This EarthCache is located along the Needles Highway near Laughlin, within the Big Bend section of the Colorado River, on the west bank within a small sliver of Nevada. Visitors to this location can observe a series of shallow cavities, holes, and small caves that have formed along exposed sedimentary outcrops. Unlike limestone caves formed by chemical dissolution, these features are sculpted from relatively young, weakly consolidated fluvial sediments deposited by the Colorado River during the late Cenozoic, primarily in the Pleistocene epoch. Geologists identify much of these deposits as part of the Chemehuevi Formation (110,000 to 90,000 years ago), which consists of layered sands, silts, clays, and occasional gravels. These sediments accumulated over time as the river migrated across its valley, depositing coarser materials within channels and finer silts and clays on the floodplain. Horizontal bedding planes can often be seen, recording successive episodes of deposition during past floods.
Extent of ancient lakes and fluvial deposits from the Colorado River shown in blue.
The holes and small alcoves visible along the highway are formed primarily through the combined action of wind and water erosion. Sporadic but intense desert storms produce surface runoff that scours the softer layers of the sediments more rapidly than the harder or coarser layers, gradually widening cracks and hollows into the cavities you see today. Strong winds carry sand and dust that act as a natural abrasive, slowly sculpting the surfaces and enlarging depressions over time. Minor temperature fluctuations in the desert environment can also contribute by loosening grains through repeated expansion and contraction, making it easier for wind and water to remove material. The result is a landscape of irregular cavities and shallow caves, often aligned along bedding planes or zones of weaker material.
When observing the site, notice how some layers erode faster than others, creating scalloped and hollowed surfaces. Tiny runoff channels may lead into the cavities, further accelerating the erosion process. These formations provide a clear example of how mechanical weathering, driven by natural forces like wind and water, can shape sedimentary landscapes even over relatively short geological timescales.
Works Cited
https://www.researchgate.net/figure/Regional-map-showing-the-relationship-of-Cottonwood-Mohave-Chemehuevi-and-Blythe_fig1_325730119
http://geobytesgcse.blogspot.com/2007/08/coastal-erosion-landforms-features-and.html
https://www.usgs.gov/publications/overview-chemehuevi-formation-along-lower-colorado-river
https://www.usgs.gov/publications/timing-and-geometry-chemehuevi-formation-reveal-a-late-pleistocene-sediment-pulse
https://ngmdb.usgs.gov/Geolex/UnitRefs/ChemehueviRefs_4982.html
TO LOG A FIND ON THIS CACHE YOU MUST ANSWER ALL THE QUESTIONS BELOW. YOU CAN CONTACT ME THROUGH MY EMAIL OR THE GEOCACHING MESSAGE CENTER TO SEND YOUR ANSWERS. ANY INCORRECT ANSWERS MAY RESULT IN A CLARIFICATION RESPONSE FROM ME.
1. "Big Bend of the Colorado - Wind Caves" on the first line of your email AND list all geocaching names of your party so I can match your answers to them. If you all want to learn something, I would prefer each cacher send me individual emails in the spirt of earthcaching.
2. Take a photo of you (or your signature item if you don't want to show your face) with the wind caves in the background from the road. This photo MUST be attached to your "found it" log.
3. Describe the rock or sediment you see at the site. Is it mostly sand, silt, clay, gravel, or a mixture? How well cemented or loose does it appear?
4. Examine one of the cavities or holes along the outcrop. Does the cavity appear to have been carved more by wind, by water, or by a combination of both? Explain your reasoning based on what you see (e.g., rounded edges, smooth surfaces, small runoff channels).
5. Do you see any evidence of small runoff channels or water flow near the cavities? Describe how these features may have affected the erosion process.
6. Think about the desert climate here. How might occasional rainstorms, strong winds, or high air tempuratures work together over time to sculpt the features you see?
7. If you could visit this site in 100 years, how do you think the cavities might change? Would they grow, shrink, or remain largely the same? Why?