This abandonment appears to be relatively recent (within the past 15 years). The branch leaves the NS (Southern) main at Calverton, and heads northwest through Casanova to a quarry near the corner of Meetze Rd (Rte 643) and Turkey Run Rd (Rte 779). Casanova Rd, between Calverton and Casanova, parallels the southern end of the line; there were some new ties placed along the tracks for replacement in the near future. The tracks end before they reach the site of the Meetze Road crossing. The abandoned section of the line continued on through the town of Meetze and ended in Warrenton.
Part of the northern end of the line, beginning near the Warrenton Station, has been converted to a trail called the "Warrenton Branch Greenway". It extends over US Routes 15-17-19 on a girder bridge.
The Warrenton station is now a restaurant called "The Depot". There are two cabooses on display, including one painted in N&W red and white, and a position-light signal which was probably moved there from another location.
Thanks to Mike Palmer for contributing information about this route.