Walking on Volcanic Domes in the Salton Sea Area
- Steve
- Oct 21, 2021
- 3 min read
The more I explore the Salton Sea area, the more interested I become in this strange and exotic location. For a primer on the Salton Sea, be sure to check out the main blog by clicking Salton Sea.
Today, we traveled to Obsidian Butte, part of the Salton Butte complex. The five Salton buttes are lava domes created by viscous magma that emerged from an estimated 820-foot-wide volcanic vent along the southeastern edge of the Salton Sea. The magma's high viscosity prevented it from flowing far, causing it to accumulate around the vent. Obsidian Butte resulted from this lava flow and is estimated to be 2,000 to 3,000 years old. This volcanic dome is composed of pumice and black obsidian.
We traveled along the dirt road from the base of the butte toward the shoreline. The butte has been heavily quarried, altering much of its original appearance. Nevertheless, there are piles of rock debris and obsidian outcroppings scattered throughout the area.
As we entered the region around the butte, the obsidian flow appeared endless. The butte was created by effusive eruptions, a type of volcanic activity where lava continuously flows out of a volcano or volcanic vent onto the ground, unlike explosive eruptions such as that of Mount St. Helens.
What is obsidian? Obsidian is an igneous rock that forms when lava, moving slowly, cools so quickly that atoms cannot organize into a crystalline structure.
We climbed over several flows before making our ways onto the shoreline.
We discovered some small obsidian pieces that looked like volcanic glass with a smooth, dark surface, while others displayed a more banded look.
Large outcroppings on the beach were covered with salt and sediment crusts, remnants from when the lake's water levels were higher.
Until recently, it was believed that the Salton Buttes last erupted 30,000 years ago. However, new evidence indicates that the most recent volcanic activity took place between 2,000 and 3,000 years ago, making them the youngest volcanoes in California. Since the USGS classifies any volcanic eruption occurring within the last 10,000 years as an 'active volcanic area,' the California Volcano Observatory conducts investigations and monitoring of the Salton Buttes.
Obsidian Butte and the other Salton Buttes (North Red Hill, South Red Hill, Mullet Island, and Rock Hill) are situated above the boundary between the Pacific Plate and the North American Plate. Beneath the surface, these plates are diverging, creating a spreading center. As they separate, magma from deep within the Earth rises to fill the resulting gap. This substantial magma body likely caused the effusive eruptions. Currently, geothermal power plants exploit this area, known as the Salton Sea Geothermal Field.
The geothermal source located beneath the Salton Sea heats brine situated 1.0-1.5 miles below the earth's surface to a temperature of 680°F. This extremely hot brine serves as the energy source for the geothermal plants, which are regarded as having one of the greatest geothermal potentials globally. These plants generate enough energy to supply power to as many as 325,000 homes.
Near the Salton Buttes, there is a field of small mud volcanoes or mud domes. The mud from these volcanoes is created when hot water, heated deep beneath the Earth's surface, mixes with underground mineral deposits, forming a mud slurry. This slurry is pushed upwards through a geological fault or fissure. The temperature of any active mud volcano generally remains quite stable and is significantly lower than the typical temperatures of igneous volcanoes, ranging from about 36-212 °F. Unfortunately, the area around the field was marked with 'No Trespassing' signs, preventing us from getting closer.
I'm definitely going to plan a second trip to the buttes. Once again, the more I learn about the Salton Sea area the more excited I become to plan future visits.
For other Salton Sea adventures, click on the hyperlinks below.
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