A Glimpse Back in Time: Sandstone Monolith
A Note of Encouragement:
Welcome to the Klamath National Forest Earth Cache program! Most of the Earth Cache locations are located away from established recreational trails and roads. Visitors are strongly encourages to check with Ranger District offices for information on current road and trial conditions before visiting sites, and be prepared for cross-country hiking.
Layered clothing, water, and appropriate maps are essential when traversing the remote, rugged landscape of the Klamath National Forest. Please be aware of wildlife and poison oak while visiting Earth Cache locations in the forest and use caution when traveling on narrow winding forest roads.
Location Information: UTM 10 T 0524777 4652857
This Earth Cache location is located in the Happy Camp/Oak Knoll ranger district of the Klamath National Forest. However, much of the area surrounding this location is privately owned. When visiting the site trees marked with red spray paint indicate the boundary between U.S. Forest and private land.
Directions: From Interstate-5 (you will be in Oregon) take exit 6 going south on Old highway 99 S. Turn right onto Mt. Ashland Ski road (Primary Forest road 20) and follow for 1.3 miles until you reach Colestin road. Take a slight left onto Colestin road. Take Colestin road for 2.5 miles and then turn left onto NF 40S06*. Stay on 40S06 for 10.2 miles, and then make a sharp left onto 41S06. Take 41S06 for 1.6 miles and make a hard left onto 41S05 (may not be labeled on all maps). Stay on 41S05*, passing Forest roads 41S08 and 41S05A. The sandstone monolith is located off of 41S05, so you will need to use your GPS to find it.
*Due to road conditions, high clearance vehicles are suggested.
Geological Information:
The Klamath Mountains 145 to 66 million years ago looked very different from today. Only sections of this range had formed. There were volcanoes as
well but not the Cascades of today (Mt. Shasta is only 593,000 years old). This period is mark by a significant rise in sea level which led to the deposition and creation of the Hornbrook Formation.
About 145 to 66 million years ago the area around this EarthCache site was under an ocean (Figure 1)! It is from this ocean environment that the Hornbrook Formation, a unique compilation of marine deposited sandstones, conglomerates, siltstones, and shale, forms. Today the Hornbrook Formation’s various units tell the story of a shallow sea including fluctuations in depth and energy.
The sandstone monolith comes from a section of the Hornbrook Formation that depicts a marine shelf environment. It illustrates the transition from a wave-dominated environment with hummocky cross-stratification (Figure 2), to a low-energy environment in its massive beds. In the area, changes in the sandstone composition are seen through weathering; some rocks are more weathered than others or have surficial discoloration.
After 145 million years the Hornbrook Formation reveals its secrets in unusual features in the landscape. This EarthCache illustrates this by highlighting a monolith. A monolith is a single massive rock that is usually exposed by erosion. This particular monolith is sandstone with a shape resembling a mushroom. The top and bottom sections of the monolith exhibit different features reflecting the particular depositional environment.
The Hornbrook Formation enables us to imagine the Earth and the Klamath Mountains as they were over 100 million years ago!
Logging Requirements and Questions:
- The text “GC44JFC” on the first line
- Number of People in group
- The date or season
- What are the differences you notice between the top and bottom section of the monolith? In weathering? In grain size? In composition?
- Explore the area. Can you find any other cool/interesting formations? Describe what you find.
Contacts:
Happy Camp/Oak Knoll Ranger District
63822 Highway 96
Happy Camp, CA 96039
(530) 493-2243
Fax (530) 493-2212
TDD (530) 493-2894
Klamath National Forest
Supervisor's Office
1711 South Main Street
Yreka, CA 96097-9549
(530) 842-6131
FAX (530) 841-4571
TDD (530) 841-4573
Resources:
Boggs, S. (2006). Principles of sedimentology and stratigraphy. (Fouth ed.). Upper Saddle River: Pearson Prentice Hall.
Elder, D., De La Fuente, J., Bell, A., Mikulovsky, R., Stevens, M., & Levitan, F. U.S. Department of Agriculture , National Forest Service. (2012). An Introduction to the Geology of the Klamath, Mendocino, Shasta Trinity, and Six Rivers National Forests in Northwestern California.
Nilsen, T. U.S. Department of the Interior, U.S. Geological Survey. (1993). Stratigraphy of the cretaceous hornbrook formation, southern oregon and northern california. Washington: United States Government Printing Office.
Additional Information:
If you are interested in seeing other geologic sites in the Klamath National Forest please visit us at http://www.fs.usda.gov/attmain/klamath/specialplaces for more information.*
*Not all locations are Earth Caches.
If you would like to suggest a site/location in the Klamath National Forest for Earth Caching please send us an email at knfearthcache@fs.fed.us
