Joyce Y. Beddell is charged with aggravated and simple assault, recklessly endangering another person and endangering the welfare of a child.
She is being held in jail in lieu of $10,000 bail.
Police said that Beddell discovered her granddaughter in bed having sex with a neighborhood teen girl.
The neighboring teen ran when Beddell entered the room, according to police, and escaped the elder woman's wrath.
The granddaughter was not so lucky. Beddell allegedly took a cane and then a belt to the 16 year old. She then forcibly took the girl from the house.
Neighbors saw Beddell taking the limping granddaughter to the other girl's home where she informed that girl's parent of the affair.
Police say Beddell then took the 16-year home where she proceeded to beat her again.
The 16-year old suffered serious bruises to her buttocks and legs.
Police were called to the house to investigate a report of child abuse. It is not clear who filed the abuse report.
The teen is being treated in hospital for unspecified injuries the Reading Eagle reported.
Beddell told police that she had done nothing wrong, the paper reported, and said she should be allowed to discipline her granddaughter as she sees fit.