Peffley is a likely candidate for the origin of Pethley.
Many Mennonite Peffleys and Pefleys are in the area.
Both the Pefley and Peffley as well as teh Peffly lines are common to the descendants of Nicholas Peffley, arriving in 1729 from theGermany area known as the Palatinate. arrival was August 29, 1729 at Philadelphia on a ship called MORTENHOUSE.
This family may be researched through a book published in 1938 by May MILLER FROST and Clarence Earl FROST, cal;led Peffley: Peffly and Pefley families in america.
Also a Peffley mail list is on rootsweb, where researchers share research results, and a Peffley family association website is there also.