Otus the Head Cat

Reports of Pinnacle eruption greatly exaggerated

Steam vents from Pinnacle Mountain last Sunday, relieving any fears of a sudden volcanic eruption.
Steam vents from Pinnacle Mountain last Sunday, relieving any fears of a sudden volcanic eruption.

Dear Otus,

You can't imagine the panic that set in last week when word spread that there was going to be an imminent volcanic eruption of Pinnacle Mountain. Half my friends evacuated down the road to Malvern.

I had always thought that Pinnacle was nonvolcanic. Can you fill us in?

-- James Gregory, Benton

Dear James,

It was wholly a pleasure to hear from you and it is a further pleasure to put your mind at ease.

The first report of "an imminent threat" came from the Rock City Times, an online publication with a reputation for, shall we say, creative exaggeration.

Don't get me wrong. I find the Rock City Times highly amusing and frequently chortle out loud at its humorous take on the day's events.

However, the outlet brags on its very own cover page that it is "Arkansas' 2nd most unreliable news source." One must take anything reported by the Rock City Times with a grain of salt. Maybe several grains.

In the case of the "imminent volcanic eruption," the Times took a highly conjectural study from the U.S. Geological Survey and extrapolated a serious "worst-case scenario."

The Times quoted USGS official Helen Pike as saying, "Time to consider evacuation plans if you are in the Little Rock metro area. This will be a very violent volcano." Left out was the first half of her statement, "If this were to happen, it would be ..."

The USGS study was commissioned when there appeared to be a relationship between recent natural gas fracking in north central Arkansas and the disturbing increase in minor earthquakes in the area defined by Heber Springs, Fairfield Bay and Clinton.

Once thought to be safely out of the New Madrid seismic zone and the Mississippi Embayment Synclinorium, this area has been re-evaluated in recent years.

On Jan. 1, 1969, a tremor centered about 19 miles northwest of Little Rock near Houston cracked plaster in the capital city and moved furniture about in some homes. Trees and utility wires swayed throughout a wide area. The tremor was felt as far away as southern Missouri and western Tennessee.

This pointed to a heretofore unknown fault that runs directly beneath the Fulk Mountains, the most notable of which is Pinnacle.

You are correct, James. Pinnacle is technically nonvolcanic. The cone-shaped peak reaches an elevation of 1,011 feet above sea level and looms a majestic 756 feet above the adjacent flood plains.

First noted in literature in Thomas Nuttall's A Journal of Travels Into the Arkansas Territory During the Year 1819, the peak was first called Mamelle Mountain, a name commonly applied in the French-speaking parts of the world to any breast-shaped hill.

The name lives on in the Maumelle and Little Maumelle rivers and the nearby town and lake.

The Ouachita Mountains are part of a highly eroded late Paleozoic orogenic belt formed between the colliding Grenville and Yavapai-Mazatzal tectonic plates. They formed about 275 million years ago. Pinnacle is what remains of a once mighty mountain range after millions of years of erosion.

Untold thousands of Arkansans have made the trek up Pinnacle since 1822 and so far it has been a safe and uneventful adventure with a spectacular view waiting at the end.

However, USGS studies suggest that there is a previously dormant branch of the New Madrid fault that extends beneath Greers Ferry Lake and cuts southwest under Pinnacle, ending somewhere near Lake Balboa in Hot Springs Village. The suspicion is that natural gas fracking resulted in the recent series of earthquakes and caused a buildup of magma pools along the fault and deep beneath Pinnacle.

What the Times failed to report was that the USGS study speculated that the sandstone beneath Pinnacle was so honeycombed with stress fractures and fissures that if there was to be any volcanic activity, it would be simple steam venting that would ease the pressure and prevent any massive explosion and release of lava.

And that's precisely what happened last Sunday. As you can see in the photograph, the feared eruption of Pinnacle Mountain was, in fact, a rather innocuous release of steam over a four-hour period -- a spectacle that delighted onlookers, although park rangers kept the crowd back a safe distance as a precaution.

Other than a few singed turkey vultures and a panicked defluxion of the park's snake population, the trails are unharmed, and the USGS estimates hikers will have no volcanic worries for at least another 275 million years.

Until next time, Kalaka reminds you to always question what you read on the Internet. You never know who's vetting that stuff.

Disclaimer

Fayetteville-born Otus the Head Cat's award-winning column of humorous fabrication appears every Saturday. Email:

mstorey@arkansasonline.com

HomeStyle on 09/13/2014

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