Sunday, March 25, 2018

Geology of Leonardo’s Virgin of the Rocks

By Steven Wade Veatch

Leonardo da Vinci (1452-1519), considered to be one of the greatest painters of all time, used his knowledge of geology to inform his art. Leonardo was also noted for his work in sculpture, anatomy, mathematics, architecture, and engineering during the Italian Renaissance (about 1330 to 1450).

Leonardo da Vinci’s Virgin of the Rocks (1483-1486). From his studies of geology, he learned how the Earth works and improved the realism of his paintings. Location: Louvre, Paris. Oil on panel transferred to canvas. Height: 199 cm (78.3 in). Width: 122 cm (48 in). Image is in the public domain.
From a geological perspective, Leonardo da Vinci’s paintings present a realistic portrayal of nature.  In his Virgin of the Rocks (1483-1486), on display in the Louvre in Paris, the geological accuracy is striking (Pizzorusso, 1996). The painting’s subject is both the Virgin and the rocks. The Virgin sits in front of a grotto or cave. Various aspects of the grotto, according to geologist Ann Pizzorusso (1996), “are rendered with astounding geological accuracy. Leonardo has painted a rich earthscape of rock eroded and sculpted by the active geological forces of wind and water. Most of the rock formations . . . are weathered sandstone, a sedimentary rock.” What looks like basalt, an extrusive igneous rock formed by the cooling of lava, appears above Mary’s head and at the top right of the picture. Leonardo even painted the columnar joints formed by the cooling of the rocks. Also, just above her head is a precisely painted seam between the sandstone and igneous formations, and a joint runs horizontally to the right of her head. Art historians believe that the landscape in this painting is not an actual place, but one conjured up by Leonardo’s experience, understanding of geology, and observation (Issacson, 2017).

A second version of the painting, also called the Virgin of the Rocks (1495-1508), is exhibited in the National Gallery in London. This painting fails to depict such a faithful rendering of geology as the one in Paris. Despite decades of analysis by scholars, there are doubts that it is an authentic da Vinci painting, but rather a copy of the original painting by another artist.

Leonardo da Vinci was ahead of his time in his understanding of geology, and he meticulously recorded his observations in notebooks and journals (Bressan, 2014). After his death, his notebooks ended up on the bookshelves in libraries and private collections throughout Europe, while other notebooks disappeared into history (Waggoner, 1996).

Da Vinci wrote in one of his notebooks, the Codex Leicester, about the fossils he found as he walked the countryside. Da Vinci recognized that fossils were the remains of once-living organisms and relics of former times and other worlds—traces of a past hidden to other thinkers of the time. Da Vinci also observed that distinct layers of rocks and fossils covered large areas, and the layers were formed at separate times—not in the single biblical flood (Issacson, 2017). And centuries before Darwin, Leonardo conjectured through his understanding of rocks, fossils, and the slow processes of erosion and deposition that the world is much older than what church fathers proclaimed (Jones, 2011).

Leonardo da Vinci’s observations of fossils found on the tops of mountains wore a path through his thoughts. Since fossils are found in the mountains, the surface of the Earth, Leonardo posited, has changed over time. For example, an ancient sea is now dry land (Jones, 2011).  Leonardo concluded that as mountains formed, they lifted marine sediments—carrying fossil-bearing rocks skyward to become mountain peaks. Today, geologists know that tectonic plates and other geological processes form mountains.

In another of his notebooks, the Codex Arundel, now housed in the British Library, Leonardo describes graded bedding in layers of sedimentary rocks (Pedretti, 1998). He also had a basic understanding of the superposition of rock strata, where the oldest rocks in a sequence of sedimentary rocks are at the bottom. This concept would not be recognized until the second half of the 17th century when Danish geologist Nicolas Steno, carrying the light of learning, took up the subject in 1669—laying the foundation for modern stratigraphy and geological mapping (Capra, 2013).

Da Vinci never published his theories. He only wrote his observations in his notebooks, which ended up scattered or lost. For more than three hundred years, his notes were not part of the progression of science. It was left for future scientists to rediscover Leonardo's observations on the vastness of geological time, sedimentary layering, and the significance of fossils, and to make these discoveries part of science.

Leonardo da Vinci’s endless curiosity and boundless creativity made him the quintessential Renaissance man. He was a keen observer of nature whose interest led him to paint nature not only beautifully, but accurately.

Works Cited
Bressan, D. (2014, April 17). The Renaissance's Contribution to Geology: Landscape Painting. Retrieved from Scientific American:

Capra, F. (2013). Learning from Leonardo: Decoding the Notebooks of a Genius. New York: Berrett-Koehler.

Issacson, W. (2017). Leonardo da Vinci. New York: Simon & Schuster.

Jones, J. (2011, November 23). Leonardo da Vinci's earth-shattering insights about geology. Retrieved from The Guadian:

Pedretti, C. (1998). Il Codice Arundel 263 nella British Library. Florence: Giunti.

Pizzorusso, A. (1996). Leonardo's Geology: the Authenticity of the Virgin of the Rocks. Leonardo, 440.

Waggoner, B. (1996, January 3). Leonardo DaVinci. Retrieved from University of California Musuem of Paleontology:

Wednesday, September 27, 2017


 By Steven Wade Veatch

With the suddenness of a rattlesnake’s strike, an enormous boulder of Pikes Peak Granite moved down one of the steep slopes of the lower part of Ute Pass, Colorado. As this rock—larger than a yellow school bus—traveled down the hill, it flattened the bushes growing in front of it, and left a trail of scraped ground behind it.

Figure 1. Gravity’s relentless force pulled this huge boulder
down the hill to its resting place near US Highway 24
between mile marker 295 and 296. This is a geohazard.
Photo © S. Veatch.
This giant rock, perched on a slope in Ute Pass along US Highway 24— between Manitou Springs and Green Mountain Falls—moved downslope from the pull of gravity in a type of erosion called mass wasting. When combined with the water of winter snow melt or rain that alters ground conditions, gravity can move rocks downhill—the steeper the slope, the faster the rocks and boulders move (McGeary, Brown, & Plummer, 1992).

During a recent summer, thunderstorms poured rain on the pass.  The slope where this boulder rested was saturated with water, making the ground a muddy, slippery mess. As the rain soaked into the soil, it filled pore spaces, which pushed apart individual grains in the soil—decreasing the resistance of the boulder to movement (Murck, Skinner, & Porter, 1997). Also, some of the grass was washed away by rivulets and rills running downslope, also adding to the conditions that mobilized the boulder.

One night when it was quiet, except for the rasp of a cricket and the passing of an occasional car on the highway, the force of gravity became greater than the resistance of the ground holding the immense boulder in place. Catching the sleeping birds in the pine trees off guard, the giant rock yielded to the endless pull of gravity and slid down the slope—a geological event that starts within the blink of an eye.

Figure 2. A once moving boulder left behind a trail and pushed up
loose gravel in front of it as it slid down the slope of Ute Pass.
Photo © S. Veatch.
This rapid movement of rocks is a geohazard that develops over time and locally impacts Ute Pass and Manitou Springs. Ute Pass and Manitou Springs are in the path of sliding and falling rocks. Work is ongoing to mitigate some of these hazards. Travelers going through Ute Pass not only have to watch other drivers, but must also look out for moving boulders.

McGeary, D., Brown, W. C., & Plummer, C. C. (1992). Physical Science: Earth Revealed. Dubuque: William C. Brown.

Murck, B. W., Skinner, B. J., & Porter, S. C. (1997). Dangerous Earth: An Introduction to Geologic Hazards. New York: John Wiley & Sons, Inc.

Thursday, August 10, 2017


By Steven Wade Veatch

The tall spires and monoliths of the Garden of the Gods have been a landmark to countless travelers and explorers.  The story of these rocks starts long ago and spans many periods of geologic time. About 65 million years ago, forces in the Earth’s crust resulted in the uplift of buried Pikes Peak granite and the bending and warping of overlying sedimentary rocks to a near vertical position.  This uplift, called the Laramide Orogeny, formed a major fault, the Rampart Fault, that fractured rocks in the area and caused their movement along this and other faults.   

A view of the Garden of the Gods. Pikes Peak is in the background. 
South Gateway Rock (left) and North Gateway Rock (right) are 
eroded features of the Lyons Sandstone. A Ute encampment 
is seen at the base of North Gateway Rock. 
Antique postcard from the S.W. Veatch collection.
The Rampart Fault divides the Garden of the Gods Park. Rocks on the west side of the park are at an angle of 45 degrees or less. It is here that the rocks of the Fountain Formation, such as Balanced Rock, are on display. To the west were the Ancestral Rocky Mountains, formed 300 million years ago. Erosion washed down unsorted sand and pebbles of many sizes from the nearby Ancestral Rocky Mountains. By 250 million years ago these mountains were eroded away, leaving behind sediments piled up as gravels in layers that formed the Fountain Formation.  This rock unit, up to 4,500 feet thick, has a dark red color from the chemical alteration of iron minerals.  

Rocks of the Fountain Formation are on the west side
of the Garden of the Gods park. Balanced Rock is on
the left, Steamboat Rock is on the right. These landmark
conglomerate rocks reveal the interbedded nature of
the Fountain Formation.  Antique postcard from the
S.W. Veatch collection.
Rocks east of the Rampart fault have been tilted more than 90 degrees from their original, horizontal position, such as the North Gateway Rock, which is formed from ancient sand dunes when the area was much drier and windier 280 million years ago when all the continents were joined into one giant landmass known as Pangaea.  Today, geologists call this rock formation the Lyons Sandstone which is composed of uniform sized grains of sand. The Lyons Sandstone was deposited largely in a desert environment, and oxidation of iron to hematite caused the red color. 

Archaeologists tell us people have visited the Garden of the Gods for over 3,000 years.  Before the advent of settlers and their occupation, the plentiful game, wild plants, and nearby water, made the park a good camping site for the Ute people and other Indian tribes. 
Starting in the 1800s, explorers spread the word of the scenic wonders there. The 1850s and 1860s brought gold prospectors through the region and others who stayed and farmed and raised cattle in this area.  With the establishment of the railroad in the 1870s, tourists flocked to see the unusual sandstone formations. 

In 1879, General William Jackson Palmer, the founder of Colorado Springs, persuaded his friend, Charles Elliot Perkins, to buy land in Garden of the Gods.  Perkins paid $22.00 per acre for 480 acres that surrounded the Gateway Rocks.  Perkins, who lived in Iowa, was the president of the Chicago, Burlington and Quincy Railroad.  He never built on his land in Garden of the Gods and wanted his holdings to become a public park. Perkins died before this could be arranged.  In accordance with their father’s wishes, Perkins’ children offered the land to the City of Colorado Springs with the following restrictions: 1) the park will be free of charge to visitors; 2) the park will be known as Garden of the Gods; 3) no liquors could be made or sold in the park; and 4) no buildings could be built, other than those needed to maintain the park. 

Late in 1909, the Colorado Springs City Council accepted the land and conditions.  Today, Garden of the Gods Park, with over 1,360 acres, is a national landmark (designated in 1972 by the U.S. Department of the Interior) and a popular destination for tourists from all over the world. We all owe a debt to the Perkins family.

Monday, May 22, 2017

Fun with the Short Line’s Push Cars

Steven Wade Veatch and Peter Doolittle

The narrow-gauge Colorado Springs and Cripple Creek District Railroad, or Short Line, was built along what is now the Gold Camp Road. By 1901, the train ran all the way from Colorado Springs to Cripple Creek. This was the shortest route from the goldfields to Colorado Springs. Train cars, filled with gold ore, rumbled along the rails behind powerful steam locomotives to mills on the west side of Colorado Springs. The route also operated two daily passenger trains that provided service each way.

Figure 1 is an antique postcard that shows what is known as a "gravity car" that was popular with tourists, photographers, and other interested people from the Pikes Peak region who took a trip on these gravity cars that rolled down the grade at fast speeds from a point known as the “Summit” eastward to Colorado Springs.

Figure 1. This photo shows two tourists riding down a grade of the 
Colorado Springs and Cripple Creek Railroad on a gravity car. 
This photo is on a postcard.  From the S. W. Veatch collection.

These gravity cars could reach speeds of 40 MPH! What a thrill that must have been in these early days. This car appears to a lever operated handbrake. The location depicted in the postcard is Point Sublime on the Short Line. The lake in the distance is at the Broadmoor Casino, now the Broadmoor Hotel.

The white post in this picture is most likely a warning for a crew operating a flanger, or snow plow, that there is a bridge or tunnel ahead. There is probably some structure or obstruction out of view to the left in the postcard. Note the guard rails between the two outer rails going to the left. Those are usually present on a bridge or trestle, possibly a tunnel, to keep derailed equipment from falling off into the abyss or causing damage to the structure being protected. 

This so-called gravity car was known as a push or hand car and was used by section men or "gandy dancers" who were responsible for inspecting and maintaining a section of the railroad track. The gandy dancers used the push cars to get to and from the section they were working on that day. Push cars were a more primitive version of the pump handle handcar depicted in old movies. Someone, standing on the deck of these cars, would push them along on flat or level track by using a pole they pushed against the ground. In the case of mountain railroads, such as the Cripple Creek railroads, the push cars would be lashed onto the back of a train going upgrade and then allowed to coast down from the top of the pass or grade, carrying a gandy dancer along his section of track.

Friday, May 12, 2017

A Small White Dot

Steven Wade Veatch
Vishwam Sankaran

“There’s nothing new under the sun” goes a famous saying, and these words are very apt when trying to understand Earth’s climate trends. Thanks to numerous discoveries made about Earth’s ancient past, we now know that our climate has never been static. According to geological and paleontological records, climate change has affected the Earth throughout geologic time.

To understand climate change, researchers study past climates and events that affect climates such as volcanic activity, solar radiation, sunspot activity, astronomical changes, and other factors that influence climate. Once we understand the dominoes that have fallen during the past climate change events, we can understand and predict—to some degree—the kind of patterns that may follow current trends. To do this, scientists piece together clues from past climates provided by rock formations. Scientists likewise examine fossil records that yield climate signals from the past. These fossils range from prehistoric pollen to dinosaurs. Putting both geological and fossil records together reconstructs ancient climates and environments. More recent climate change is studied through climate records held in polar ice caps and ice sheets, ice cores, glaciers, isotopes of elements (like oxygen, carbon, and sulfur), soil sediments, and tree rings.

When we think of the term “ice age,” the picture that immediately comes to mind is early Neanderthals or Homo sapiens wrapped in animal fur, hiking endlessly through snow and ice-covered plains, striking fire, hunting mammoths, and surviving in nomadic camps. This image stems from the most recent ice age (Pleistocene Epoch), and evidence reveals more severe ice ages before the last one. Scientists know of at least five major glaciation events (see table 1). And it is speculated that some of the ice ages covered the whole Earth in snow and ice.

Table 1: Five Major Continental Glaciations. There have been five episodes of extensive continental glaciation through geologic time. The Cryogenian Glaciation lasted the longest, producing a “Snowball Earth” (Levin, 2013).
Time Period
Huronian Glaciation (Paleoproterozoic Era)
2.4-2.1 billion years ago
Cryogenian Glaciation (Neoproterozoic Era)
850-635 million years ago
Andean-Saharan Glaciation (Ordovician-Silurian Period)
460-430 million years ago
Karoo Glaciation (Carboniferous-Permian Period)
360-260 million years ago
Pleistocene Glaciation (Pleistocene Epoch)
2.6 million years ago to the present

Broadly speaking, a number of scientists believe Earth’s climate, throughout geologic time, can be characterized by three climate conditions. First, that of “Earth as a Greenhouse” when warm temperatures extend to the poles, eliminating the polar icecaps and all other ice sheets. The climate, in some parts of the planet, was like hell in a box. Secondly, that of “Earth as an Icehouse” which includes some permanent ice whose extent varies as glaciers periodically advance and retreat. And lastly, by what is termed as “Snowball Earth” where the planet’s entire surface is frozen up to hundreds of millions of years (Walker, 2003).

There is credible speculation that there is a fourth state: “Slush House Earth,” where there is an ice-free zone along the equator (Cowen, 2013). Today’s climate, marked by polar ice caps, is characterized by the second condition, an “Icehouse.” Since primordial times, it has been speculated that the Earth has been cycling between these phases.

The Earth froze completely in defiance to the warmth of the sun between 2.45 and 2.22 billion years ago (BYA), resulting in Earth’s first Ice Age, known as the Huronian Glaciation (named after Lake Huron in Ontario, Canada). This deep freeze may not have happened once, but perhaps several times, during the Huronian Glaciation (Levin, 2013).

The cause of this first Snowball Earth event is not known, however several theories have been proposed, including a decrease in solar output, the Earth passing through so-called space clouds, or an extreme cooling caused by a reduction in greenhouse gases ("Oceans of Ice: The Snowball Earth Theory of Global Glaciation," n.d.). Some scientists view a combination of these events could be a reason the Earth became frozen in ice. It seems likely that a sharp drop in carbon dioxide, a greenhouse gas, caused temperatures to plummet. An unimaginably thick, white ice sheet crept down from the poles. Snow, whipped by winds, danced on the crenelated surface of the ice while the bottom of the ice sheet plucked and ground the rock surface beneath as it crept forward.

During these frigid times sunlight, instead of warming the planet, bounced off the ever-spreading ice, in what scientists call the albedo effect, causing temperatures to fall—which created more ice—which bounced more sunlight back into the cold reaches of outer space (Melehzik, 2006). This process repeated in a positive feedback loop until the cooling became unstoppable: the ice marched on, temperatures plunged, and the blue planet became a small white dot—a snowball, surrounded by a riot of stars, orbiting the sun.

Of interest to scientists is that life came to a near biological standstill in the first Snowball Earth event, yet life survived this hyper-freeze phase. Even in an Earth almost entirely covered by ice, volcanoes punched through the ice by melting it. Against these odds and brutal mass extinctions, a handful of tiny organisms, living near volcanic vents on the sea floor, thrived. These organisms were anaerobic bacteria and called methanogens by scientists. The methanogens fed on mineral nutrients like sulfur, iron, and manganese from underwater volcanic vents and merrily expelled methane, a greenhouse gas. Oxygen was not present in the Earth’s atmosphere. The methanogens spread and continued to help gas-up an atmosphere that contained methane, nitrogen, and few other gasses in trace quantities. The microscopic methanogen’s methane trapped some of the sun’s energy and warmed the planet.

Following the Huronian Glaciation, the frozen planet thawed, marking one of the greatest periods of transition in our world’s history—The Great Oxygenation Event, one that would change forever the destiny of this planet we call home. Here is what happened.

Soon after Snowball Earth melted a new kind of bacteria evolved—cyanobacteria, the planet’s first photosynthesizing organisms that made oxygen (Canfield, 2016). There was a slow and episodic enrichment of gaseous oxygen in the atmosphere that continued over millions of years, possibly due to an exponential bloom of the cyanobacteria as mats that rolled and pitched with the waves of the sea.  Near the shore, cyanobacteria grew in layered structures known as stromatolites. Stromatolites were also present in some lakes and in any other shallow aquatic setting where the conditions were favorable.

FIGURE 1.  A photomicrograph of Cyanobacteria, Tolypothrix sp. Cyanobacteria produce oxygen as a by-product of photosynthesis, and it is thought this process converted Earth’s early, oxygen-poor, reducing atmosphere, into an oxidizing one, causing two major events: 1) the " Great Oxygenation Event” and 2) the so-called rusting of the Earth. Both events dramatically changed the nature of life forms on Earth and almost led to the extinction of anaerobic organisms. Image by Matthew Parker, used by permission under Community Commons Licence 3.0.

The rising oxygen levels brought the Great Oxygenation Event—a significant shift in the content of oxygen in the atmosphere (Crowell, 1999). As the cyanobacteria churned out more and more oxygen that bubbled through the water column, the methanogens almost went extinct—oxygen is toxic to them, those that survived lived in deep ocean water near hydrothermal vents and other places that protected them. In the meantime, due to the higher levels of oxygen resulting from photosynthesis, iron—previously dissolved in the oceans—could no longer stay in solution, leading to an intricate alchemy that brought the “Great Oxidation Event.”

This so-called “rusting” event formed rocks known as banded iron formations (BIFs). BIFs are white bands of chemically precipitated quartz, or chert, with alternating darker red bands of the iron oxide minerals hematite and magnetite. From this oxidation of iron and the formation of BIFs, we infer that oxygen began to appear in Earth’s atmosphere.

FIGURE 2. An exposure of banded iron formations (BIFs) at the Fortescue Falls, Dales Gorge, Karijini National Park, Western Australia. Cyanobacteria contributed oxygen to Earth’s atmosphere. This oxygen, combined with iron in the ocean’s water, caused chemical precipitation of iron oxides, and formed dark red bands that alternated with white bands of chert that produced the banded iron formations. Photo by Graeme Churchard, used by permission under Community Commons Licence 2.0.
Scientists continue to speculate on the source of the iron that was dissolved in the oceans prior to the Great Oxygenation Event. One source of the iron likely weathered from iron-bearing rocks on land masses. Another, much larger source of iron spewed out in dark clouds from more active submarine volcanoes and hydrothermal vents on the seafloor. 

The BIFs were deposited in a relatively brief geologic time between 2600 and 1800 million years ago, and occurred in great bodies that exceeded hundreds of meters in thickness and extended thousands of meters laterally (Macdougall, 2004). BIFs are an essential part of our modern industrial complex as they yield most of the rich iron ore mined today from the massive iron ore deposits of Minnesota, Michigan, Ukraine, Brazil, Labrador, and Australia (Levin, 2013).

Despite the frozen conditions of the first Snowball Earth, the period following it was an evolutionary triumph when oxygen became part of Earth’s atmosphere and early life flourished.  Oxygen formed the extensive iron ore deposits that are the foundation of modern society.  Although we are building a compendium of knowledge about past and present climate change, unanswered questions about Snowball Earth remain while certain aspects of climate change remain unknown. 
An army of scientists, with intellectual fire, continue their work in their search for answers. Even if we do not find some of these unknown factors affecting climate change, those factors will perhaps find us. 

References Cited

Canfield, D. (2016). Oxygen: A four billion year history. Princeton: Princeton                   Univ. Press.

Cowen, R. (2013). History of Life. Oxford: Wiley-Blackwell.

Crowell, J. C. (1999). Pre-Mesozoic Ice Ages: Their Bearing on Understanding the Climate System. Boulder: Geological Society of America.

Levin, R. (2013). The Earth Through Time. Hoboken: John Wiley and Sons.

Macdougal, D. (2004). Frozen Earth: The Once and Future Story of Ice Ages. Berkeley: University of California Press.

Melezhik, V. A. (2006). Multiple causes of Earth's earliest global glaciation. Terra Nova18(2), 130-137.

Oceans of Ice: The Snowball Earth Theory of Global Glaciation. (n.d.). Retrieved from

Walker, G. (2003). Snowball Earth: The Story of the Great Global Catastrophe that Spawned Life as We Know It. New York: Crown Publishers.

Tuesday, December 20, 2016

Notes on the Geology of Colorado Fishing

Steven Wade Veatch

A stream, as a geological agent, is one of the most powerful forces on Earth.  Many of Colorado's magnificent landscapes are the products of what streams do best—moving sediments sporadically downstream in regular cycles of erosion and deposition.  In Colorado, the Continental Divide splits streams that flow west to the Pacific Ocean from those that flow eastward to the Atlantic and the Gulf of Mexico. The sparkling streams of Colorado not only shape the landscape but also provide great fishing.  A deeper understanding of the riparian environment and geologic processes will enhance every fishing trip.

Snowmelt gives rise to Colorado's four major river systems:  the Platte, the Arkansas, the Rio Grande, and the Colorado.  Here is a quick review of those rivers.

The South Platte begins in the high country of South Park, but when it reaches the Cheesman Canyon, south of Deckers, local geology creates some remarkable places to fish.  Granite formed in the canyon under enormous pressure several kilometers below the surface and was later exposed by regional uplift.  With the erosion of the overlying rock, the granite expanded and cracked due to the release of pressure.  Gravity now causes the rock between the cracks in the granite to break loose in concentric slabs from the underlying granite body.  This process, exfoliation, results in the rounded nature of the granite outcrops in the canyon.

Granite boulders, slabs, and gravel form bars across the South Platte that dissipate the energy of the flow, producing areas of calm water and deep pools in Cheesman Canyon.  Willows grow along the banks while aspens and spruce trees grow tall, providing shade for brown trout.  Because browns are very selective in what they eat, they are hard to catch and grow to a large size.  Anglers on this river frequently use small flies, especially the pheasant-tail fly.

The Arkansas River starts in the mountains near Leadville and Tennessee Pass and flows south and east to merge with the Mississippi in the state of Arkansas.  After spring runoff has reworked sand and gravel bars, fresh gold placers can be panned on the upper reaches of the Arkansas.  As the Arkansas River flows by the Texas Creek recreation area on its way to the Royal Gorge, brown trout can be caught with caddis flies.  The Texas Creek area is also noted for deposits of rose quartz associated with pegmatite (coarsely crystalline) granite that intruded into metamorphic rocks.

The Rio Grande River has its headwaters in the San Juan Mountains and flows through New Mexico on its way to the Gulf of Mexico.  Near Creede, at Wagon Wheel Gap, the Rio Grande offers excellent fishing for browns, brooks, rainbows, and cutthroats using a prince nymph.  Cutthroat trout like slow pools that are just opposite large granite boulders.  There are several geothermal springs in the area, and excellent specimens of fluorite occur nearby.

The Colorado River drains the western slope of the Continental Divide and empties into the Gulf of California.  The major tributaries of the Colorado River are the San Juan, White, Yampa, and Gunnison Rivers.

The Gunnison River began downcutting into the Earth after a period of regional uplift 28 million years ago.  Today steep Precambrian gneiss (metamorphic rock) walls, with pink pegmatite dikes filling cracks and fissures, rise thousands of feet above the Gunnison River in the Black Canyon.  Geological processes here have produced the best fishing spot in the state.  It is the only place in Colorado where browns and rainbows grow to 16 inches in just four years.  Anglers in this area commonly use big nymphs.

A view of the Gunnison River running through 
the Black Canyon of the Gunnison. Photo used 
by permission under a Creative Commons License. 

Geologic processes have created 1,800 lakes above 9,000 feet in elevation in Colorado.  Many of these high-country lakes, called tarns, occupy the bottoms of amphitheater-shaped cirques where glaciers eroded into the mountain.  If there are enough insects to eat and the lake is deep enough for the fish to winter, there will be a population of trout.

Maroon Lake, at the foot of snow-striped Maroon Bells, 
is one of many Colorado lakes where great fishing awaits.  
Photo © S. W. Veatch.

Trout are not always easy to catch in high lakes as they feed along the edges and can be easily spooked.  Brook trout—commonly found in high country lakes, beaver ponds, and small creeks—tend to be small because they reproduce rapidly and surpass their food supply.

Trout like to cruise most of the 11,300 miles of streams in Colorado, and if anglers consider the rock and understand the role that geology plays in fishing, they have an advantage for catching trout. It is “gneiss” to know that fishing and geology can't be taken for “granite.”

Saturday, November 19, 2016

Stegosaurus: Colorado’s State Fossil

By Destin Bogart, guest blogger

As the state dinosaur of Colorado and one of the most iconic members of Dinosauria, Stegosaurus has earned this spot due to its fascinating history and its large number of fossil remains that allow paleontologists to understand more about Stegosaurus than other dinosaur genera that have a more fragmentary fossil record.

The first remains of Stegosaurus were uncovered during a period in the late 1870s known as, “The Bone Wars,” which intensified the collection efforts between two rival paleontologists—Othniel Charles Marsh and Edward Drinker Cope. Marsh initially discovered Stegosaurus in 1877 near Morrison, Colorado. Marsh first thought those remains belonged to a turtle-like animal, but soon revised this finding as more Stegosaurus fossils were unearthed.

O.C. Marsh's 1891 illustration of Stegosaurus ungulatus
Paleontologists now place the arrangement of the back 
plates in two alternating rows and oriented vertically. 
Copyright: public domain.
The largest Stegosaurus could stand four meters (12 feet) high at the tallest back plate and could reach lengths of up to nine meters (~30 feet). But the size alone is not what sets Stegosaurus apart from the other animals it shared its ecosystem with; rather the plates that line the spine of Stegosaurus make this dinosaur recognizable to everyone. Yet the plates remain an enigma; paleontologists have put forth many theories regarding how the plates are positioned. When Othniel Marsh first found the remains, he thought the plates lay flat against the body like the armor of a Pangolin (looks like a scaly anteater).

Through the years, paleontologists have refined the theory regarding the exact configuration of these plates, which went from two lines of identical plates on the back, to one row of plates that alternate. Scientists now place the arrangement of the back plates in two alternating rows and oriented vertically.

Stegosaurus stenops from the Late Jurassic of North America, 
pencil drawing by Nobu Tamura. Copywrite: Image license through the 
courtesy of Creative Commons.
What these plates were used for is still up for debate and has remained so since the animal’s discovery. Robert Bakker, a world-renowned paleontologist and curator of the Houston Museum of Nature and Science, speculates the plates of Stegosaurus were the inside, or core, of a bigger plate made of keratinous material. Bakker also suggests these plates were semi-movable and the animal used them as a defense, splaying them out to the sides to deter predators from coming too close. Other scientists have claimed the back plates were used to attract a mate or to control body temperature.

Even if the plates of Stegosaurus were not used for defense, Stegosaurus carried with it four spike-like osteoderms (bone embedded in the skin) on the end of its tail. These spikes (informally called thagomizers) bent out to the sides and backward and were likely an incredible defense against many large predators of the Morrison Formation. 

In 2014, Robert Bakker found a large open hole in the lower-front portion of the pelvis of a mounted Allosaurus skeleton at the Glenrock Paleontological Museum. The hole fits the tail spike of a Stegosaurus. This is evidence of just how formidable the tail of a Stegosaurus was as a defensive weapon when it struck the crotch of an Allosaurus. Evidence suggests bacteria, broken bone, and other debris remained in the wound, causing an infection that eventually killed the animal. According to Robert Bakker, “A massive infection ate away a baseball-sized sector of the bone, probably this infection spread upwards into the soft tissue attached here, the thigh muscles and adjacent intestines and reproductive organs.” 

The brain of Stegosaurus, although not quite walnut-sized, was unusually small compared to its body mass. So far, Stegosaurs claims the smallest brain size to body mass of any other dinosaur. This small brain presented a problem—how could it survive without more intelligence? It seems the large plates on its back and the spikes of its thagomizer were keys to its survival against predators. Also, Stegosaurs behavior played a role. Paleontologist Matthew Mossbrucker discovered in 2007, footprints of adult, juvenile, and hatchling specimens in the Morrison Formation that suggest Stegosaurs stayed together in small groups, most likely for protection against predators. 

Stegosaurus is the rhinoceros of the Late Jurassic as it was both an herbivore and highly dangerous to anything it perceived as a threat. Stegosaurus died out near the end of the Jurassic, leaving only fossils and footprints as a reminder of its existence. However, paleontologists can, using fossils and a little bit of educated guesswork, begin to understand how this animal behaved, how it lived, and how it died.

Author’s Bio: Destin Bogart is 16 years old and ever since he can remember he has had a passion for paleontology. He is an Earth Science Scholar with the Colorado Springs Mineralogical Society and is a junior IB World Student at Pueblo West High School. Destin is planning a career in vertebrate paleobiology.


Castro, Joseph. "Stegosaurus: Bony Plates & Tiny Brain." LiveScience. Purch, 08 Dec. 2014. Web. 18 June 2015.

Holtz, Thomas R. Jr. (2012) Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages, Winter 2011 Appendix.

Lambert, D (1993). The Ultimate Dinosaur Book. Dorling Kindersley, New York. pp. 110–29. ISBN 1-56458-304-X.

Carpenter, K (1998). "Armor of Stegosaurus stenops, and the taphonomic history of a new specimen from Garden Park Colorado". The Upper Jurassic Morrison Formation: An Interdisciplinary Study. Part 1. Modern Geol. 22. pp. 127–44.

Carpenter, K and Galton PM (2001). "Othniel Charles Marsh and the Eight-Spiked Stegosaurus". in Carpenter, Kenneth. The Armored Dinosaurs. Indiana University Press. pp. 76–102. ISBN 0-253-33964-

Pastino, Blake De. "Allosaurus Died from Stegosaur Spike to the Crotch, Wyoming Fossil Shows." Western Digs. Western Digs, 23 Oct. 2014. Web. 20 June 2015.
"Stegosaurus; Colorado State Fossil." State Symbols USA. STATE SYMBOLS USA, n.d. Web. 21 June 2015.

Jacobson, Rebecca. "First Steps of a Baby Stegosaurus, Captured in 3-D." PBS. PBS, 16 July 2014. Web. 22 June 2015.