Falling boulder sparked Utah wildfire

CASTLE DALE — Investigators say a Utah wildfire that burned more than 800 acres in Emery County sparked when one massive boulder hit another.

Utah Division of Forestry, Fire and State Lands spokesman Jason Curry called the conclusion on the cause of the Lighthouse Fire "a rare one."

Curry tells the Deseret News a boulder the size of a refrigerator fell 800 feet from a cliff face on July 18 and bounced several times before crashing into a boulder the size of an SUV.

Investigators say the impact created "pressure friction" so hot that it ignited grass and brush nearby.

The fire was contained four days later.

The Lighthouse Fire was in Range Creek, which is known for prehistoric Native American archaeological sites. None of those sites has been reported damaged.