Geomorphology

Introduction

The Paint Mines Interpretive Park is the newest park in the El Paso County Colorado park system. The park covers 750 acres and has approximately four miles of trails. The park is small and the hike is appropriate even for beginners, although the overall rise in elevation is over 500 feet. There are a couple of rules to follow while exploring the Paint Mines. One is that there is no rock climbing in this fragile environment. Also, everything is protected by law, including artifacts, rocks, plants, and animals, so leave the beautifully colored rock fragments that litter the paths where they are for others to enjoy!   

Attraction
Of particular interest here are the beautifully colored, weathered sandstone formations that include numerous hoodoos, fins and spires. These formations have been shaped by years of erosion exposing the layers of selenite clay and sandstone.  

Photo 1. Fins. (Photo by Susan P.)

Paint Mines Interpretive Park also has a great historical significance. Researchers have found evidence of human habitation in the area for as far back as 9,000 years ago. These people are believed to be ancestors of the first humans to cross the Bering Strait land bridge. In more recent years, the Native Americans considered the area a cache of natural resources. The selenite clay was used to make arrowheads and the beautiful colors of the sandstone were used as pottery paint. To make hunting easier, the channels were used to run buffalo into so that hunters sitting at the end of the gulches above could shoot them with bow and arrow. 

In the spring, the park is full of flora like the Indian Paintbrush and Buffalo grass along with many other native wildflowers and grasses. Wildlife that can be seen in the area includes horned toads, antelope, coyotes, hawks and many varieties of song birds.

General Landscape

The Paint Mines Interpretive Park is located on the eastern plains of Colorado approximately 35 miles east of the base of Pikes Peak. The area is in a rain shadow produced by the Rocky Mountains creating a grassland climate. Therefore the amount of precipitation received throughout the year is relatively low. Winter precipitation is an average of 0.3" with the wet season occurring in late spring to early summer with an average of 2.4" for two to four months of the year. Average temperatures are 42F/8F in the winter and 85F/54F in summer.

The general physical geography of the region is characterized by rolling hills making the Paint Mines a geographic anomaly. Formations are composed of selenite clay and highly eroded sandstone deposited 65 million years ago. Fluvial and eolian erosion are the driving forces in the formation of some very remarkable configurations.  

Landform

The Paint Mines depict the rarely seen interface of the D1/D2 layers of the Denver Basin. The layers of the Denver Basin from bottom up are: Pierre Shale, Fox Hills Sandstone, Laramie Formation, D1 synorogenic sediments, D2 synorogenic sediments and on top in small areas Castle Rock Conglomerate. Strata of the D1 synorogenics were deposited between 69 and 64 million years ago, while the D2 synorogenic strata were deposited 54 million years ago. The main theory for the discontinuity in the deposition of material is that there was a period of weathering in between the two layers (Raynolds, 2002).

The D2 layer is composed of grus that has weathered from the Pikes Peak Batholith (Raynolds, 2002). This grus is derived from the Laramide orogeny that occurred from the Cretaceous to the Tertiary periods (Raynolds, 2002). This layer is capped with a highly friable layer known as the Wall Mountain ignimbrite that covered the front range approximately 36 million years ago (Raynolds, 2002). 

The D1 layer is a fine grained mudstone that is capped with a shale enriched sediment. Although these layers of the Denver Basin are attributed to orogenic activity they would not have settled in these areas without fluvial action. Both the D1 and the D2 layer were eroded from the Front Range and deposited on the plains by fluvial systems draining from the higher elevations.

As in most places in the world weathering and erosion occur in a combination of forces within the Paint Mines. Mechanical weathering by way of water, wind and plants is the dominant force here. Frost wedging is a key component in this landscape. Temperatures in the winter can easily go from 5F to 65F and back within a 24 hour period. Is the large formation in Figure 4 split from frost wedging or something else?

Although a small contributor in this climate plants such as lichen also contribute to biological weathering with the excretion from their roots.

Due to the semi-arid climate of the region erosion is transport limited. While walking the trails of the Paint Mines you will find many small shards of the stained sandstone, selenite clay and the Wall Mountain ignimbrite that compose this beautiful landscape as seen in Photo 5.

Photo 5. Transport- limited weathering (Photo by Susan P.)

Erosion here occurs by fluvial and eolian forces. Fluvial erosion works at both a small and large scale. When hiking in the Paint Mines be sure to take a very close look at the formations where selenite clay is present. When viewed close up, you can actually see where even small rivulets of water are creating tiny grooves on the selenite formations. 

The larger scale fluvial occurrences are much more noticeable, especially by the fact that half of the trails are actually ephemeral streams that run through the park. Typical rain events in this area come quickly; raining hard and exiting fast. The exertion of this force can be seen in the trough that has been eroded into the caprock in Photo 6. Rain flowing over the caprock and down the formations below also weather and erode the fragile formations. Note the long U-shaped indentation in the formation shown in Photo 7 (yes the photo is upside right!). 

Photo 6. Fluvial erosion in caprock (Photo by Susan P.)

Photo 7. Weathering in wall of sandstone formation (Photo by Susan P.)

Hazards Found at Paint Mines Interpretive Park

There are many hazards at the Paint Mines. One thing to watch is the weather. Thunderstorms can develop very quickly and produce large amounts of lightning, rain and the occasional tornado. There is no shelter and since some of the trails are actually ephemeral washes they can quickly start to flow during heavy rain events. Watch your footing, large rain events have created areas of erosion on the trails. Wildlife is something else to be careful of. There are rattlesnakes and coyotes in the area. Please, no climbing on the formations, the Paint Mines is a fragile environment..

Conclusion
As with any hiking trip, plan ahead and be careful. Remember we are just visitors on this planet and we should preserve what we can. Tread lightly and stay on trails, this is a delicate environment. All plants, animals, rocks and artifacts are protected by law so leave them where they are for others to enjoy.  

Driving Directions and Google Earth .kmz File

Google Earth Placemark File (.kmz) file: link
Driving Directions from Downtown Colorado Springs:

• Take Austin Bluffs Parkway east from Colorado Springs. 

• From the UCCS campus, go 6.4 miles to Woodmen Road and turn right.

• Go 7.5 miles to Highway 24 (Woodmen Road will end here) and turn left. 

• Take Highway 24 for approximately 19 miles to the east side of the town of Calhan and turn right on N. Calhan Highway. 

• Approximately 1/2 mile north on N. Calhan Highway is Paint Mines Road, turn left. 

• Now heading east, travel for about a mile and the road makes a 90 degree turn to the north. 

• Continue on for another 1/2 mile to the parking area for the Paint Mines Interpretive Park on the left.