it, uneasy and uncomfortable? And though we see others daily drop into the Grave before us, and are very apt with Justice to ascribe the Loss of our Friends, to their living too fast, yet we cannot forbear treading in the same Steps, and following the same Courses, ’till at last, by a violent and unnatural Death, we are hurried off the Stage of Life after them.

What the Noble Cornaro observes of the Italians of his Time, may very well be applied to this Nation at present, viz. “That we are not contented with a plain Bill of Fare; that we ransack the Elements of Earth, Air, and Water, for all sorts of Creatures to gratify our wanton and luxurious Appetites: That as if our Tables were too narrow and short to hold our Provisions, we heap them up upon one another. And lastly, That to create a false Appetite, we rack our Cook’s inventions for new Sauces and Provocations to make the superfluous Morsel go down with the greatest Gust.”

This is not any groundless Observation, but it carries an Experimental Conviction along with it. Look into all our publick Entertainments and Feasts, and see whether Luxury and Intemperance be not too predominant in them. Men, upon such Occasions, think it justifiable to give themselves the Loose, to eat heartily, and to drink deeply; and many think themselves not welcome, or well entertained, if the Master of the Feast be so wise as not to not give them an Occasion of losing the MAN, and assuming the BEAST.

Cornaro, Luigi. Sure and Certain Methods of Attaining a Long and Healthful Life. London, UK: Daniel Midwinter, 1722.

on Ward Creek

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watching Hells Kitchen

watching Hells Kitchen, Cedaredge, Colorado, August ©2024 hopkins/neoscenes.
watching Hells Kitchen, Cedaredge, Colorado, August ©2024 hopkins/neoscenes.

[ED: The far horizon is a portion of Grand Mesa at over 10,000 ft, and the side of the mesa facing the viewer, an area characterized by numerous landslides, is called “Hells Kitchen.” This is the view from my kitchen.]

on Kannah Creek

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on Coal Creek

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on Anthracite Creek

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every form of being

To every form of being is assigned
An active principle:—howe’er removed
From sense and observation, it subsists
In all things, in all natures: in the stars
Of azure Heaven, the unenduring clouds,
In flower and tree, in every pebbly stone
That paves the brooks, the stationary rocks,
The moving waters and the invisible air.
Whate’er exists hath properties that spread
Beyond itself, communicating good,
A simple blessing, or with evil mixed:
Spirit that knows no insulated spot,
No chasm, no solitude; from link to link
It circulates, the soul of all the worlds.

William Wordsworth. The Excursion: Wisdom Is Oftentimes Nearer When We Stoop than When We Soar. Portable Poetry, 2015. Book VI, 1-15.

extinction

Consider the sum of all life, the heaped arrays of adaptations flung one after the next into the abundance of forms, each possessing codes pertaining only to its ancestors and its immediate predecessors, teeming organisms hefting around history in their cells, a library of each quirk and evolutionary indecision of the past 3.5 billion years, but only a record in each species of its single divergence from the source, with no register of errors or chance events gone awry because those were discarded to extinction, leaving a peculiar animal honed to a perfect set of symbols and codices, down to the Sonoran topminnow (Poeciliopsis occidentalis), perhaps soon to be vanquished from the planet. Protecting species is the same intrinsic gesture as preserving the original documents and constitutions of an entire civilization, or the love letters of grandparents.

Childs, Craig Leland. The Secret Knowledge of Water: Discovering the Essence of the American Desert. 1st paperback ed. Boston, MA: Back Bay Books, 2001.

NASA Earth Observatory

One of my favorite online feeds is from the NASA Earth Observatory along with their Image of the Day. After catching a recent article on the San Luis Valley, I thought that subscribers might be interested in some of the incredible material that NASA offers on a daily basis. This includes front-line data used in climate research.


“The Earth Observatory’s mission is to share with the public the images, stories, and discoveries about the environment, Earth systems, and climate that emerge from NASA research, including its satellite missions, in-the-field research, and models.”


An expansive view of most of Colorado looking from the south-south-west from the International Space Station (ISS). Photo credit: NASA.
An expansive view of most of Colorado looking from the south-south-west from the International Space Station (ISS). Photo credit: NASA.

The Details

Earth Observatory GIS browserA global map index of thousands of images—one can go direct to Colorado and see more than seventy feature articles covering natural hazards, geology, atmospheric science, and other subjects.

Global MapsA wide range of maps compiled from satellite data.

Feature ArticlesCovering many important topics such as remote sensing, atmosphere, snow & ice, water, and life.

NASA EO blogsIncredibly informative nuggets of research into the natural world, including several topical blogs:

Earth MattersIncludes in-depth reports on everything from Astronaut Photography to Where on Earth?

Notes From the FieldStories about how NASA conducts its scientific work and the technologies that make it all possible.

EO KidsWritten for audiences aged 9 to 14, it has many educational features.

Climate Q&AIncludes in-depth answers to common questions about the global climate.

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note to self

I’m no photographer. I take pictures, mostly rather banal pictures: re-creations, re-presentations, documentations of reality. When asked, I tell people that I photograph who I am with, what I am doing, and where I am. Suitably self-centric for the pseudo-artist.

Yes, I show up, with camera. And back when there was a physical craft involved, I excelled in the production of fine archival prints, and I was called a Master Printer. Over the years I taught many courses on the craft: master printing, photographic history, and photography. I have thousands of vintage silver, silver/sepia, and silver/selenium prints that have sat in boxes for the decades since I was last in a wet darkroom, plying that craft.

I still hold onto a selection of superb enlarger lenses, though the last enlarger I had access to—in the darkroom that I built for my father—I gave to the local college back in 2002. Their once-vibrant photography program collapsed a few years later. So much for craft, gotta sell those lenses.

oceanic detritus, Dritvík, Iceland, May ©2024 hopkins/neoscenes.
oceanic detritus, Dritvík, Iceland, May ©2024 hopkins/neoscenes. [Ed: and, no, that’s not a Lego, it’s 2-meters (7 ft) tall.]
However, in terms of an evolution of seeing, the eye, not much has changed: perhaps nothing. While specific subjects change, the overarching captures are repetitive and … banal … both in formal compositional metrics as well as the ways that the subjects are engaged. No evolution at all.

Not only that, I still can’t get a true horizontal horizon line! Dammit! Simple composition, strictures I never liked, were not transcended to a level where they could intentionally be disposed of entirely.

After five years of not carrying an analog 35mm camera, shooting only miniDV video from 2000 through 2006, I picked up a DSLR with a lens that gradually reduced itself over more than a decade’s use to a piece of garbage. And forget a clean CCD sensor. It’s worse than in the ‘old times’ with spurts of Dust-Off and manually spotting (or ‘re-touching’) negatives and prints with Spotone and tiny paint brushes. CCDs manifest every dust speck as large dark circles on the screen (and in print). Got a clear sky? Guaranteed to be covered in more-or-less distinct circular blobs. I finally upgraded to a true professional-grade DSLR a few years back—as usual, behind the current mirror-less technology—always several steps behind any state-of-the-art. The only time I was near that was when I was shooting with the two Nikon F2a bodies and a selection of decent lenses that my father generously handed down to me back in the late 1970s.

The successful Kickstarter campaign in 2013 to acquire a high-end large-format printer ended during Covid when—after seven years of pointless printing—one nozzle got clogged and I didn’t immediately address the issue to fix it. The printer is now a 250-pound paperweight. I could perhaps revive it, but that would require buying a full set of inks, a $2500 investment that might not pay off in the end. I only sold a handful of prints total, and gave away many more than that, by far.

At this point, my images are hardly ‘collectible’ and so the only photographic medium I am using currently is this travelog. That will not change for the duration—despite this virtual world already jam-packed with trillions of images—until the energy winds down, and all archives become cold stardust fodder.

airport bathroom

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Case Study: NARD

[ED: I decided to re-work and re-publish some of the public-domain articles that I compiled and wrote for the CGS as they are no longer updating the widely-read >RockTalk<  blog that I established for them back in 2016.

Public interest regarding human-caused water pollution from abandoned mines remains high following the Gold King Mine event in 2015. Complicating the overall water-quality issue is the presence of natural pollution sources that affect the baseline condition of many watersheds across the state. These areas are often accompanied by obvious surface indicators as depicted in the photos.]

Are so-called pristine mountain waters always clean and pure? Can streams unaffected by human activities and livestock influences be unfit for human consumption, or for aquatic life? The existence of natural acid rock drainage (NARD) suggests a “no” to the former, and a “yes” to the latter question.

But what exactly is NARD? 

more “Case Study: NARD”

on the Uncompaghre

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field work

The San Juan Mountains from CR-12, Cow Creek, with spring irrigation started. Ouray County, Colorado, May ©2022 hopkins/neoscenes.
The San Juan Mountains from CR-12, Cow Creek, with spring irrigation started. Ouray County, Colorado, May ©2022 hopkins/neoscenes.