
topography of Loudoun County (excluding Dulles airport...)
"
The highest elevation is 1,920 ft above sea level on Blue Ridge at the southwestern part
of the county,and the lowest elevation is 180 ft above sea level
along the Potomac River at the easternmost part of the county." (page ii)
Source: US Geological Survey,
Geologic Map of Loudoun County, Virginia
(Geologic Investigations Series Map I–2553)