Black Speck in Grass Offers Expert a Possible Clue to Origin of Flames

EXETER, Calif. —  Somewhere in 30 acres of burned grassland lay--maybe--a tiny remnant of a spark shot from an engine’s exhaust.

It was state Department of Forestry fire investigator Mike Weger’s job to find it.

But the carbon particle, if it was there, was the size of a small grain of sand. The task appeared to be more difficult than looking for a needle in a haystack, but Weger knew where to look.

Vehicle Seen Before Fire

When firefighters were called, the blaze was burning a hillside above an orchard near California 198 between Lemon Cove and Exeter in Tulare County, 150 miles north of Los Angeles. A dirt road across the hill stopped the fire from spreading downhill. An all-terrain vehicle had reportedly been seen on the road before the fire started.

While fire crews stopped the blaze on the other side of the hill, Weger walked along the road, studying the way the burned grass lay.

“The grass falls back into the fire, pointing in the direction the fire spread from,” he said.

Beer cans also point the way. A can or rock is burned more on the side from which the flames came, Weger said.

There was one place at the edge of the road, roughly 4 feet in diameter, where the grass wasn’t pointing in any particular direction. Burned grass on both sides pointed to that place. The grass on the hillside just above pointed downhill.

“In fire parlance, this is called ‘the area of confusion,’ ” Weger said. “The fire burned this way, then that way, before the wind caught it.”

There was no cigarette butt or burned-out match in the area of confusion. So, Weger brushed the blackened ground with a magnet a little smaller than a blackboard eraser.

“The magnet picks up carbon particles,” he said.

A farm worker rode up on an all-terrain vehicle, and Weger inspected the exhaust. The rider said he hadn’t been on that road earlier. The vehicle did not have a spark arrester on its exhaust, but its tires did not appear to match tracks on the dirt road, Weger said, going back to his magnet.

‘I May Have Found One’

Then the find.

“I think I may have found one,” he said.

It was nothing more than a black speck, hidden in 30 blackened acres.

A laboratory analysis of the carbon particle could prove whether it came from a particular motorcycle, all-terrain vehicle or other equipment.

If a match can be made, the rider or operator of the equipment will be sent a bill for the cost of putting out the blaze.