They say the woman was hiking with several others in the Kelly's Run Nature Preserve in Martic Township when she fell Sunday afternoon.
A companion hiked out to an area where cell phone service was available to call 911.
Tony Williams, assistant chief of the Rawlinsville Fire Company, says the woman was unresponsive when rescuers reached her, and efforts to revive her failed.
He says dozens of firefighters responded, battling heat and treacherous terrain.
Williams says rescuers had to use ropes and pulleys to remove the body.
The victim is not yet being identified.