BAINBRIDGE, Ohio -- Farmer Dale Mark doesn't buy theories that aliens from outer space left the geometric designs etched into his Ross County soybean field.

Mark thinks it was the work of pranksters, and he wants them to pay him $1,200 for the damaged beans he can't harvest. He said he has no insurance to cover the loss.

Passengers in a private airplane discovered last week that the two acres of crops had been flattened into a series of circular designs. One surrounds a triangle, another resembles a peace sign, and a third looks like a bull's-eye.

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Some folks in town blame teenagers hoping to draw attention to their rural community 55 miles south of Columbus. Others welcome the mystery -- and theories that extraterrestrials or supernatural beings are responsible.

"I think it's people who've done it, myself," Mark said. "I really don't believe in aliens."

He says he's waiting to see whether anyone comes forward before filing a report with the sheriff's office. "I'd just like to find out who it is. I don't want them to do it again."

Mark's wife, Mary Ellen, suspects the culprits knew the area well because the design is on land that's difficult to reach from the road.

That's curious, she admits. "It does make you wonder, because there's no in or out."

Even the so-called experts on farm circles don't agree on what caused them.

Jeffrey Wilson of Dexter, Mich., and a team of independent researchers studied the formations this week and ruled out a hoax.

"The plants were all swirled down counter-clockwise, and several places were woven together," Wilson said. "Along the stems of soybean plants where the branches bend off, the leaf bases had been shriveled up and browned as if they had been subjected to some sort of heat damage."

"I think we're going to say that this one was authentic," he said.

But Miami University professor and physicist Christopher Church, who has studied such phenomenon in England, has a different explanation for many crop circles.

"When the patterns include words written in English and, in some cases, you have very complex geometric patterns, it seems pretty clear to me that people are doing it," Church said.

SLIDESHOW: Ohio Crop Circles

An Adams County woman was checking a soybean field for flood damage last month when she allegedly discovered crop circles.

The field is across the road from Serpent Mound. Those who have seen the circles said the design appeared to be pointing to the ancient Native American mounds and that the markings in the field and tail of the mounds are similar.

An independent crop-circle investigator visited the site and said the radiation levels and electrical and magnetic fields were higher inside than the land outside the design.