A nine-year-old eastern Iowa boy has died after following his dog over a cliff. Colonel Karl Kolz of the Linn County Sheriff’s department says the accident happened yesterday at Palisades-Kepler State Park west of Mount Vernon.The boy was with his 10-year-old brother and two adult neighbors who were walking their dogs in the park when one of the dogs got loose from its leash. The dog ran over an embankment, and the boy followed and apparently fell off a cliff, landing 40 feet below in the Cedar River.Colonel Kolz says the child was pulled from the water by one of his neighbors, and when the rescue crew arrived on the scene, they were unable to resuscitate the boy. Kolz says a cause of death has not been determined, but they believe the boy — identified as William Kurtis Owen-Wentz of Marion — drowned.