Welcome
Monument Rocks was chosen by the U.S. Department of the Interior as the first national natural landmark in the 1960’s. On January 29, 2008, Monument Rocks and Castle Rock were jointly named as one of the Original 8 Wonders of Kansas.
The formations are situated on private property, and the landowners generously share this wonder of nature with the public. Please treat the site with respect and remember you are a guest here. The land owner insists no climbing occur on the rocks, and open fires are not allowed. Please do not dig for fossils. The Monument Rocks area is undeveloped, and as such there are no restroom facilities or running water at the site. There is no fee to visit the Monument Rocks area.
The unpaved county roads to Monument Rocks, from which you can observe this EarthCache, should not be traveled in wet or snowy conditions as your vehicle may become stuck. The roads are easily traveled by car when dry.
Earth Science Lesson
Monument Rocks, as well as nearby Castle Rock, and numerous sandstone bluffs in the area are today collectively known as the “Badlands of Kansas.” The region is also known as the source of some of the best Cretaceous marine fossils that have been found anywhere in the world. Beneath these bluffs and outcroppings lie thousands of feet of marine sediments that have provided paleontologists with a wealth of fossils and the remains of extinct animals.
A number of fossils, including fish bones, turtles, oyster shells, swimming reptiles, birds, coral, dinosaurs and sharks teeth can be seen at the nearby Keystone Gallery, the Fick Fossil and History Museum in Oakley, and at the Sternberg Museum in Hays, Kansas. According to locals, after a heavy rain, the area still smells like an ocean bay.
Today, it is hard to imagine that this flat, arid, cactus and buffalo grass prairie was completely covered by water, yet these awe-inspiring rock outcroppings tell a different story. The arches and buttes of Monument Rocks is spread out over ten acres and its history stretches beyond the prehistoric period into the more recent past, when the Cheyenne, Arapaho, Kiowa, Sioux, and Apache Indians utilized this area as hunting grounds when the buffalo and other game were plentiful here.
The Legend of the Arch
One of the most significant and most photographed sites at the landmark is the Keyhole Arch, which local lore says was started when someone was shooting at the rocks many years ago. When a bullet penetrated through a thin spot, the hole began and locals have watched it expand through the years. As it continues to widen, at some point, the top of the arch will collapse, leaving fragile spires behind.
What is a natural arch?
Definition: A natural arch is a rock (not ice, soil, etc) exposure that has a hole completely through it formed by the natural, selective removal of rock, leaving a relatively intact frame. The rock must be mostly exposed (ie not buried). The arch must have formed naturally, and not by some man-made process. Typically an arch will be formed by erosion, or volcanic activity.
Natural arches are almost always formed from water erosion around a softer rock base. Sometimes wind erosion can also cause an arch to form.
A diagram showing the sequence of arch formation.
- Deep cracks penetrate into the rock layers.
- Erosion wears away exposed rock layers and enlarges the surface cracks, isolating narrow walls, or fins.
- Alternating frosts and thawing cause crumbling and flaking eventually cut through some of the fins.
- The resulting holes become enlarged to arch proportions by rockfalls and weathering. Arches eventually collapse, leaving only buttresses that in time will erode.
Logging Tasks
To log a find for this Earthcache you must answer the following questions.
- Do you think the Arch was created from water erosion, or wind erosion?
- Using your answer above, and your observations of the area, do you believe that the Arch is stable?
- Do you believe the legend about this arch could be possible with what you now know?
- Post a photo of yourself or a proxy at GZ (Include in your online log).
References
- Weiser, Kathy (2020), Monument Rocks, Kansas - Pryamids of the Plains. Retreived from https://www.legendsofamerica.com/ks-monumentrocks/
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World Landforms (2015). Natural Arch. Retrieved from http://worldlandforms.com/landforms/natural-arch/
