Vaden Holiday Rock was my grandfather and Perry Sumner Rock was his father. I have geneology on the Rock line going back to Frederick Rock and Catharine ?? in Bedford County Pennsylvania around the 1840s.
I know very little about the sumner line or the Holiday line.
I am unsure of Perry Rock's profession but do know that he spent some time in Alaska as well as Jackson WY. I will email some of our family historians and see what additional information they have.
Also here's a website about the Rock family in Pennsylvania.http://www.rockfamilygenealogy.com/Rock_Frederick_Catherine....