Tag Archives: Little Rock

Geo-pic of the week: “The Great Little Rock Silver Rush”

 

Argentiferous galena enhanced

In September of 1982, this 800 lb. boulder was excavated by a backhoe operator during construction of the La Quinta Inn on Fairpark Boulevard (currently Day’s Inn), Little Rock, AR. Another worker on site recognized it as galena (ore of lead) and, wanting to score some quick cash, the finder began contacting local geologists, hoping to sell. Eventually, then State Geologist, Bill Williams, heard about it and sent another geologist from the Arkansas Geological Survey (AGS), Ben Clardy, to investigate. Clardy bought the boulder for $100 and the backhoe operator loaded it onto Clardy’s truck for transport back to the AGS office.

At the office, an engine lift was rented to remove it. The agency’s chemist, Gaston Bell, assayed a piece for silver, determining it contained 1 – 2 %, making it high-grade silver ore. Feeling he had cheated the seller, Clardy contacted him with the results but the seller was happy with the $100 deal. The State Geologist reimbursed Clardy and placed the specimen on display in the lobby of the AGS office.

News of the find spread quickly, as the story was picked up by local newspapers. Someone claiming to be the hotel property owner announced that the backhoe operator had stolen the rock and came to the AGS office demanding it back. It was now property of the state, but Bill Williams told him he could have it, as long as he could bring some large guys to carry it off; he didn’t want heavy equipment in the office lobby. The man left and never raised his claim to the rock again. A couple days later another piece was found on the property in the same mineralized pocket which was at the intersection of two quartz veins. The property owner took possession of that piece and sent it to Colorado where it was smelted and produced a substantial silver bar.

Around the same time, as the public became aware of the find, some midnight rock poachers began sneaking onto the property, after hours. Small chunks of galena appeared around town for sale, being marketed as “Little Rock Silver Ore”.

At least one silver company took an interest in the find, conducting a series of soil tests over several blocks surrounding the La Quinta property. They soon abandoned the effort due to the difficulty of mining in such an urbanized area. Results of their tests were never disclosed. Eventually, construction of La Quinta was completed, the lot was paved over, and thus ended the “Little Rock Silver Rush”.

The original 800 – pound chunk is still on display in the lobby of the AGS office in Little Rock. Part of the other piece, which was not melted down, was displayed in the lobby of the La Quinta Inn on Fairpark Boulevard before the property changed hands.

Based on written correspondence with Michael J. Howard

Geo-pic of the week: Pinnacle Mountain

Pinnacle closeup edited (1)

This is a picture of Pinnacle Mountain – one of several steep-sided hills up to about 1000 feet tall, located at Pinnacle Mountain State Park, northwest of Little Rock, Arkansas.  Though its appearance may be misleading and its origin is debatable, Pinnacle Mountain is not a volcano!

What’s intriguing about Pinnacle and the smaller nearby hills is that they’re sandstone lenses surrounded by shale.  That, from a geologic perspective, is difficult to explain since sedimentary rocks are suppose to form in layers, not lenses or blocks.  This has led geologists to a variety of interpretations for their origin ranging from giant undersea landslides, to sand that got trapped in the empty gouges left by large undersea landslides, to beds of sandstone caught up and scrambled with shale beds along huge thrust faults.

Whatever their origin, because they are sedimentary rock and contrary to some satirical publications I’ve seen circulating online, they are not volcanoes and they are not going to blow up!

Geopic of the week: Arkansas Bauxite

 

bauxite enhanced

Pictured is a piece of bauxite, a sedimentary rock for which the central Arkansas town of Bauxite is named.  It’s also the principal ore of aluminum.  At times in the past century, Arkansas bauxite was the source of as much as 90% of the aluminum produced in the US.

Bauxite is a chemical sedimentary rock that formed in Arkansas from weathering of igneous rock.  During the Eocene (55 – 34 million years ago), North America was nearer the equator, and the tropical climate concentrated aluminum in rocks exposed south of Little Rock.

Following WW2, production of aluminum from Arkansas bauxite declined due to availability of rich international ores.  Mining of bauxite for aluminum ceased altogether in the state in 1981, though there is still a significant quantity of reserves.

 

To see more views of Arkansas Bauxite, click here

Geopic of the week: The Maumelle Chaotic Zone

Chaotic zone

This is a picture of sandstone and shale of the Maumelle chaotic zone that outcrops along highway 10 west of North Little Rock, Arkansas.  The Maumelle chaotic zone is part of the Jackfork Formation which forms the bedrock around much of the Little Rock area.  The chaotic zone is called that because of the disarray the rock is in there.  In the example above, broken blocks of sandstone are interspersed with disorganized shale beds that have been rolled, squashed and otherwise deformed (rock hammer at center is for scale).  The rocks weren’t deposited this way but were originally organized into horizontal beds on a deep-water ocean slope.  Before they could be hardened into solid rock, the slope failed and the beds were transported down hill in a massive submarine landslide. 

 

Note:  Other interpretations for this zone have been proffered.  The author of this blog prefers the above interpretation.

 

For more views of the Maumelle chaotic zone click here

Geopic of the week: La Petite Roche (Little Rock)

La Petite Roche07

Pictured above is about all that remains exposed of the rock outcrop that is the namesake of the capitol of Arkansas, La Petite Roche or The Little Rock.  The outcrop was given its name by early french explorers to the area who first arrived in 1722.  Though unimpressive in stature, it is notable because it is the first exposure of solid rock that one sees when navigating up the Mississippi and Arkansas rivers, starting at the Gulf of Mexico.

The geologic explanation for this is simple;  The land between New Orleans and Little Rock Arkansas along that route is in the Mississippi River Valley, where the bedrock is buried beneath river-lain and wind-blown sediment.  The city of Little Rock straddles the boundary between the lowlands of the Mississippi River Valley and uplands of the Ouachita Mountains, which stretch west well into Oklahoma.  Therefore this little sandstone and siltstone outcrop marks that physiographic boundary. 

If you boated all the way from New Orleans to Little Rock without seeing a single rock you would probably be impressed by it too.