Thursday, August 18, 2011

Black Rock Canyon Volcano and A 3.9 Mag Earthquake at Earthquake Swarm near Hawthorne, Nevada

An overall view of Black Rock Canyon, Joshua Three National Park, near Yucca Valley, CA. This small area on the West end of the the National Park is a geologist's wonder zone, and one filled with mystery. As you can see, the plant life is rich and abundant, and this may be due to the complexities of the rocks themselves, and the minerals they carry.

Robert, a first grader and budding geologist (already a rock hound exponential!) points out the complex layers of quartz rich magmas mixed with mica rich host rock, believed to be re-melted gneiss. Magma is the hot semi-molten material that eventually slowly cools, creating crystals and granite related rocks. Host rock can be ancient gneiss and schist, recent sedimentary rock such as sandstone, or any other older rock in which the magma penetrated.

Robert, our young rock hound, is pointing out a band of quartz, the white narrow ribbon you see, as it streaks across it's host rock. These quartz veins can occur in various conditions, and often the host rock or magma derived rock cracks due to cooling, and magma fills in the cracks, along with water, this generating crystals and coveted metals. This is theory at this point in time, but mostly accepted.

A view from Black Rock Canyon over Yucca Valley, CA, and her surrounding high desert communities. You are looking north up along a land based rifting zone that will, in time, open up and create an narrow sea, extending the Sea of Cortiz northward.

Details of the sheeted complex that makes up the Little San Bernardino Mountains, which much of Black Rock Canyon lies in. The banded layering is believed to be flattened intrusions of magma and semi-melted or at least metamorphized original host rock.

Young Robert points out the mica rich layers within quartz rich layers of rock. These rocks have a story to tell. It's about being melted or semi-molten rock mixing with other rock, thus this kind of banding.

Let me just add in a heart warmer. Here is my pal, Rebel. He is an energetic and sensitive German Short Hair Pointer. He helps me meet other people, especially those probing earth movements, and he warns me of rattlesnakes and other hazards in the field. I must remind you that my Head Canary remains as my Assistant Seismologist.

There seems to be a reemerging earthquake swarm near Hawthorne, Nevada. That quake swarm never really stopped, but it indeed slowed down quite a bit after very intense earlier part of the earthquake sequence. Today, with a 3.9 mag earthquake, along with others around it, happened. The earthquake sequence seems to be picking up pace. Here is a link from the USGS, were the map shows the highy localized quake swarm.

Also, today while walking my dog Rebel, I ran into a local woman in Pioneer Town. We started talking about animals, and then how they behave just before an earthquake, and that led us really sit down and discuss earthquakes. That led to her talking about her experience riding through the Landers earthquake.

Here is a very interesting note what she mentioned: Right after the Landers earthquake, Cal Tech went to Black Rock canyon, near Yucca Valley, CA. They went to the camp ground there and told everyone to leave right away. Apparently there is a brand new volcano that emerged about the time of the Landers earthquake. According to this local woman, that volcano has been growing rapidly since.

That makes sense to me, for when you have a large earthquake, and if there is a magma body nearby, you run the chance to upset the magma chamber, thus an eruption.

The entire area extending from Yucca Valley, to 29 Palms, Landers and Joshua Tree-This area is riddled with the The Young Volcanos. System. A few towns sit right on a transform fault that is at a near right angle to the parallel faults of the region. Small cinder cones and young volcanoes love to emerge at the point where a transform fault meets the main rifting fault.

I can't confirm the existence of Black Rock Canyon Volcano until I read up on it and visit the area. I have been to Rock Rock Canyon itself, and it is a very interesting location, where you can see how various magmas had interacted with surrounding rock in what's called the Little San Bernardino Sheeted Complex. This series of magma intrusions happened far underground, perhaps 12 miles down, over hundreds of millions of years. Up lifting from the San Andreas fault and erosion cause them to be exposed.

The area is just north of the San Andreas fault, and it very near to the complex of volcanos, including Pipes Canyon Volcano.

1 comment:

  1. I lived just north of Machris Park in the main water shed area there is a hill in the center of the shed at the bottom of San Andreas Rd The hill is where we had our house. The seismologist came from Cal Tech and camped on our property for a week running tests. He told us to leave as quick as we could for the tests he had run showed a crack 5 miles deep and had said that the earthquake had cracked the mantle. We saw liquifaction of the soil during the quake which I believe only happens at an 8.0 magnitude. My Cadillac was parked on hard pan before the quake and was buried to the frame after hence liquifaction. We were jumping over cracks which were opening and closing as we ran down from the top of the hill. Pretty extreme experience. I believe the earthquake was downgraded.