Farmers puzzled as land tumbles into sinkholes

Kenneth Heard
Arkansas Democrat-Gazette

GOSNELL -- It's not the dropping prices of cotton, soybeans and other agricultural products that have northern Mississippi County farmers scratching their heads.

It's their property that's dropping -- literally.

Chunks of land, ranging from 3-foot circles to 20-foot-long trenches, have collapsed in areas north and northeast of Gosnell.

The sinkholes range in depth from 1 foot to more than 6 feet. Scientists say they don't know why this is happening.

"It's erie," said Marion Haynes, an assistant at the Arkansas Archeological Survey's Blytheville station. "We don't really know what they are."

Theory No. 1: The sinkholes could be the result of a statewide drought.

Arkansas' average rainfall this year is more than 11 inches below normal. As a result, farmers have relied more on groundwater, which may cause the sandy Delta soil to shift and resettle.

Small caverns form under the topsoil and may eventually cause the collapses, said Claudine Payne, the Blytheville station's archeologist.

Theory No. 2: the sinkholes could be earthquake-related.

Situated in the center of the New Madrid seismic zone, the sinkholes could be caused by subsurface earthquakes, though scientists say they won't push the panic button -- not yet anyway.

"It's not related to any recent ground motion," said Joan Gomberg, a research geophysicist with the University of Menphis' Center for Earthquake Research and Information. "We would have monitored any movement."

Theory No. 3: Advances in farm machinery have made equipment heavier and more susceptible to falling through the ground. That's a stretch, area farmers say.

Landowner Rachel Gaines thinks toxic chemicals may have leaked into the soil from the nearby former Eaker Air Force Base.

"I blame it on chemicals close to the base," she said. "They brought dirt in from over there, and we can't hardly grow anything on it now."

The base has been closed since December 1992, and the U.S. Air Force conducted extensive environmental studies at the time of the closing. No chemicals were detected.

No matter the cause, Gaines is irritated by the sinkholes. Part of her prized flower garden has fallen in.

So far, Haynes has inspected more than 25 holes. Many are just north of the former air base's largest runway. Others have appeared along the Mississippi County Road 38, which bisects the many cotton fields between Gosnell and Yarbro.

Haynes has asked residents to report any collapses they find. He thinks there are at least 100 in northern Mississippi County.

Gaines said she noticed two large sinkholes in her yard after a rare day of rainfall in November.

One hole on Gaines' farmland is about 20 feet long. The ground dropped about two feet along the edge of a cotton field. The other hole, which devoured her flower garden, passes through a line of small trees to County Road 38. it reappears briefly on the other side of the road.

Farther down the county road, Tommy Burnham's large truck bed sits in a hole with a 10-foot diameter in his front yard. The bed sank about 3 feet.

Geologists have been summoned to study the holes, Payne said.

"We're archelogists," she said. "We can tell you when something happened before." But this is unsettling."

There are geological factors unique to the area to consider.

Northeast Arkansas contains what scientists are calling "world class" evidence of sand geysers, or "sand blows."

Much of the areas topsoil is spotted with these large light circles of sand. During a violent series of earthquakes along the New Madrid seismic zone from Marked Tree northeast to Cairo, Ill., in 1811-1812, the ground turned to liquid, according to some accounts.

Witnesses told a horrifying tale of geysers of sand shooting 20-30 feet into the air. Pressure from under the ground turned fertile fields into desertlike land from Marked Tree to Sikeston, Mo.

The sand, which can be clearly seen from an airplane, constantly shifts.

Martitia Tuttle, a geologist with the University of Maryland and an expert on sand blows, speculates that the area's geological composition could cause the collapses. When wet, the Delta sand expands. When dry, it contracts causing land above to split and cave in, she said.

"We really don't know yet," she said. "We've only dug down five feet or so. We need to go much further to really tell what's going on. It's still a mysteryt to us." 

While the sinkholes don't appear to be any indication of impending earthquakes, Haynes said there is an urgency to conduct more studies.

"We're sitting in earthquake country. You never know."

Gaines perfers not to talk too much about the sinkholes. Part of her land collapsed during the 1930's and she has kept a slightly superstitious attitude since.

And, she has a flower bed to repair.

Still, Gaines says she has a more economic reason for keeping quiet about the sinkholes.

"If everybody finds out about this, the value of our land might go down."

This article was published on Sunday, December 12, 1999