An awesome view of the confluence of Deer Creek and the Sacramento River.
The Upper Sacramento River is that part of the river that lies above Shasta Lake. This section of the river is vigorous and swift-flowing, a classic mountain river racing through a deep canyon. However, the Upper Sacramento River can be further subdivided into more parts. Below Lake Siskiyou, the lone impoundment on the Upper Sacramento the river travels through a lush, narrow canyon. Above the lake the river has a wider flood plain for a brief duration before it splits off into its nascent forks, the South, Middle and North Forks of the Sacramento. Each of these forks lead to headwater basins high in the Trinity Divide. Where they all converge, there is a brief but beautiful and fascinating stretch of river.
The short segment of river where the tributary forks converge is a classic Klamath Mountains river. It flows through a flat plane filled with large rocks of a multitude of colors, hinting at presence of serpentine and peridotite and the complex geologic composition of the Klamath Mountains. Yet, unlike other rivers in the area, some unusual geology is made manifest here that offers an intriguing glimpse into the river’s past. This is most evident at the confluence of Deer Creek with the Sacramento. At this spot the river’s north bank is nearly vertical for 40 to 80 feet, a contrast to the more gentle slope that characterizes the rest riverbank. In this vertical section, layers deposited by previous floods are exposed. It is an unusual opportunity to see the river’s history made plain in the landscape.
The Cement Bluff above Bluff Lake.
Some similar examples are found elsewhere in the Klamath Mountains. These formations are referred to as “cement”. Given the aggregate in each layer, I think it is an appropriate description. The two most prominent formations of this type are the Cement Banks in the Trinity Alps and the Cement Bluff in the Scott Mountains, just north of Mount Eddy. Both are far more massive than the cement formations along the Sacramento River but the one along the river is the most accessible and easiest to examine up close. The other two, larger formations are also somewhat more mysterious since they are further removed from rivers that would flood. It is likely they are the result of glaciation rather than flooding.
Regardless of how the Sacramento cement formations compare to the larger formations elsewhere in the Klamaths, the geologic layers exposed along the river are fascinating in their own right. The added benefit of the river’s presence makes this area as delightful and beautiful as it is compelling.
Just upstream from the confluence is a good place to see layers stacked on each other. The river currently flows through the broad, boulder-filled field. It has been slowly washing away the rocks and digging a deeper channel. Above boulders is another layer of gray sand and smaller rocks. These were deposited during a large flood at some point in the past. Above this is yet another layer of red soil and more rocks, though many of these are not rounded nor exhibit as much evidence of having been tumbled in the water.
The same layers are visible just below the confluence with Deer Creek. The boulder layer is at river level while the gray and red layers are stacked above the water. Note that just above the rapids on the left, there are some larger boulders embedded in the soil.
From a prominent vista point above the confluence, the layers are more obvious. The river flows through the large boulder field. The gray layer stretches out just above the water and the higher cliffs are composed of red soil.
The best place to look at these layers up close is on the spit of land that lies between Deer Creek and the Sacramento. It is possible to climb up to the base of a massive cut bank and examine the rocks. Upon closer investigation one finds that the rocks are very loosely packed into the sand. They are easily removed from the aggregate layer. These rocks were washed down in a large flood and settled into the sandy deposits left behind. At a later date the red layer was deposited on top of this. I have no idea if any of these layers are a product of melting glaciers or if they were all flash floods of immense proportion at some time in the past.
Interestingly, these layers extend a short distance up Deer Creek as well. Not far upstream from the confluence, the creek flows through a small gorge it has carved through a sandy bedrock layer. Above that is the multi-colored rocks and then the red layer. Strangely, it almost appears as though the boulder layer and the gray layer have been reversed.
Back at the Sacramento, the process of flooding and erosion continue to shape the river’s passage. Over the last decade the river has widened it channel considerably at the confluence with Deer Creek. In June of 2011 I visited the spot and observed the massive amount of runoff from hot weather and an exceptionally deep snow pack. The river was split into 5 large channels, each of which would currently be considered the river’s full flow in its main channel. When I visited this year, I noticed for the first time that the (current) main channel was much wider and a number of trees have been washed away.
The arrows mark trees that are present in both pictures. Note the base of the dead ponderosa is adjacent to the river now but was set back quite a ways from the channel in 2011.
Note that in addition to the channel being wider and many of the trees washed away, the large ponderosa has died. I am not sure if the tree drowned or the impact of rocks washing downstream damaged its roots or if some other explanation explains its demise. It remains an intriguing landmark from which to measure the growth of the river’s channel.
This section of the Sacramento is my favorite part of the entire river. The cement formations and their corresponding layers never cease to amaze me and I love investigating the ever-changing terrain. It shocks me that there are no trails in this beautiful area, though that is not necessarily a bad thing. Nonetheless, it remains an area that warrants more exploration and offers great rewards to those who take the time to venture just a short way off the beaten path.