Joining the Shenandoah Valley to the Piedmont region of the state, it is the site of the mountain crossing of Interstate 64, U.S. Route 250, and the former Blue Ridge Railroad which later became part of the Chesapeake and Ohio Railway and is currently part of the CSX line. With an elevation of about 1,900 feet (580 m), it is one of the lowest gaps between Manassas Gap and the James River. Rockfish Gap lies along a drainage divide between southeast-flowing streams that drain to the James River and northwest-flowing streams in the Shenandoah River system.
Rockfish Gap is underlain by greenstones of the Catoctin Formation, a late Neoproterozoic geologic unit exposed throughout the Blue Ridge Mountains in Virginia, Maryland, and southern Pennsylvania. Catoctin greenstones were originally erupted as basaltic lava flows 550 to 565 million years ago and later metamorphosed and deformed during the late Paleozoic Alleghenian orogeny (300 to 330 million years ago).[2] Rockfish Gap lies astride a north-northwest trending fracture zone; some fractures are intruded by diabase dikes of Jurassic age. The broken bedrock along this fracture zone is more easily eroded than unfractured bedrock - likely the reason for the formation of the gap at this location.[3]
History
In the 18th century, early trails used by Native Americans were gradually expanded to accommodate the westward expansion of Virginia colonists. The Three Chopt or Three Notch'd Road had been established in the Colony of Virginia between Richmond and the Shenandoah Valley by the 1740s.[4] Most likely, the road followed an ancient Monacan trail from the village of Orapax (east of Richmond) to the western Shenandoah Valley.[5] This well-planned route required only one major river crossing, the Rivanna at Charlottesville, with inns or taverns spaced about 10 miles apart. By 1782, carriages could cross the Blue Ridge at Rockfish Gap.
In the early 20th century, a road which was designated U.S. Route 250 in 1935 was built across the gap. In 1972 and 1973, sections of the new Interstate 64 were completed across Afton Mountain at Rockfish Gap.[7][8]
Fog, hazardous driving conditions
Rockfish Gap has been the site of several large multiple vehicle collisions on Interstate 64 during fog conditions on Afton Mountain, which peaks at about 1,915 feet above sea level. In April 1992, there were 2 fatalities in a 60-car pileup. In late April 1998, another wreck involving 65 cars sent 40 people to area hospitals. Less than three weeks later, there was another 18-car crash. Fog was a factor in all three incidents.[9]
Motorists approaching from lower elevations sometimes suddenly encounter a dense fog as they approach the summit of the gap. A lighting system within the pavement to help designate lanes automatically activated by fog sensors was installed by the Virginia Department of Transportation (VDOT) to improve safety during such weather conditions.
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