On the night of August 19, 1779, there occurred on the south side of the North Mountain about ten miles northwest of Carlisle a geological phenomenon that eventually drew the attention of the astronomer David Rittenhouse, Dr. Benjamin Franklin, the Secretary of War, and the president of Harvard College, and was described both in private letters among these and other men and also in the published proceedings of the second oldest learned society in the United States.
We report here that evidence for the 1779 Carlisle Deluge still exists. In the Summer, 1996 issue of Cumberland County History, Whitfield J. Bell described what he called the Carlisle Deluge. Bell used primary sources, mainly a letter from David Rittenhouse to Benjamin Franklin, to describe how, on the night of August 19, 1779, a thunderstorm with copious rain opened a gash on the south side of North (Blue) Mountain east of Flat Rock and northwest of the present Bloserville. Rocks and trees were carried down the mountain.
While not one of the earliest municipal components of Cumberland County, Frankford Township dates back to the 18th century. It was created from West Pennsboro Township in April of 1795, by the County Court. The court records tell us: