the Borden Grant was located south of Beverley Manor
Source: Library of Congress, Carte de la Virginie et du Maryland (1757)
In 1739, the colonial government authorized a 100,000 acre grant to Benjamin Borden. The land to be selected and surveyed was to be located south of William Beverly's grant, and would be clearly out of the area claimed by Lord Fairfax.
Borden was required to recruit 100 settlers within two years. He succeeded, and patented 92,100 acres. So many settlers were Scotch-Irish that the area became known as the "Irish Tract."1
The land was within the planned boundaries of Augusta County. The General Assembly chartered Augusta and Frederich counties, the first two completely west of the Blue Bridge, in 1738. The county courts were not appointed until there was a critical mass of settlers in 1743 (Frederick) and 1745 (Augusta). During Borden's two-year settlement period, Orange County had the only county surveyor west of the Blue Ridge.
1. Larry Hoefling, Chasing the Frontier: Scots-Irish in Early America, iUniverse, 2005, p.35, https://books.google.com/books?id=og7NJHT0PqQC (last checked May 22, 2018)