Planetary Geology on Earth: Red Rock - Red Planet
This is an EarthCache that will take you to a geological feature in Osage Hills State Park, which is east of Pawhuska. There is no entrance fee to the park. However, there is a parking fee (you may apply for a free senior pass for Oklahoma state parks online or at the park office if you have a copy of your vehicle registration renewal). There is no container to find. To log this cache as a “find,” you will need to complete the logging tasks at the bottom of the description.
How to get there
The geological feature is on the “red” trail about 1 mile from the parking lot (coordinates are in a waypoint, and a trail map is available in the park office). There are two trailheads to access the trails (waypoints are included), and both require crossing a stream on stepping stones. The red trail going south is a fairly easy hike once the stream near the trailhead is crossed, with no significant change in elevation. You will not have to leave the trail to find the EarthCache.
Observations at the EarthCache
A small area of spherical nodules are cemented together and resting atop the surrounding rock. On the trail are fragments of the surrounding rock formation that can be examined.
Photo by Nancy von Seggern, 1/1/2024
Spherical shapes (“nodules”) in rocks occur in a variety of geological settings and have a wide range of appearance. Two types are ooids and iron concretions.
Ooids
Ooids are tiny, spherical grains that are formed when layers of calcite or other minerals form around a sand grain or other nucleus. Ooids cemented together in clusters form a type of sedimentary rock called oolite, which is usually limestone.
Iron Concretions
Iron concretions typically are spherical, but may also be odd shapes, such as cylindrical. They may be singular or fused together with a few other concretions. If the surrounding, softer rock erodes away, the concretions are released and may form puddles or roll downhill.
Iron concretions form in reddish and orangish sandstones, which contain iron-rich minerals, giving the sandstone its rust-like color. When groundwater circulates through the sandstone, it dissolves some of the iron. The soluble iron then precipitates out and acts as a cement to bind sandstone into the round iron concretions.
Limestone versus Sandstone
Limestone is a chemical sedimentary rock made mostly of calcium carbonate. Most limestone is formed when biological matter containing calcium carbonate lithifies into stone or when calcium carbonate precipitates out of water as crystals. Limestone has a range of colors, depending on the minerals present with the calcium carbonate, including white, gray, and brown, with shades of blue, green, pink, and red. Limestone is a soft rock, and can be scratched with your fingernail.
Sandstone is a clastic sedimentary rock made of weathered bits of minerals where most of the sediments are sand-sized grains that are visible, and it is usually gritty to the touch. Sandstone commonly is made of quartz, feldspar, mica, and clay, and has a range of colors depending on its mineral content, including gray, yellow, orange, and red. Sandstone may be hard or soft, depending on its mineral content. One distinguishing factor is that sandstone may have a visible stratification of layers that limestone does not have.
Mars Concretions
Mars Gale Crater - 2012
Photo Credit: NASA/JPL-Caltech/MSSS
The image above was taken by NASA’s Mars rover “Curiosity” in Gale Crater’s Yellowknife Bay in 2012. The spherical features are interpreted to be concretions. (The image was white-balanced by NASA to show what the rock would look like on Earth.)
Mars Fram Crater - 2004
Photo credit: NASA/JPL-Caltech/Cornell/USGS
In 2004, NASA’s Mars rover “Opportunity” sent back images of spherical rocks that became known as Martian “blueberries” because the false-color images gave the spheres a bluish color. The image above was taken near Fram Crater on April 19, 2004. The original image is 1.2 inches across.
Mars Concretions Compared with Earth’s Concretions
The Mars concretions share characteristics with Earth’s iron concretions. Studies indicate that the Mars concretions contain hematite, a form of iron-oxide, and that the concretions are better cemented than the more easily weathered host rock (the rock surrounding and under the concretions). The Mars concretions are also comparable in size and organization to typical Earth iron concretions, which are found as single spheres or as doublet or triplet forms, rather than clusters that are touching.
Acknowledgment
Thank you to Molly L. Yunker, Ph.D., Education & Outreach Coordinator, Oklahoma Geological Survey, University of Oklahoma, for identifying this geological feature.
To get credit for this EarthCache
A. Send your answers to the questions below in a message. Do not post your answers in your log.
B. In your log, include a photograph of the spherical nodules at this EarthCache with yourself or a personal object in the photograph. You may log the find before you send your answers.
Logging Tasks
Answer the following questions:
1. What do you observe that indicates whether the spherical nodules you see at this EarthCache could be ooids or iron concretions?
2. What similarities and differences do you see when comparing the spherical nodules in this EarthCache with the Martian concretions shown in the image from Gale Crater taken in 2012?
3. What similarities and differences do you see when comparing the host rock (the rock under the nodules) in this EarthCache with the host rock of the Mars concretions shown in the image from Gale Crater taken in 2012?
Sources
Tarbuck, E., & Lutgens, F. (2006) Earth Science, Prentice Hall.
Chan, M., Bowen, B., & Parry, W., “Red rock and red planet diagenesis: Comparisons of Earth and Mars concretions,” Department of Geology and Geophysics, University of Utah, GSA Today, August 2005 (available at rock.geosociety.org).
Mitton, J., “Pondering puzzling patterns in sandstone,” Colorado Arts & Sciences Magazine, Sept. 12, 2015 (available at colorado.edu).
NASA, mars.nasa.gov
Permission
Permission for this EarthCache was granted by the Oklahoma State Parks Department. A signed use permit is on file.
NASA/JPL photographs may be used for educational and informational purposes without prior permission. https://www.nasa.gov/nasa-brand-center/images-and-media/. https://www.jpl.nasa.gov/jpl-image-use-policy