Hartville Uplift

When considering the Hartville Uplift, one may not realize just how much the area’s geologic resources have contributed to our cultural history. Nearly 13,000 years ago, in eastern Wyoming at the location of the historic Sunrise Mine, Paleo-Indians mined red ochre or hematite at what is now considered by archaeologists as one of the oldest mining sites in all of North America!

Mine Workers
Workers of the Chicago Mine in 1912, Sunrise, Wyo. [Credit: American Heritage Center, by A.C. Boyle]

Chipping stones were also discovered at “Spanish Diggings” also within the Hartville Uplift. These ancient quarries were first thought to be the result of gold-prospecting expeditions from the Spanish. However, by 1935 archaeologists were documenting the 10,000+year history of Indian groups on the High Plains. It then became more accepted that this was likely the work of groups of hunters that had lived in the region and quarried stone for projective points, knives, scrapers and other tools.

The Hartville Uplift is a structural arch that connects the Laramie Range with the southern Black Hills. It is about 25 miles (north to south) by about 45 miles (east to west). The Laramie Range is to the west and the North Platte River flows along the uplift’s western and southern boundaries.

Fast-forward to the 1800s, through the trajectory of cultural change, the rocks of the Hartville Uplift were discovered to contain copper and iron resources. In the early 1900s, up sprung the mining town of Sunrise and just outside of the company-owned town, the rough and tumble town of Hartville, the oldest incorporated town in Wyoming.

Red Ochre and Clovis

By Chamois Andersen

Between 11,500 and 13,000 years, it is considered one of the oldest mining sites in North America. Discovered at the historic Sunrise Iron Mine, near Hartville, red ochre mined by Paleo-Indians was used as a pigment. Similar red ochre has also been recorded at prehistoric burial sites around the world.

George Frison
Dr. George Frison, Paleoarchaeologist of the Century, Society for American Archaeology. [Credit: Chamois L. Andersen, WSGS]

Archaeologists excavating the ancient mine at the Sunrise location have also discovered Clovis points made of blue, agate-type material along with other Paleo-Indian artifacts. The area is rich in all sorts of hard rocks known as cherts, including pink, dark brown, red and gray, along with the limestones and dolomites of the Guernsey and Hartville formations.

Red Ochre and Clovis - Wyoming's Cultural Geology Guide

Archaeologists and geologists have collaborated to better investigate the source of the chipping material. At the Sunrise Mine they noted a rich deposit of chert, jasper, and quartzite, materials commonly used to create tools and projectile points. The agate material may have resulted from a mass movement of rock, or by water movement along faults in the area

Prolific archaeologist, Dr. George Frison is a world-renowned expert on Clovis points and Paleo-Indian archaeology.

The Clovis Culture

Clovis points
Dr. George Frison, displays Clovis points discovered at the Sunrise Mine. [Credit: Chamois L. Andersen, WSGS]

The earliest Paleo-Indian settlement is associated with the Clovis point, which is found over much of North and Central America. The Clovis tradition, named after a town in New Mexico, once flourished in various forms over much of the Americas. Clovis bands traveled across the plains at the end of the Ice Age, hunting big game, including bison, mammoth and other animals. In some areas, wild plant foods were probably as important to their diet. Fish and ocean mammals may have also been of importance along the coastal areas where they traveled. They were experts in tool making and used stone-flaking technology to produce hard, fluted-based points. The hunters mounted these on long wooden shafts. The photo on the left includes Clovis points discovered at the Sunrise Mine, Platte County, Wyo.

Hartville, Wyo

By Julie Francis

Mining and mineral development form a bridge between the ancient and modern peoples of the Hartville Uplift. Just as Native Americans mined red ocher from the iron deposits and dug thousands of tons of quartzite and chert for tool-making and trade, copper and iron ores provided the major impetus for development of the region by European and American settlers during the 19th century.

Hartville, Wyoming
Hartville, Wyoming in 1900. [Credit: American Heritage Center]
The Sunrise Mine

The short-lived copper boom between 1880 and 1887 gave start to the founding of Hartville in 1881. With a good water supply at Indian Springs in what is now the town park and 75 miners working at the Glory Hole about one mile east, Hartville quickly became the primary rough-and-tumble mining camp of the area. Just as quickly, the boom went bust as the price of copper dropped, freighting costs (by mule train) were high, and the copper veins played out. By 1887, copper mining had mostly ceased. However, miners began prospecting for other ores and discovered iron ore beneath the copper layer at the Glory Hole. By the late 1890s, vast iron-bearing rocks about eight miles long and three miles wide had been documented, with the most productive areas centered around Hartville and the old copper Glory Hole, now known as the Sunrise Mine. By 1898, the Colorado Fuel and Iron Co. had leased nearly all the claims in the area and eventually purchased the property in 1904. They invested in building a railroad from the mine through Hartville and south to Guernsey for shipping the ore to the smelter outside of Pueblo, Colorado and built the company town of Sunrise next to the mine.

This proved to be a boon to Hartville, as private business was banned in Sunrise. By 1900, Hartville had nine saloons and two dance halls near completion, with a lodging house under construction. The town was run by the saloon-owners and offered alternative goods and services to the company store in the well-ordered community of Sunrise. The saloon keepers incorporated Hartville in 1901, and it remains the oldest incorporated community in Wyoming. There were some trappings of civilization, including a school that opened in 1901, a graded main street in 1907, streetlights, public garbage collection and a privately owned telephone service in 1910 to 1912, and a new jail in 1913. However, gambling and prostitution remained the primary sources of income for the community until about 1915. Hartville’s peak population reached 776 in 1900 and included Italian, Greek, Scandinavian, English, Middle Eastern and Japanese emigrants. Soon after, the population began to drop as the Sunrise community grew. The Sunrise Mine eventually closed in 1980, and today only 62 residents are listed on the census. The wood frame and masonry buildings and quiet streets offer only a hint of the wild times here during the early 20th century.


Penny, D., 1996, Site form, 48Pl83: On file at the State Historic Preservation Office, Cultural Records Office, Laramie, Wyo.

Rosenberg, R.G., 1995, Copper and iron mining in the Hartville Uplift, Goshen, Platte, and Niobrara Counties, Wyoming, 1879-1980: National Register of Historic Places Multiple Property Nomination Form. in Carender, P.L., J.B. Tyler, and R. G. Rosenberg, 1995, Class III cultural resource inventory of Spectrum Engineering Abandoned Mine Lands Project 10-111, Platte and Goshen Counties, Wyoming. Prepared by Frontier Archaeology, Worland for Spectrum Engineering: On file at the State Historic Preservation Office, Cultural Records Office, Laramie, Wyo.

The Sunrise Iron Mine

By Wayne Sutherland

The Hartville uplift hosts a wide variety of chalcedony in sedimentary rocks and in some veins. The Guernsey Limestone (Devonian-Mississippian) is a source of many agates and jaspers in colors that include red, purple, blue, brown, and yellow, along with moss agate, dendritic agate stalactitic agate, and youngite agate.

The Sunrise Mine

Copper ore was mined in the district from 1880 until 1887, with iron production by Colorado Fuel and Iron Co. (CF&I) beginning at the Sunrise mine in 1898 after a 10-year period of prospecting and exploration.

Sunrise Iron Mine
The Sunrise Iron Mine was purchased by CF&I in 1904. [Credit: American Heritage Center]

Iron mining of the Sunrise property began in 1898–1899 and continued until 1980 when the mine closed. In 1947, the Sunrise and adjacent Chicago properties included a large open pit and underground mine. Total production during 1900–1980, from all ore bodies, including the Chicago Mine, was about 42,454,000 tons. A current estimate for iron in the Sunrise area is around 24.5 million tons or more.

Rocks cropping out in the Sunrise area in the center of the Hartville Uplift include the Precambrian Whalen Group, overlain by the Mississippian-Devonian Guernsey Formation, which is overlain by the Pennsylvanian Hartville Formation. Iron-bearing rocks occur in the Whalen Group, a thick sequence of green schists, quartzites, dolomites, micaceous schists, and graphite schists. Hematite ore (or red ochre mined by Paleo-Indians) occurs in the lower part of the Good Fortune Schist which is faulted and part of a steeply east-plunging synform. Ore bodies appear localized in cross-folded zones superimposed on the synform in the thickest part of the Good Fortune Schist.

Frey (1947) described the country rock surrounding the iron ore as schist and an impure, hematite- and limonite-stained flint and interpreted the iron ore to be a replacement of the schist. Lenticular bodies of red iron ore are enclosed by schist, immediately above the uppermost limestone of the older Precambrian rocks; a thin layer of iron-stained, siliceous schist separates the iron ore from the limestone. Frey (1947) described two varieties of iron ore: fine-grained, red, generally schistose, and soft, referred to as “paint ore” or ochre, and fine-grained, dark bluish-gray, hard, compact ore with a smooth fracture, referred to as “blue ore,” which is the more valuable of the two. The “paint ore” has a deep red hue, is somewhat greasy to the touch, and leaves a rusty, metallic stain on contact. The ochre contains 57 percent Fe2O3, while the “blue ore,” is a dense, bluish-black hematite with a rusty surface that yields about 89 percent Fe203.


Miller, J.C., 2009, Lithic resources, in Kornfeld, M., Frison, G.C., and Larson, M.L., 2009, Prehistoric Hunter-Gatherers of the High Plains and Rockies (Third Edition): Left Coast Press, Walnut Creek, CA, p. 553-598.

Hausel, W.D., and Sutherland, W.M., 2000, Gemstones and other unique minerals and rocks of Wyoming - A field guide for collectors: Wyoming State Geological Survey Bulletin 71, 268 p.

Sutherland, W.M., and Cola, E.C., 2015, Iron Resources of Wyoming: Wyoming State Geological Survey Report of Investigations No. 67, 92 p.

The "Spanish" Diggings

By Julie Francis

Upon their arrival in the late 19th century, settlers in the Hartville area found a landscape pocked with pits, craters, trenches, and tunnels and littered with reject material. The massive nature of the excavations led to the assumption that Spanish conquistadors prospecting for gold were responsible, hence the name “Spanish Diggings”. The area attracted the attention of the Bureau of American Ethnology, the Field Museum of Chicago, and later the National Geographic Society and University of Wyoming. Scientists who visited the area quickly debunked the Spanish myth and realized that the extensive excavations were the result of stone quarrying by Native Americans, in search of high quality toolstone.

Spanish Diggings
Spanish Diggings, Platte and Niobrara counties, Wyo. [Credit: American Heritage Center, 1894]

Spanish Diggings extends from modern day U.S 26 on the south to U.S. 18 on the north, and from I-25 on the west to U.S. 85 on the east. It encompasses much of what geologists recognize as the Hartville Uplift. This is a structural arch in which Pre-Cambrian, Paleozoic, and Mesozoic rocks were uplifted during the Laramide Orogeny. Though much of the uplift has been buried by younger sediments, extensive exposures of several Paleozoic and Mesozoic formations which contain extremely high-quality cherts and orthoquartzites are common. Fine-grained purple, gold, grey, tan and red orthoquartzites occur in the Morrison-Cloverly formations, and several cherts (often a butterscotch color with black dendrites) can be found in the Mississippian age Guernsey and Hartville formations. Native Americans went to extraordinary efforts to mine these exposures for the highest quality material, leaving tons of reject material in their wake. Stone wedges, hafted and unhafted hammerstones, bone and antler served as digging implements. Once blocks were removed, preliminary flaking to shape cores, blanks and performs which were then transported away from the quarries for future use happened. Thousands of domestic structures and camps throughout the Hartville Uplift also illustrate the extensive use of the area.

Artifacts made from Spanish Diggings quartzites and cherts have been found across Wyoming and throughout the Northwestern Plains. Native Americans quarried materials in the Hartville Uplift during Paleo-Indian times (ca 12,000 years ago) and continued mining until the Historic Period. Large ceremonial bifaces made of Mississippian age cherts, possibly from the Spanish Diggings, have been found in Hopewell burial mounds as far away as LaCrosse, Wisconsin. This find points to the important role the Spanish Diggings quarries played in the economic and social aspects of Native American cultures for thousands of years.


By Wayne Sutherland

The quarry at Spanish Diggings was mined prehistorically for orthoquartzite from the Morrison-Cloverly Formations in the Hartville uplift as a source for stone tools. It is commonly tan, brown, purple, maroon, and gray and lacks invertebrate trace fossils.

The Hartville Uplift is an elongated north-northeast trending structural arch approximately 40 miles long, which was uplifted during the Laramide Orogeny. The area is bounded on the east by a high angle fault, with the Hartville Uplift on the western, up-thrown block. The Spanish Diggings are hosted in outcrops of the Upper Jurassic Morrison Formation and Lower Cretaceous Cloverly Formation on the central-western slope of the uplift. The Morrison-Cloverly outcrops cover about 15 square miles and are surrounded by the overlying Miocene Arikaree Formation and on their southeastern edge by the Oligocene White River Formation, which is also overlain by the Arikaree.

Yellow and red chert nodules are found in the Pennsylvanian-Mississippian Hartville Formation and the Mississippian-Devonian Guernsey Formation along the flanks of the central part of the Hartville uplift. Similar to Mississippian rocks in other parts of Wyoming, these chert nodules may contain manganese dendrites. Much of these cherts are reported to be of poor quality for stone tools; however, some areas of good quality are known.

Geology of the Hartville Uplift
Geology of the Hartville Uplift. [Credit: Wyoming State Geological Survey, 2015]


Boszhardt, R.F., 1998, Addition western lithics for hopewell bifaces in the Upper Mississippi River Valley: Plains Anthropologist 43(165), pp. 275-286.

Dorsey, G.A., 1900, An Aboriginal quartzite quarry in eastern Wyoming: Publication No. 51, Anthropological Series II(4), Field Columbian Museum, Chicago.

Holmes, W.H., 1891, Handbook of aboriginal American antiquities: Bureau of American Ethnology Bulletin No. 60, Washington, D.C.

Kornfeld, M., Frison, G. C., and Larson, M.L., 2010, Prehistoric hunter-gatherers of the High Plains and Rockies: Left Coast Press, Walnut Creek, California.

Miller, J.C., 2009, Lithic resources, in Kornfeld, M., Frison, G.C., and Larson, M.L., 2009, Prehistoric Hunter-Gatherers of the High Plains and Rockies (Third Edition): Left Coast Press, Walnut Creek, CA, p. 553-598.

Miller, J.C., 2010, Lithic resources, in Prehistoric hunter-gatherers of the High Plains and Rockies by Kornfeld, M., Frison, G.C., and Larson, M.L.: Left Coast Press, Walnut Creek, California, pp. 553-598.

Saul, J.M., 1969, Study of the Spanish Diggings, aboriginal flint quarries of southeastern Wyoming. National Geographic Society Research Reports, 1964 Projects, pp. 183-199.