June 2023 Outcrop

OUTCROP

Newsletter of the Rocky Mountain Association of Geologists

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OUTCROP

Newsletter of the Rocky Mountain Association of Geologists

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The Rocky Mountain Association of Geologists (RMAG) is a nonprofit organization whose purposes are to promote interest in geology and allied sciences and their practical application, to foster scientific research and to encourage fellowship and cooperation among its members. The Outcrop is a monthly publication of the RMAG.

2023 OFFICERS AND BOARD OF DIRECTORS RMAG STAFF

PRESIDENT Ben Burke bburke158@gmail.com

PRESIDENT-ELECT Mike Tischer mtischer@gmail.com

1st VICE PRESIDENT Ronald L. Parker parkero@gmail.com

1st VICE PRESIDENT-ELECT Lisa Wolff lwolff@bayless-cos.com

2nd VICE PRESIDENT Matt Bauer matthew.w.bauer.pg@gmail.com

2nd VICE PRESIDENT-ELECT

Jason Eleson jasoneleson3@gmail.com

SECRETARY Sandra Labrum slabrum@slb.com

TREASURER

Anna Phelps aphelps@sm-energy.com

TREASURER ELECT

Holly Lindsey holly@energyfunders.com

COUNSELOR

Steve Crouch scrouch@whiteeagleexploration.com

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The Outcrop is a monthly publication of the Rocky Mountain Association of Geologists

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F i e l d T r i p s

Field Trips Scheduled for 2023

April 2 1

June 4 - 8

CEMEX Quarry Tour

View the stratigraphy and sedimentology of the Niobrara/Fort Hays Formation at the CEMEX Quarry in Lyons. The quarry is undergoing reclamation, but many quarry faces are still accessible.

San Juan River Float Trip

5 days/4 nights on the Lower San Juan with Fort Lewis on the Water Float through goosenecks, visit dramatic geological and archaeological sites Registration open!

Paleozoic Impact Crater Field

June 2 42 5

July 1 5

Sept 9

On this unique field trip you'll see more impact craters in one day than anywhere else on Earth. Led by Kent Sundell, geology instructor at Casper College, who has studied and written extensively on this crater field, the Douglas Impact Site

Stories in Stone: The Rocks that Built Denver

A 2+ mile walking tour of some of downtown Denver’s iconic stone buildings, many of which are constructed with rock from Colorado quarries. See Yule Marble, Pike’s Peak and S. Beaver Creek Granites, and more! Refreshment stop is scheduled

Beulah Marble Quarry Tour

Tour of the historic Beulah Quarry, source of Colorado Capitol's most unique building stone, led by Quarry owner Ken Balleweg. Also included is a visit to the Steelworks Center of the West in Pueblo.

Geology of Golden Bike Ride

Sept 3 0

Grab your bike and join Dr Donna Anderson on a tour of the geology of the Golden area Trip is 9 miles on a bike path

Registration for trips will generally open one month before the trip date. Check www.rmag.org for updates and details.

Dates subject to change. View website for additional info.

OUTCROP

27 Outreach Event Volunteers Needed!

33 Join Our Mentorship Program

36 RMAG Foundation Announces Winners of the Neal J. Harr Memorial Award and the Brown Field Camp Scholarship

38 WANTED: Colorado Rocks!

COVER PHOTO

“Sunrise over the outcrop as seen near the trackways discussed in the lead article” –Anton F.-J. Wroblewski and Bonnie E.

Newsletter of the Rocky Mountain Association of Geologists

Gulas-Wroblewski

SUMMIT SPONSORSHIP

October 20, 2022

Geoscience Community:

We greatly appreciate every Summit Sponsor and Event Sponsor that has contributed to RMAG over the last year. We could not exist without your support.

In RMAG’s 100th year we have emerged from the global pandemic to return to many of RMAG’s beloved programs, and we created new programing to meet the needs of our members and the greater geoscience community. Monthly luncheons returned to in-person, with the addition live streaming. The 2022 Golf Tournament sold out bringing over 100 golfers out for a great afternoon together. The Powder River Basin Symposium offered two days of talks and core viewing to a packed room with attendees from across the country. Members young and old celebrated RMAG’s past and future at the 100th Anniversary Party. But that’s not all, the Diversity and Inclusion Committee in conjunction with Education Outreach attended numerous community outreach events from Girl Scout Days at Dinosaur Ridge to the Juneteenth Festival, sharing our members love of the geosciences with the next generation. Short courses were held both in person and online creating educational opportunities for members in Denver and across the country.

2023 brings new opportunities for RMAG. Your sponsorship dollars will help RMAG bring to fruition the 2023 North American Helium Symposium, an exciting Field Trip season, and a dynamic list of luncheon speakers on topics ranging from the state of the industry to the Williston Basin to geothermal energy storage. These dollars will allow RMAG Members to impact the next generation at outreach events throughout the community and provide opportunities for the geoscience community to connect and build their network. We’re looking forward to seeing everyone on a more regular basis.

Your sponsorship dollars support our excellent publications including the monthly Outcrop newsletter and the quarterly Mountain Geologist journal We recognize your financial commitment with in-person signage, website and publication advertising, as well and social media posts before each online event. With a LinkedIn group of almost 3000 members, we make our sponsors visible to the geoscience community for both virtual and in person events.

Thank you to those who are already a Summit Sponsor, we look forward to your continued support in 2023. If you are not already a sponsor, please look at the many complementary benefits included with the sponsorship levels. If our annual sponsorships don't make sense for your company, or you wish to sponsor something specific, ask about our single event sponsorship opportunities. Please feel free to contact our staff with questions by email: bcrowther@rmag.org or by phone at 720-672-9898 ext. 102.

We and the staff of RMAG thank you all for your continued support and look forward to seeing you in person this year.

Ben Burke

Bridget Crowther 2023 RMAG President RMAG Executive Director

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RMAG MAY 2023 BOARD OF DIRECTORS MEETING

By Sandra Labrum, Secretary slabrum@slb.com

Hi everyone! Happy start of summer, I hope that you all have fantastic summer vacation plans. Me personally, I will be in Oslo for the entire month of June! Fjords and glacial till here I come! If you are still looking to fill out your summer plans, please consider volunteering with RMAG. The D&I committee has several great volunteer opportunities in June that would love to have you. Reach out to Bridget for more information.

The May Board of Directors meeting took place May 16th, 2023, at 4:15pm online. All board members were present. The Finance committee started off the meeting with an overview of the financial standing in April. Thanks to the investment account April ended net positive.

The Continuing Education Committee is continuing to host hybrid lunches with great success. Emilie Gentry will be presenting in June, The Role of Fractures and Fault Zones on Exploration and Development of Geothermal Reservoirs. The Membership committee is now accepting applications for the mentorship program so

Publish with…

be sure to apply to be either a mentor or mentee. We are also continuing to host monthly events. June women’s coffee will be on June 6th at Vibe Coffee sponsored by White Eagle Exploration. The monthly happy hour will be near the end of June. The Publications Committee is still hard at work making sure there is high quality content for both the Outcrop and the Mountain Geologist. The Educational Outreach committee has a full schedule of events for this year. All the events that they participate in have been very successful and inspire a love of geology in kids. On the Rocks, has a full slate of great field trips planned this year. Registration is open for most so sign up today! Finally, Diversity and Inclusion committee has been hard at work bringing you member corners in each Outcrop as well as cohosting the women’s group coffee. The committee is actively looking for volunteers for Juneteenth, and PrideFest so sign up today!

I hope you all have a fantastic June. Until next time!

Expanded geologic focus:

• Entire greater Rocky Mountain area of North America

• West Texas and New Mexico to northern British Columbia

• Great Plains and Mid-Continent region

Why contribute?

• Reach a broad industry and academic audience

• Quarterly peer-reviewed journal

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• Every subdiscipline in the geosciences

Email: mgeditor@rmag.org

https://www.rmag.org/publications/the-mountain-geologist/

PRESIDENT’S LETTER

By Ben Burke

Geothermal Energy

This month, my focus is on geothermal, not just because of the June 7th monthly luncheon talk by Emilie Gentry on the application of fracture analysis to geothermal exploration, but because I work in the geothermal industry. As geoscientists, we know that the Earth is a dynamic and complex system, and that the energy resources it provides are critical to our modern way of life. While much attention has been paid to traditional oil and gas reserves, it is important to also consider the potential of geothermal energy as a sustainable and renewable energy source.

Geothermal energy harnesses the heat from the Earth’s interior to generate electricity and heat buildings. It is a clean and reliable source of energy that has the potential to play an increasingly important role in meeting our energy needs. The Rocky Mountain region is particularly well-suited for geothermal energy production, with its high levels of geothermal activity and extensive oil and gas infrastructure.

As geoscientists, we are uniquely positioned to understand the geological processes that drive geothermal activity and to explore the potential for geothermal energy production. Geothermal power generation has been going on at The Geysers in California since the late 1950s generating up to 800 megawatts of baseload power. Modern technological advances

allow fluids as cool as 150° F with as little as 900 barrels a day of flow to be useful for kilowatt-scale power generation.

At the same time, it is important to consider the relationship between geothermal energy and traditional oil and gas geoscience. While these resources may seem to be at odds, they are actually complementary. Many oil and gas fields are located in areas with high geothermal activity, such as the Raton Basin of Colorado, the hottest basin in the state. The expertise and infrastructure developed for oil and gas exploration and production can be leveraged for geothermal projects. Furthermore, the use of geothermal energy can reduce the carbon footprint of oil and gas production by providing a clean and renewable source of power for drilling and extraction operations.

As geoscientists, we have a responsibility to explore the potential of all energy resources, including geothermal, in a sustainable and responsible way. By leveraging our expertise and working collaboratively with other industries and stakeholders, we can ensure that the energy needs of our society are met while minimizing the impact on the environment.

As always, I urge you to attend RMAG events and get involved in your society. Enjoy the beginning of summer!

F i e l d T r i p s

P a l e o z o i c I m p a c t

C r a t e r F i e l d

J u n e 2 4 - 2 5 , 2 0 2 3

D o u g l a s , W y o m i n g

S e e m o r e i m p a c t c r a t e r s

t h a n a n y w h e r e e l s e o n

E a r t h ! D o n ' t m i s s t h i s

u n i q u e f i e l d t r i p l e d b y D r .

K e n t S u n d e l l .

STORIES FROM THE SEASHORE

Exploring A 59-Million-Year-Old Coast On Wyoming’s High Plains

By Anton F.-J. Wroblewski and Bonnie E. Gulas-Wroblewski

HUMID, SALTY FOG HANGS SOGGY

over a coastal lagoon as the tide retreats towards the inland sea’s depths. Flurries of wading birds shimmer across the freshly-exposed muddy flats, frantically probing for holed-up invertebrate delicacies. Hulking mammals plod with implausible grace across the tidal flats, spooking crocodiles into foot-propelled retreats along the bottoms of freshwater channels. The sticky air is full of buzzing, whirling, and darting insects that pause only long enough to daintily deposit their eggs into the languid freshwater of tidal marshes and creeks. The scene, rife with the pulse of ecological drama and dynamism, is south-central Wyoming, 59 million years ago. These ephemeral moments in time are captured not by bones, teeth, shells, or other body fossils but by more subtle clues imprinted in the rock record.

The modern high plains of south-central Wyoming’s Hanna Basin might appear barren on first impression (Figure 1), but it’s amazing what reveals itself when you just take a look around. Walking across the wind-blown, sagebrush flats northwest of Medicine Bow, you’ll see enormous, white windmills, skittish pronghorns, a variety of songbirds and raptors,

snow-capped mountain ranges rising in the distance, and low-lying, rust-colored sandstone ridges streaking across the grasslands. For years, we, and many other paleontologists, have wandered these ridges, searching for evidence of past life in the form of fossilized bones, teeth, shell, and even soft parts like skin impressions. Until recently, we all missed the bigger, more vibrant picture of an ancient world hidden in plain sight. We were seeking remnants of dead things when all around us, preserved over countless eons, there were echoes of living, breathing, active animals preserved in the rock. Only after submerging ourselves in the study of trace fossils (i.e., ichnofossils) were we able to recognize these silent witnesses to brief moments from days long past.

Unlike body fossils that constitute the physical remains of dead organisms, trace fossils record the interaction of living organisms and the substrate. Ichnofossils capture the everyday bustle of a rich ecosystem: animals walking, swimming, digging, nesting, feeding, resting, and even pooping as plants extend roots below the surface in search of stability and nutrients. Unfortunately, trace fossils are not as glamorous as body fossils to most of the public, or even most earth

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FIGURE 1: Location map of the Hanna Basin area with red star marking the tracksite. Photographs of Anton’s truck camper near the tracksite, and Bonnie at a campsite with the view to the south, showing Elk Mountain in the distance.

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scientists. After all, when’s the last time a fossil burrow or petrified puke was auctioned off by Christie’s for tens of millions of dollars? While not as visually titillating as a creatively-mounted Tyrannosaurus rex skeleton, trace fossils offer unparalleled glimpses into past ecosystems and behaviors as well as valuable information on the ambient physicochemical environment during the time of their making (Ekdale et al., 1984; Curran, 1985; Buatois and Mángano, 2011). Ichnofossils have been used for decades by the energy industry to refine paleogeographic maps of ancient seaways and landscapes and continue to be studied in both the modern and ancient world. Trace fossils can even set back the earliest known date for the origin of various branchings of the tree of life (Wroblewski and Gulas-Wroblewski, 2022). Despite the invaluable and diverse insights we can glean from the study of ichnology, the field continues to be viewed as something arcane and shrouded in mystery by most paleontologists and sedimentologists. Few universities offer courses in ichnology and, in today’s high-tech, data-science-obsessed world of field geology, even fewer students are taught of this low-tech method’s potential to unravel mysteries that can’t be answered by drones or video game-like outcrop models souped up by AI.

In the dusty outcrops of the Paleocene (63-55 Ma) Hanna Formation, trace fossils revealed an unexpected glimpse into coastal plain and lagoon environments that were previously thought to have disappeared with the dinosaurs (Wroblewski and Gulas-Wroblewski, 2021; Wroblewski and Steel, 2022). A plethora of burrows, trails, tracks, and swim traces paint a vivid picture of a previously unknown, thriving coastal ecosystem. The first hints of this seaside world came in 2016 when on a trip to a friend’s dinosaur-themed wedding in Lusk, we discovered natural casts of sea anemone resting traces during a side visit to the outcrop (Figure 2). Siphon traces left by marine clams accompanied the anemone traces and dimpled the top of a meter-thick sandstone body that had accumulated on carbonaceous shale and coal. These strata represent a marine transgression into a coastal coal swamp, just as we see today in the modern Mississippi River delta when subsidence outstrips sediment supply. The scientific consensus had up to this time been unanimous (a rare instance of agreement in the geological

community) that by the late Paleocene, southern Wyoming was nowhere near the sea. Countless papers, articles, and conference presentations repeated the mantra that coal swamps and riverine floodplains dominated the landscape (Blackstone, 1975; Lillegraven and Ostresh, 1990; Flores et al., 1999; Hajek et al., 2012; Dechesne et al., 2020). Although reports of tidal deposits and marine trace fossils in the early Paleocene (approximately 65 million years ago) indicated that there was at least some connection to the Western Interior Sea (aka. the Cannonball Sea), by 6 million years later in the late Paleocene, this region was supposedly a fully terrestrial environment hundreds of miles from the closest shoreline (Wroblewski and Steel, 2023). How then did these irrefutably marine trace fossils fit into the picture?

Three years passed as we pondered this seemingly irreconcilable situation while work and other commitments diverted our main attention to other topics. In the fall of 2019, Anton was lucky enough to find himself travelling between Salt Lake City and Cheyenne, enroute to the annual meeting of the Rocky Mountain Section of AAPG. This provided an excuse for a quick trip to the Hanna Formation to revisit the marine mystery traces and to try to make some sense of them. While walking towards the first outcrop, more anemone traces were immediately visible (Figure 3). Insect burrows were mixed into the assemblage, indicating brackish rather than fully marine water. How had he missed these important fossils in all the years he’d been visiting these rocks? From the summer of 1991 until 2001, Anton had worn through countless hiking boots exploring this area, first while working as an undergraduate field assistant and later on his PhD thesis. Although he’d noticed some of the odd shapes and outlines, he’d never recognized their monumental importance. However, nearly two decades of work in the energy industry provided a golden opportunity to study trace fossils in a kaleidoscope of modern and ancient depositional settings, and now he recognized them for what they were. After taking copious notes in his field notebook and photo-documenting the intriguing finds, Anton began walking towards the next ridge over, stratigraphically below the one he was on. It was here that the largest assemblage of Paleocene mammal tracks anywhere in the world stretched out

FIGURE 2: Map showing the extent of the Western Interior Seaway approximately 59 million years ago based on ichnological evidence from the study area (red star). Marine trace fossil specimens photographed in 2016 represent sea anemones and marine bivalves.

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before him.

16

The near-vertical sandstone fin rose up above the badlands below, while the grassy, sagebrush plains rolled into the distance behind. The morning sun struck the surface just right, and some apparently irregular depressions and dents in the bedding plane coalesced into three discrete trails with the unmistakable regularity of footsteps (Figure 4). Excitement and panic set in all at once. There were only three other Paleocene mammal trackways reported in the world at that point. Two short ones, made by raccoon- and bear-sized animals in Alberta, Canada, and longer one made by bear-like pantodonts called Titanoides in the ancient coastal coal swamps of what is now Svalbard, Norway (Lüthje et al., 2010; Wroblewski and Gulas-Wroblewski, 2021). The trackways preserved on the slab of sandstone before him were much longer than any of these previously-described trails though. The individual tracks had four or five blunt toes and broad outlines, bringing to mind those made by Nile hippos.

Over the next three summers, detailed mapping, exploring, and measuring of the sedimentary bodies hosting the trackways brought to light at least five

individual track-bearing horizons winding over more than half a mile (1 km) along a northwest-southeast transect. Thousands of tracks are preserved as natural casts, original impressions, and under-tracks (beds of sediment deformed downward by tracks made on younger beds or their upper surfaces). Some of these tracks preserve evidence of the animal’s foot dynamics during the walking cycle, while others demonstrate the enormous weight of the trackmakers (Figure 5). Nowhere on Earth is such a diversity of Paleocene mammal tracks preserved. This seemingly barren site tucked away in the badland-scarred grasslands of south-central Wyoming is truly one of a kind.

FIGURE 3: Anton pointing to natural casts of sea anemone traces found in 2019. Possibly mayfly burrows (Fuersichnus) are also present in this bed.

FIGURE 4: Photographs and interpretive drawing of the original tracks found in 2019. The white material is biodegradable baking flower.

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The Hanna Formation trackmakers frequented emergent or semi-emergent tidal flats, and their tracks are preserved on the tops of sandstone beds that contain anemone burrow casts on their undersides. These animals were at home in coastal lagoons and tidal flats. Large and small tracks occur alongside each other suggesting adults and juveniles walking side by side and providing a rare glimpse into the possible family dynamics of these long-gone creatures.

In addition to these blunt-toed tracks, prints preserving the marks of heavy claws contribute to parts of the uppermost trackway (Figure 6), confirming the presence of another five-toed trackmaker. The most likely suspect is the bear-like pantodont Titanoides, whose fossil bones have been recovered from deposits of the same age in the Bighorn Basin of Wyoming (Gingerich, 1996). Resembling a modern grizzly bear in size and morphology, with sharp incisors and canines and stocky limbs, Titanoides’s use of wet habitats has previously been demonstrated by its tracks in the coal swamp deposits of Svalbard, Norway (Lüthje et al., 2010). Like modern bears, Titanoides probably roamed far and wide in search of food, opportunistically partaking in the coastal buffet provided by tidal flat residents (clams, fish, Coryphodon, etc.) and all sorts of exotic seafood that washed up with the tides

and storms.

Smaller, four-toed tracks are less common than the larger, five-toed specimens and may represent the earliest record of artiodactyls or tapiroids (Wroblewski and Gulas-Wroblewski, 2021). Neither mammalian group is known from skeletal remains earlier than the Eocene, but it has been suggested that both had origins in the Paleocene or even Cretaceous, a deep history supported by these tracks (Halliday et al., 2017; Zurano et al., 2019; Wroblewski and Gulas-Wroblewski, 2021). Without skeletal remains to associate with definitive tracks, the identity of these trackmakers will remain controversial and uncertain. However, their presence is intriguing and serves as a reminder of how little we actually know about the early evolution of modern mammalian lineages and how much remains to be discovered.

The more we looked, the more the ancient seaside ecosystem revealed itself. At least two species of ancient wading birds are represented by tracks and probe feeding traces (Figure 7). Avian probe feeding behavior has been described as far back as the Cretaceous and in the Eocene (Falk et al., 2010; Lockley et al., 2020), but this is the first record of this specialized foraging method from the Paleocene and, therefore, fills in an important gap in the fossil record of bird

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FIGURE 5: Examples of a track preserved in cross-sectional view with trackmaker walking right to left and under-tracks (represented by arrows).

MONTHLY HAPPY HOUR

G r a b a d r i n k w i t h y o u r f e l l o w G e o s c i e n t i s t

c o l l e a g u e s a n d f r i e n d s a t o n e o f o u r

m o n t h l y h a p p y h o u r s ! W e g e t t o g e t h e r a t a

d i f f e r e n t l o c a t i o n e a c h m o n t h , s o c h e c k

o u r w e b s i t e f o r d e t a i l s . w w w . r m a g . o r g

U P C O M I N G R M A G H A P P Y H O U R S

J u n e 2 3 r d

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A u g u s t 2 5 t h

S e p t e m b e r 2 8 t h

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behavior. Based on comparisons to plaster casts of modern wading bird tracks, we deduce that these Paleocene probe-feeders were the size of willets (smaller species) and sandhill cranes (larger species). Judging from the foraging preferences of their modern counterparts, these extinct waders most likely dined on the abundant polychaete worms, small crustaceans, and insects that called the Paleocene tidal flats home. However, this smorgasbord was not without its risks for the waders. Crocodilians also stalked these coastal habitats in search of a tasty seaside meal. Although the

crocs left no skeletal or dental remains to mark their presence, elongated grooves preserved at the bases of distributary channel bodies serve as ghostly records of their clawed toes sweeping along the bottom as they swam (Figure 7)

While tracking is deeply ingrained in our hominid evolutionary roots (Liebenberg, 1990), our natural ichnological skills are now augmented by rapidly developing technology that takes advantage of the latest in LiDAR and photogrammetry. Not too long ago, we depended on perfect lighting to cast shadows that

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FIGURE 6: Photograph and digital elevation map of a heavily clawed track that might have been made by Titanoides. Forefoot and skeleton of Titanoides with missing bones reconstructed in grey.

S t o r i e s i n S t o n e : T h e R o c k s T h a t B u i l t D e n v e r

J u l y 1 5 , 2 0 2 3 R o c k y M o u n t a i n A s s o c i a t i o n o f G e o l o g i s t s

T a k e a w a l k i n g t o u r w i t h R M A G & l e a r n a b o u t D e n v e r ' s i c o n i c s t o n e b u i l d i n g s a n d t h e g e o l o g y o f t h e q u a r r i e s w h e r e t h e s e u n i q u e r o c k s w e r e e x t r a c t e d .

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enhanced the vagaries of slight indentations to form a close approximation of a clear print for photography. Today, using mobile phones the size of a pocket calculator, we can gather digital images that can be reconstructed into 3-dimensional models, rendered as color-coded elevation (or “heat”) maps, and even used to make perfect 3D prints from resin and polymers (Figure 7). These advancements replace the potentially destructive methods of yesteryear, which required tedious brushing of thin layers of liquid latex onto the track surfaces, waiting for hours as it cured, and then encasing the whole in a plastic mother mold to retain its shape after the latex had been pulled out. Now, regardless of lighting conditions, climate, or time limitations, data can be painlessly gathered in a non-destructive way in seconds instead of hours, days, or even weeks. Boosted by these game-changing technological tools, our work continues with new efforts focused on digitally capturing all of the exposed surface tracks and as many of the tracks preserved in cross-section as possible before these snapshots of the Paleocene erode, unceremoniously crumbling down the hillside and taking their secrets of the past with them.

Compiling all of our observations, measurements, maps, and comparisons to modern traces and trace makers, we have been able to come to some revealing conclusions. Approximately 59 million years ago, tectonic subsidence rates were extremely high in south-central Wyoming. Rivers delivered huge volumes of sediment from the surrounding uplifts, but these deposits could not keep up with the sinking, resulting in the nearby Western Interior Seaway flooding back into the area that is now the modern Hanna and Carbon basins as it had in the Cretaceous (Wroblewski and Steel, 2022). The newly flooded wetlands served as novel habitats for the local aquatic and terrestrial animals to colonize. Freshwater or brackish-water insects could live alongside marine anemones in bayhead deltas and distributary channels in what we call “the Goldilocks zone”, meaning it’s not too salty for freshwater organisms and not too fresh to eliminate all marine creatures. This was the setting in which the large mammals and probing birds left their marks.

In the distance, trees line a shoreline that marks the spot where forested, swampy land meets brackish

water bay. Further off, the hazy purple outline of a low range of hills and highlands is barely discernable, though these uplifts are the source of the small streams and rivers that flow into the coastal lagoon below. Crocodiles glide through the freshwater and brackish channels, avoiding the salty waters of the lagoon. The constant rumble of breakers crashing against a barrier island to the east is like the roar of an oncoming train, but the calm of the lagoon’s water is only broken rarely by a breeze riffling across its surface or the rare storm that churns it into a roiling, grey-green cauldron. Wading birds resembling modern willets and sandhill cranes stride across the expanding tidal flats, displaying to each other, calling, and probing for invertebrates as swarms of biting insects rise up with a high-pitched whine every time the breeze dies down. The falling tide exposes anemones to the air, spurring them to retract squirming tentacles back into their barrel-shaped bodies and retreat into the silt to patiently wait for the next high tide. Distinct sounds of heavy feet splashing, squishing, and sucking out of the sand and mud are punctuated by snorts, rumbling growls, and the occasional sneeze. A group of cow-sized mammals, seemingly a cross between river hippos and brown bears, is schnuffling for edible debris washed up by the previous night’s storm. Adults and some half-grown juveniles, born earlier in the spring and now enjoying their first summer trip to the seaside, traverse a path that they will use for years to come. They crave the salt and other essential minerals that the plants they normally browse upon do not provide. Some wade into water deep enough to cover all but the tops of their heads to escape the relentless heat and blood-sucking insects. A bear-like mammal, the same size as the largest of the hippo imposters, lumbers along the tidal flat, stopping to sniff at bits of flotsam that have washed up with the last high tide. These denizens of the coast have no way of knowing that their activities will be preserved for the next 59 million years in the sediment below their massive, clawed and hoofed feet. They can’t conceive of our human-saturated future and will never know a world other than this coastal paradise. When their lives end, their bodies will be completely returned to the earth, leaving no evidence of their existence. It will be the descendants of the small, squirrel-like

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FIGURE 7: Bird and crocodilian traces from the Hanna Formation. White arrows pointing to probe marks made by the bill as the bird was feeding, yellow arrows pointing to analogous features on a tidal flat outside of Anchorage, Alaska, and elongate scrape marks made by a crocodilian’s toes as it swam.

primates chittering from the treetops on the shoreline that will one day stumble across their ancient footprints and walking paths and bring these giants back to life, if only as a daydream on this high plains landscape. If you learn to decipher the various trace fossils preserved in sedimentary rocks throughout the world, you too will be able to visit lost worlds that are at once alien and also eerily familiar.

REFERENCES

Buatois, L.A., M á ngano, M.G., 2011, Ichnology. Organism–Substrate Interactions in Space and Time. Cambridge University Press, Cambridge, 358 pp.

Clementz, M.T., Holroyd, P.A., and Koch, P.L., 2008, Identifying aquatic habits of herbivorous mammals through stable isotope analysis: Palaios, v. 23, p. 574–585.

Curran, H.A. (Ed.), 1985, Biogenic Structures: Their Use in Interpreting Depositional Environments. SEPM Spec. Publ., v. 35, 364 pp.

Ekdale, A.A., Bromley, R.G., Pemberton, S.G., 1984, Ichnology. The Use of Trace Fossils in Sedimentology and Stratigraphy. SEPM Short Course 15, 317 pp.

Falk, A.R., Hasiotis, S.T., and Martin, L.D., 2010, Feeding traces associated with bird tracks from the Lower Cretaceous Haman Formation, Republic of Korea: Palaios, v. 25, p. 730-741.

Gingerich, P.D., 1996, New species of Titanoides (Mammalia, Pantodonta) from the middle Clarkforkian (Late Paleocene) of Northwestern Wyoming, Contributions, Museum of Paleontology, The University of Michigan, v. 29, p. 403-412.

Hajek, E.A., Heller, P.L., and Schur, E.L., 2012, Field test of autogenic control on alluvial stratigraphy (Ferris Formation, Upper Cretaceous-Paleogene, Wyoming): Geological Society of America, Bulletin, v. 124, p. 1898-1912.

Halliday, T. J. D., Upchurch, P., & Goswami, A., 2017, Resolving the relationships of Paleocene placental mammals: Biological Reviews, v. 92, p. 521-550.

Liebenberg, L., 1990, The Art of Tracking: The Origin of Science. David Phillip, South Africa, 187 pp.

Lillegraven, J.A., and Ostresh L.M., Jr., 1990, Late Cretaceous (earliest Campanian/Maastrichtian) evolution of western shorelines of the North American Western Interior Seaway in relation to known mammalian faunas, in Bown, T.M., and Rose, K.D., eds., Dawn of the Age of Mammals in the Northern Part of the Rocky Mountain Interior, North America: Geological Society of America, Special Paper 243, p. 1-30.

Lockley, M., Kim, K.S., Lim, J.D., and Romilio, A., 2020, Bird tracks from the Green River Formation (Eocene) of Utah: ichnotaxonomy, diversity, community structure and convergence: Historical Biology, v. 33, p. 1-18.

L ü thje et al., Milàn, J., and Hurum, J.H., 2010, Paleocene tracks of the mammal Pantodont genus Titanoides in coal-bearing strata, Svalbard, Arctic Norway, Journal of Vertebrate Paleontology, v. 30, p. 521-527.

Wroblewski, A.F.-J., and Gulas-Wroblewski, B.E., 2021, Earliest evidence of marine habitat use by mammals: Nature Scientific Reports, v. 11, 8846.

Wroblewski A.F.-J., and Steel, R.J., 2022, Paleocene (65–63 and 58.5 ma) marine flooding and 62–60 ma sediment bypass in southern Wyoming, U.S.A.: Implications for Laramide sediment flux to the Gulf of Mexico: Journal of Sedimentary Research, v. 92, p. 859-894.

Zurano, J.P., Magalhães, F.M., Asato, A.E., Sila, G., Bidau, C.J., Mesquita, D.O., and Costa, G.C., 2019, Certiodactyla: Updating a time calibrated molecular phylogeny: Molecular Phylogenetics and Evolution, v. 133, p. 256-262.

RMAG ON THE ROCKS

CEMEX Niobrara Quarry

Lyons, Colorado

and photos by Ronald L. Parker, Senior Geologist, Borehole Image Specialists, P.O. Box 221724, Denver CO 80222 • ron@bhigeo.com

On a chilly day in late April, an intrepid group of RMAG members carpooled to Lyons, Colorado to venture on a rare, and soon-to-be impossible, field trip to the Dowe Flats Niobrara Quarry operated by CEMEX. The quarry is located on the N side of Highway 66, just to the E of Lyons, CO. Excavation at the quarry has ceased following denial of a 15-year permit extension by the Boulder County Commissioners on 9/29/2022. Currently, the quarry is under active reclamation, which is slated to be

completed in 2 years. During reclamation, 2 million tons of the overburden stockpiled during quarry operation will be placed back into the open pits. The quarry is among the best exposures of the Niobrara along the Front Range, exposing the Codell up to the A Chalk. Because this exposure will be removed from view, the RMAG On-the-Rocks Field Trip was particularly compelling.

This OTR Field Trip was the in-person conclusion

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Text

1: Alan Lindsey records the group excavating some very well-preserved bowl-shaped Inoceramids along bedding planes in the blocky Fort Hays at the NW corner of the quarry. View to the N. Alan is standing on the inclined top of the Codell. Note the inclined strata in the background.

2: The group is here taking in the East-dipping thrust fault in the middle of the outcrop. The feature appears on the N wall of the quarry.

3: Large, bowl-shaped Inoceramids on a bedding plane of the Fort Hays.

RMAG ON THE ROCKS

» CONTINUED FROM PAGE 28

to the Virtual field trip held by RMAG on April 7th , 2022. On the virtual field trip, Brown Hawkins toured attendees around the quarry from the vantage point of a drone. Drone footage provided a unique perspective by providing time-slices of changes in the 3-dimensional geometry of quarry walls and one of the thrust faults revealed by progressive excavation.

In-person field trip attendees had previously read and certified Health and Safety documentation and everyone arrived with required personal protective equipment (PPE – hardhat, steel-toed boots and, eye protection). Reflective, high-visibility vests were distributed to all. Then, Erik Estrada (plant manager) spoke at length about the particulars of the cement manufacturing workflow. Almost all cement manufactured today is Portland cement. The AGI Glossary of Geology defines Portland Cement as “A cement made by grinding a mixture of limestone and shale (or equivalent raw materials), heating the mixture to incipient fusion in a rotary kiln and fine-grinding the resulting clinker.” (p. 509). Some of my notes from Mr. Estrada are summarized here.

The Lyons CEMEX plant:

• Is one of the smallest cement manufacturing facilities in the country. It has one of the smallest cement kilns in the US.

• Has the lowest CO2 emissions of any CEMEX facility

• Has established itself as an environmentally-friendly concrete manufacturer.

• Has a kiln that is 10’ by 250’ which uses 5 million BTUs/hr.

• Is permitted to manufacture 600,000 tons of concrete per year.

• Supplies ~25% of Colorado’s cement consumption needs.

• Does not currently capture CO2, because the plant is too small.

• Is the leading cement plant in the US for reforestation.

• Employs 120 people.

• Welcomes visitors.

After our introduction to plant operational history, we carpooled into the quarry where we stopped to look at an excellent exposure of the B-Chalk/BMarl. The upper part of the exposure was stained

red because of the increased content of pyrite in the overlying A Chalk. Curiously, on the fresh surface, the chalk intervals were not easily differentiated from the marl intervals. Apparently, segregation is more easily made when the rocks have weathered. Detailed examination wasn’t possible, as this 1st outcrop was on the other side of standing water. We next drove to a location at the N end of the quarry that allowed us to get a close view of the rocks. The structural characteristics exposed in the quarry are complex. In different locations, the field trip group observed compressional, extensional and strike-slip structures. The quarry is located on the E-dipping (22°) western limb of the Dowe Pass Syncline - immediately to the W of the Rabbit Mountain anticline. These large-scale fold structures both have generally ~N-S axial trends.

In the Denver-Julesburg Basin, structural adjustment is dominated by normal faulting, with grabens galore. Stylolites in the basin are horizontal, reflecting that sigma 1 is vertical. In the quarry, however, we noted that many stylolites were vertical - reflecting compression by a horizontal sigma 1. One popular characteristic of the Niobrara here is a wide array of fracture fabrics. Many of the fractures displayed open apertures; many were mineralized, many were decorated with slicks and many showed multiple senses of shear. One wide fracture that I brought home was clotted with large calcite crystals that revealed bright white fluorescence at the planar matrix contact transitioning to mild orange fluorescence in the fracture interior.

Fossils were noteworthy and included ichnofauna from the Codell, large, bowl-shaped inoceramids from the Fort Hays and peculiar aquamarine colored “fish scales”.

All-in-all, this was a great day!

WEBLINKS

• https://www.cemexusa.com/products-and-services/cement/ product-specifications

• https://www.cemexusa.com/sustainability

• https://www.cemex.com/

• https://bouldercounty.gov/property-and-land/ land-use/cemex-dowe-flats/

4: Group photo

trip participants

by the drone being flown by Brown Hawkins (behind, and to the left of, the blue hard hat at upper left). Photo

5: Peculiar light blue “fish scale?”

6: The complex structure in evidence at the quarry is hinted in each of the exposed crosssections on display here. In the foreground, the thicker limestone beds of the Fort Hays show a subtle anticlinal warp to the right of the person in red. In the middle distance, the antiformal trace displays greater amplitude. In the distance, the exposed wall displays a thrust fault and a subtle rollover anticline. View to the ESE.

of field

taken

by Brown Hawkins.

RMAG ON THE ROCKS

» CONTINUED FROM PAGE 30

GERMANE REFERENCES

American Geosciences Institute, 2011, Glossary of Geology, 5 th Edition, Revised. Ed. by Klaus K. E. Neuendorf, James P. Mehl Jr. and Julia A. Jackson, Alexandria, Virginia: American Geosciences Institute, 783 pp

Drake, William R. and Sarah J. Hawkins, 2021, Sequence Stratigraphy of the Niobrara Formation: Implications for Age-Constraining Tectonic Events and Stratigraphic complexities in the Denver-Julesburg Basin, United States. AAPG Bulletin, 105(7): 1293-1328.

Longman, Mark W., 2020, Revisiting the Upper Cretaceous Niobrara Petroleum System in the Rocky Mountain Region, The Mountain Geologist, 57(2): 45-66.

Longman, Mark W., Barbara A. Luneau and Susan M. Landon, 1998, Nature and Distribution of Niobrara Lithologies in the Cretaceous Western Interior Seaway of the Rocky Mountain Region, The Mountain Geologist, 35(4): 137-170.

The 2 field trip leaders, Brown Hawkins and Steve Sonnenberg. Dr. Sonnenberg is here explaining some of the remarkable features on display in the CEMEX quarry. When describing some of the controversial ideas regarding Niobrara geology, Steve invoked the “Mandalorian, asking us to rejoinder “This is the Way!”

Are a young geologic professional, student, or transitioning professional seeking career advice & support?

Are you a seasoned geologic professional (510+ years) interested in helping early career & students expand their networks & grow their career?

APPLY TO BE AN RMAG MENTEE/MENTOR!

HYBRID LUNCH TALK

Speaker: Walter Nelson

Date: July 12, 2023 | 12:00 pm - 1:00 pm

Pore Styles and Horizontal Drilling Targets in Niobrara-Equivalent Mancos Shale, Northern San Juan Basin

Presenter: Walter Nelson, Integrated Energy Resources

Horizontal dry gas wells installed in the Niobrara-equivalent section of Mancos Shale in the northern San Juan Basin are now coming on at 25 million cubic feet per day. It has been 12 years since the first horizontal well in this play, yet the potential here is still being revealed. The potential for Haynesville-style consistency and volumes is very real, and those who are excited about it believe in both the Mancos and the significance of future natural gas demand. The 2 primary target units possess many characteristics of other successful unconventional reservoirs and are seen

as relatively calcareous zones (marls) amidst the shale. They are equivalent to the C and B chalks of the Niobrara Formation in the DJ Basin and can be referred to as the lower calcareous unit and the upper calcareous unit, respectively (also sometimes called the olive unit and the black unit by those familiar with WPX’s early investigations with TerraTek). These Cretaceous unconventional reservoirs are classic in every way, exhibiting porosity in fractures, calcareous pellets, and within the organic matter itself.

WALTER NELSON received a B.S. in Geology from Sewanee, an M.S. in Geology from the Colorado School of Mines, and studied business analytics at the University of Denver. He is originally from Houston, TX, and lived in Nashville, TN before moving to Denver, CO where he works as a business development geologist at Integrated Energy Resources. He is primarily focused on reservoir characterization and operations projects for private clients along with various development projects. Previous employers include Triad Environmental Consultants, Antero Resources, QEP Resources, Earth Science Agency, and Kimmeridge Energy. His recent research and work involve Cretaceous unconventional reservoirs, Paleozoic conventional/unconventional reservoirs, Williston Basin development, and natural gas technology.

RMAG Foundation Announces Winners of the Neal J. Harr Memorial Award and the Brown Field Camp Scholarship

The Trustees of the RMAG Foundation are pleased to announce the winners of the 2023 Neal J. Harr Memorial Award and the C. Elmo and Kathleen W. Brown Field Camp Scholarship. The Harr Award is given to outstanding geology seniors at ten colleges and universities in Colorado. The winners are awarded engraved rock hammers and complimentary oneyear membership in RMAG. The Brown Field Camp Scholarship is awarded to defray costs of summer field camp for one student from each of the following Colorado schools: Fort Lewis College and Adams State, Colorado Mesa and Western Colorado universities. The winners of both awards are nominated by the geoscience faculty at their school.

2023 WINNERS OF THE NEAL J. HARR MEMORIAL AWARD

• Simon Bantugan, University of Colorado, Boulder

• Nick Coscarella, Metro State University

• Julia Crowley, Colorado School of Mines

• Cody Fehringer, Adams State University

• Keaton MacMillan, University of Northern Colorado

• Ruth Mosch, Western Colorado University

• Cade Quigley, Colorado College

• Shea Slonkosky, Colorado State University

• Scott Thomas, Fort Lewis College

• M.J. Winey, Colorado Mesa University

2023 WINNERS OF THE C. ELMO AND KATHLEEN W. BROWN FIELD CAMP SCHOLARSHIPS

• Christina Cisneros, Adams State University

• Rachel Mosch, Fort Lewis College

• Andrew Schmidt, Colorado Mesa University

• Western Colorado is not running field camp this season

Please join the Foundation Trustees in congratulating this year’s winners!

WANTED: Colorado Rocks!

RMAG’s Educational Outreach committee wants to create a collection of Colorado rocks that can be paired with the Colorado geological map. The committee will use these rocks as an educational tool to teach elementary, middle, and high school students about the geology of Colorado, geological processes, and Colorado mineral resources.

While you are on your summer vacations to the many wonderful areas in Colorado, please consider picking up rocks for our collection. We ask you note where you collected the rocks and the formation name. ROCKD is a great app that uses your location and geological maps to “map” the formation under your feet. Keep in mind to collect rocks where it is allowed.

Some examples of rocks from formations that we would love in our collection:

• Maroon

• Leadville

• Chinle

• Green River

• Navajo/Nugget

• Entrada

• Lodore

• Dakota

• Sawatch

• Igneous and Metamorphic rocks

• Wasatch

• Volcanics (San Juan – Flat Tops)

When your rocks are ready, contact us at edoutreach@rmag.org

Thank you!

Timothy Lane is an Owner-Geoscientist at Rainbow Consulting LLC in Evergreen, CO

Bradford Burton is the Rady Chair in Petroleum Geology at Western Colorado University in Gunnison, CO

Richard Urash is a Staff Geologist at Continental Resources in Oklahoma City, OK

Kathryn Schuller is a Geoscientist at MI3 Petroleum Engineering in Denver, CO

Keith Jagiello is a Petrophysicist at Petro Data Integration, LLC in Littleton, CO

Mary Gillam is a Geomorphologist for the Colorado Geological Survey in Durango, CO

John Allard is an Exploration Geologist at Brimstone Energy in Silverton, CO

Nora Dwyer is a Geologist at Tetra Tech in Silverton, CO

Josh Reamer is a Geoscience Manager of Development at Ovintiv in The Woodlands, TX

Kari Kirkham works at ConocoPhillips in Houston, TX

Austin Razo-Thompson lives in Broomfield, CO

Natalie Hook is a Geotechnician at from Wheat Ridge, CO

JUNE 6, 2023

RMAG Women’s Group Coffee. DERL- 730 17th Street, B-1. 10 AM-11 AM.

JUNE 4-7, 2023

RMS-AAPG Annual Meeting. Bismarck, ND.

JUNE 7, 2023

RMAG Luncheon. Speaker: Emilie Gentry. “ The Role of Fractures and Fault Zones on Exploration and Development of Geothermal Reservoirs.” Online or In-person at Maggiano’s, Denver. 12:00 PM-1:00 PM.

JUNE 8, 2023

WOGA Golf Clinic. 5:30-7PM. Glenmoor Country Club. Cherry Hills Village.

JUNE 13-15, 2023

URTEC 2023-Denver. Colorado Convention Center.

JUNE 22, 2023

DPC. Speaker Series: Johanna Ostrum. “Oilfield geothermal - Turning Waste Streams into Profit Streams.”

JUNE 27, 2023

RMS-SEPM Luncheon. Speakers: Steve Keller/Mark Longman. “Investigations of the Late Eocene Castle Rock Conglomerate, 1869 to the Present, Including Recent Research on its Diagenesis.” 11:30 AM-1:30 PM. Wynkoop Brewing Company.

OUTCROP

ADVERTISING RATES

FCGS FLOAT TRIP ON THE CHAMA RIVER (31 MILES)

Dates: Friday, July 21 - Sunday, July 23.

Leaders: Dr. Paul Bauer and Dr. Matt Zimmerer, NMBGMR. - THEY WROTE THE GUIDEBOOK!!

Organizer: David Schiowitz.

Transportation: Fort Lewis College vans from the campus and back.

Cost: $750 FCGS members / $780 non-members.

Includes: Transportation to and from Fort Lewis College in Durango, CO., all meals, guidebook, river guides & rafting equipment and most camping gear.

Limit: 13 participants.

Registration: Open now ONLINE ONLY. https://fourcornersgeologicalsociety.org /event/float-trip-the-chama-river-new-mexico/

Cancellation: Full refund if cancel by June 20th.

Drop Dead Date: Trip will be cancelled if minimum registration not reached by July 1st.

Trip Description: The Chama River, in northwestern New Mexico, is a tributary of the Rio Grande, flowing south from headwaters in the San Juan Mountains of Colorado to Abiquiu, then east around the Jemez volcanics into the Rio Grande rift zone. This trip runs from below the El Vado dam through a designated Wild and Scenic River section to the Big Eddy take-out above Abiquiu Reservoir. The exposed geologic section on this stretch is entirely Mesozoic, cutting down from the Cretaceous, Dakota Sandstone to the Triassic, upper Chinle Formation as we travel south. This trip will be led by Paul Bauer and Matt Zimmerer from the New Mexico Bureau of Geology and Mineral Resources (NMBGMR), who published a new geologic river guidebook for the Chama in 2021.

Photos by Paul Bauer