Cherokee Castle: A jewel in the Colorado Rocky Mountains

Mike Viney (USA)

Introduction

The Front Range of the Colorado Rockies is not a place one would expect to find a residence designed in the style of a European castle. So, for me, it was a delightful surprise to learn about the existence of Cherokee Castle in Sedalia, Colorado (Fig. 1).

Cherokee Castle Provenance

The provenance of Cherokee Castle includes two private ownerships and a land trust. Charles (Carl) Alfred Johnson (1868–1954), a real estate tycoon, and his wife Alice Conyngham Gifford Johnson (1893–1950) hired the architect Burnham F. Hoyt (1887– 1960) of Denver to design and build a hunting lodge (Fig, 2). The resulting design includes architectural elements inspired by mid-fifteenth century Scottish castles, including towers with gargoyles. Construction was started in 1924 and, on completion two years later, the residence was christened Charlford after Alice’s son Gifford (1918–2013) and Carl and Alice’s son Charles (1922–2005) (Viney, 2018).

In 1954, Mildred Montague Genevieve Kimball (1914–1999), known as “Tweet” purchased Charlford and an adjoining homestead, renaming her new home the ‘Cherokee Ranch and Castle’. In 1994, Cherokee Ranch and Castle were listed on the National Register of Historic Places. Since 1996, the property has been protected from development by a conservation easement. The Cherokee Ranch & Castle Foundation (CRCF), established by Kimbell, holds the deed to the property acting as a steward, preserving its cultural heritage and natural habitats, and serving the community through public programming (Colorado Preservation, Inc.; Cherokee Ranch Castle).

While Cherokee Castle is the focal point of the ranch, other buildings on the property, dating back to 1873 and 1880, are important historical structures built by homesteaders. In addition to structures built over the last 151 years, there is a rock shelter that has produced evidence of early human habitation on the property 1,000 years ago (Farmer et al, 2024).

Archive of Western civilization and paleoenvironments

The interior of the castle is an archive and repository for Tweet Kimball’s eclectic collection of artifacts representing some of the art and thought generated by Western

civilization. A nineteenth century hand-carved desk, designed in the style of an Italian Renaissance fall-front cabinet, acts as a pedestal for an original Greek vase made during the lifetime of the great philosopher and scientist Aristotle (384–322 BC).

The castle library houses many rare books, including works by William Shakespeare (1564– 1616), and Gaius Plinius Secundus (23–79 AD), better known as Pliny the Elder, a Roman naturalist. A painting attributed to Sir Peter Paul Rubens (1577–1640), one of the most notable Flemish Baroque painters, graces the entry hallway. These are but a few of the treasures visitors can enjoy.

The average person may not realise that the very structure of the castle is also an archive of sorts – one that speaks to some of Colorado’s paleoenvironments. Cherokee Castle is nestled in the foothills of the Rocky Mountains, 30km south of Denver (Fig. 3). This location places the castle in a depressed area geologists refer to as the Denver Basin.

The Denver Basin originally developed during an orogeny, a mountain building event that formed the Ancestral Rocky Mountains during the Paleozoic Era 300 million years ago. As the Earth’s continental plates merged to form the supercontinent Pangea, compressional forces lifted the ancient Rockies skyward (Sweet et al, 2021). The dinosaur-rich, Jurassic-aged Morrison Formation was formed as rivers eroded the mountains away. During the Cretaceous period, the region subsided and the Western Interior Seaway formed, depositing thousands of meters of sediments.

The Denver Basin deepened as another mountain building event known as the Laramide orogeny started to form our modern Rocky Mountains, 80 million years ago during the late Cretaceous. Uplift of the Front Range led to the development of river systems that deposited debris into the subsiding Denver Basin. Cretaceous and Paleogene sediments filled the Denver Basin, many of which are rich in fossils. Plant and dinosaur fossils, such as the first Triceratops discovered by Othniel Charles Marsh (1831–1899), an American palaeontologist, in the Spring of 1887 near what is now Empire Field at Mile High in Denver, Colorado help to document life along the Front Range during the late Cretaceous.

The K-Pg boundary that marks the end Cretaceous mass extinction event is well represented in the strata of the Denver Basin sediments. Plant leaf fossils found in early Paleocene strata near Castle Rock exhibit great diversity and indicate a more rapid recovery in this area after the K-Pg impact event than previously thought (Raynolds et al, 2007). Strata in the Denver Basin record fluvial (river) and volcanic activity as well. Much of the material used to construct Cherokee Castle was mined from strata that accumulated in the basin during the Paleogene Period. The rocks used as architectural material can be ‘read’ by geologists and have fascinating stories to tell.

A violent, Eocene-aged volcanic eruption

The Castle’s walls and arches are made primarily of a rhyolitic tuff from the Castle Rock area – this dimensional stone is made from the Wall Mountain Tuff (Fig. 4). During a tour of the castle’s exterior, I marvelled at the care stonemasons took in shaping the dimensions of each stone. However, to fully appreciate each stone, there is a fourth dimension one must contemplate – time. These beautiful rhyolite stones were not always blocks and, in some distant future, will not remain as blocks. The Wall Mountain tuff from which these stones were made records a cataclysmic late Eocene-aged volcanic eruption.

Thirty-seven million years ago, an explosive volcanic eruption in the present-day area of Salida and Buena Vista, Colorado resulted in a pyroclastic flow, an incandescent cloud of gas and debris with temperatures of 1,000°C and travelling at 160km/h or more (Epis and Chapman, 1974; McIntosh and Chapman, 1994). The gasses in such an ash flow suspend the hot debris, which allows the volcanic material to travel great distances (Matthews, KellerLynn, and Fox, 2003).

As the hot mixture of ash, minerals, and volcanic glass making up the pyroclastic flow glided across the landscape, ecosystems along its path were undoubtedly destroyed in an instant. The pyroclastic flow followed the contours of the landscape and as it came to rest the hot material fused into an ignimbrite or welded rhyolitic tuff. This extrusive igneous rock is similar in composition to intrusively formed granite, but cooled more quickly resulting in smaller crystal sizes.

Remnants of the Wall Mountain Tuff in Castle Rock, just south of Denver, indicate that this ancient pyroclastic flow travelled a distance of at least 150 km from the eruption site (Meyer, 2003). The Molly Brown house in Denver is also made from the same rhyolitic tuff (Matthews, KellerLynn, and Fox).

Rivers erode the Rocky Mountains

The walls of the castle also incorporate sandstone and pebble conglomerate rocks formed from rivers eroding the Rockies during the late Paleocene and early Eocene.

Conglomerate is a coarse-grained clastic sedimentary rock made from the consolidation and lithification of gravel (Fig. 5 Left). Conglomerates can be made from pebbles, cobbles, and even boulder-sized clasts. Clast size can be a clue to the energy of the river that deposited the gravel. For example, the foundation upon which the castle is built is a sand, pebble, and cobble conglomerate that formed from a river system with more energy than the one that deposited the sand and pebble conglomerate used for the base of the walls (Fig. 5 Right).

The direction and flow of these paleochannels can be understood by mapping the conglomerate deposits and by determining the origin of igneous rock formations that served as a source for the pebbles and cobblestones (Keller and Morgan, 2013; Koch, Coleman, and Sutter, 2018).

While the sandstone and conglomerate rock inside the castle walls was carefully sized for the purposes of construction, a prehistoric shelter on the property made by the natural weathering and erosion of Castle Rock Conglomerate holds clues to early human habitation along the Front Range. Pieces of ceramic sherds, mammalian bones, and projectile points record activity in the area between AD 1000–1600. Obsidian found at the shelter can be traced to two sources, one in eastern Idaho and the other in north-western Wyoming – clues that suggest there may have been regional trading network in prehistoric times (Farmer et al, 2024).

Ancient tropical forests

There is a third type of rock incorporated into the walls and arches of the castle that may surprise many visitors. Thousands of petrified wood specimens gathered locally from a fossil wood deposit elsewhere on the CRCF property were used to supplement the stones of rhyolitic tuff and sandstone pebble conglomerate used to build the castle walls. Even a casual examination will reveal these pieces to be former wood that has turned to the nature of stone, commonly known as petrified wood (Fig. 5 Left).

The most impressive specimens in the fossil forest have the appearance of large tree trunks. They are in fact, partial trunks lying prostrate in arkose sandstone, absent their bark and limbs. This geologic setting reveals the trees were transported and deposited within a fluvial (river) environment roughly 55 million years ago during the Palaeocene.

The fossil wood is mineralised with silica that was most likely provided by volcanic activity. Cells making up the wood acted as a template for silica deposition preserving subcellular details of cell walls in opal CT, chalcedony and quartz (Mustoe and Viney, 2017). The preserved structure can be used to identify the ancient tree types.

The fossil wood deposit on CRCF property represents angiosperms (flowering plants) exclusively – most have strong affinities to the present-day Laurel family. Pieces of wood in the castle walls that display a transverse view reveal diffuse porous woods that have indistinct growth rings, evidence of little seasonality (Fig. 6). The cell structure of the fossil wood is consistent with other Paleocene and early Eocene woods described from the Denver Basin (Wheeler and Michalski, 2003).

Evidence from Palaeocene-aged fossil leaves and wood indicate a paleoclimate that was tropical for the Front Range (Wheeler and Michalski; Raynolds et al, 2007). Evidence for tropical conditions of the past might come as a surprise to Coloradoans who live in a semi-arid environment, where cold winters and draughts are common occurrences. Furthermore, it is the strata formed during the Paleogene Period which trapped ancient waters that today are mined for use by many people along the Front Range corridor.

Early Palaeozoic oceans

At least one rock type used to construct Cherokee Castle was not collected in Colorado; rather, it was quarried in Vermont (Colorado Preservation, Inc.). In this respect, the castle sports a slate roof – a foliated metamorphic rock, (Figs. 1 and 7).

The slate making up the roof represents the oldest rock used to construct the residence and started to form at a time when life on Earth was restricted to the oceans (Fig. 8).

Clay and sand deposited in Cambrian and Ordovician oceans located in what is now the northeast coast of the United States formed shale (Dale, 1914). Regional metamorphism during a mountain building event created environments deep in the Earth’s crust with high pressures and low temperatures that recrystallized the shale into slate. Slate has been mined in Vermont since the mid-nineteenth century and is in fact one of Vermont’s state rocks.

Conclusion

The structural depression geologists refer to as the Denver Basin served as a repository for sediments and volcanic debris, catching and recording evidence of paleoenvironments shed from the Front Range uplift during the Laramide orogeny (Barkmann et al, 2015). The material to make much of Cherokee Castle was mined from strata formed in this basin.

“If these walls could talk, what stories they would tell” is a well-known English phrase. Close examination of the stones making up the walls, arches and roof of Cherokee Castle reveal they do have stories to tell – stories of ancient oceans, tropical forests, rivers, floods, and volcanic eruptions. I encourage the reader to take part in one of the many special events offered by the Cherokee Ranch & Castle Foundation to learn more about this jewel of the Colorado Rocky Mountains.

About the author

Mike Viney completed a 30-year career teaching secondary science for Poudre School District in Fort Collins, Colorado in 2017. He currently works as a science educator at the College of Natural Sciences Education and Outreach Center at Colorado State University. Viney is a co-founder of the Friends of Fossil Forests.

Acknowledgements

I would like to thank Herb Meyer, Florissant Fossil Beds Palaeontologist and Don Viney, Professor of Philosophy at Pittsburg State University for their helpful comments, Shaun Boyd Archivist for Douglas County History Research Center for permission to use image 2007.032.0019, George Mustoe, Geology Department Research Associate at Western Washington University for his comments, map, and geologic diagram, Dustin Sweet, Associate Professor at Texas Tech University, for sharing his expertise on the tectonic mechanisms associated with the uplift of the ancestral Rocky Mountains, and Donna Smith, Community Partner & Client Services Consultant Cherokee Ranch & Castle, and T. Reid Farmer, head Archaeologist at Cherokee Ranch, and the late Al Koch whose Cherokee Ranch Science Institute’s research findings are now shared by Cherokee Ranch & Castle Foundation. Without this non-profit cultural organization, the public would not likely have access to the research or this historic site.

References

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