Langell Valley, and the other valleys in the Klamath Basin were once the bed of what is called Lake Modoc. The lake covered what is now known as the Langell, Poe and Sprague River Valleys, Yonna and Swan Lake Basins. The remnants of this great lake exist in today’s Upper and Lower Klamath and Tule Lakes, as well as the Lost, Sprague and Link Rivers.
The overall length of Lake Modoc was 75 miles and covered more than 1000 square miles. Surprisingly, there is almost no elevation change through the entire lake bed. The lake must have been a shallow, slow moving body of water prone to heavy sedimentation, just and Upper Klamath Lake is today. Deposition of sediment provided the soil that farmers in the area depend upon today. Adding to the mix are large quantities of ash, cinders and pumice from ancient volcanoes and vents.
Surrounding the lakebed, are large hills, ridges and mountains. These were formed in the past by block faulting and igneous activity. The ancient shoreline of Lake Modoc was formed by these protrusions. Over the past 10,000 years, the climate changed to the current semi-arid climate and lead to the gradual evaporation of the lake. This process continues today, accelerating due to the dredging of Link River.
Today’s Langell Valley lies at an elevation of between 4,120 and 4,200 feet. It is roughly 20 miles long and at most 4 miles wide. The largest feature of the valley is a hill known as “Dead Indian Hill” and is 1.5 miles long and .75 miles wide. The Lost River flows through the valley, at a very slow rate due to the general lack of elevation change. During the hot summer months, the river has been known to disappear as it once flowed underground in the southernmost part of Langell Valley.
Parking is available at GZ alongside the public road in an ample pull off area
1. What is the GC and name of this cache?
2. What is the color and texture of the rocks that form the riverbed and banks?
3. What process mentioned above is most likely the cause of this coloration?
4. What geologic process mentioned above caused the markings on the rocks along the riverbank?
Please feel free to include a picture of yourself or the scenic views offered at this locale. Do not include your answers in your log, even if in code or through hints.
