There is protected turnoff with an informational panel that talks about Life in a Dry Lake. The difficulty is in identifying the alluvial fans and discerning the somewhat minor differences in their geomorphology (their shape). The terrain can’t be any lower, you don’t even have to roll the windows down if you park in the right spot.
Toward the north is Clark Valley with the Santa Rosa Mountains on the east side of the valley. Between the valley and the mountains is the Clark Fault.
Along this section of the fault, there is quite a bit of vertical movement. Relative to each other, the valley is sinking while the mountains are being pushed up. This has resulted in the steep mountain faces you see.
A series of alluvial fans have been built up across the eastern edge of the Clark Valley covering the fault. However, not all of the alluvial fans are the same age. Movement along the fault allowed some of the fans to start building up long before others started. The older (mature) fans tend to have extended further from the mountains than the younger ones. Additionally the older fans are not as steep.
This difference is easily explained by the added time the older fans have had to develop. Much more sediment has been deposited on the face of the older fans and that added material has to go somewhere. It build out the base of the fan extending it further from the steep slopes of the mountains and creating a more gentle slope. The younger fans have remained close to the mountains since not as much material has been washed out of the mountains to build out the base of the fan. Consequently the fan is relatively steep.
Logging requirements:
Send me a note with :
- The text "GCZBYV Alluvial Fan Ages" on the first line
- The number of people in your group.
- Based on the general description of young and mature alluvial fans, send me an e-mail giving the relative ages of the alluvial fans along the eastern edge of Clark Valley. i.e. the fans closer to the highway or to the east are (insert relative age) than the fans further up the valley running north. I want you to stand looking north and ignore the small hills in front of the mountains. Include the characteristics that helped you make your determination. (Do not post pictures that show the fans)
The above information was compiled from the following sources:
- Source: Geology of Anza-Borrego: Edge of Creation, Paul Emeika and Lowell Linsay; Kendall/Hunt Publishing Company, Dubuque, Iowa, 1992