Anyway, I have found my first Dartmoor cairn circle and from here I can find the start of my first row. It heads roughly north, consisting of small (a foot or so tall) stones and crosses over a mile of moorland to a terminus on Piles Hill. On its route it passes the sandcastle-esque Butterdon Hill (north) cairn, which has gained its unusual look by excavation followed by a covering of turf. The direction of the row changes slightly north of this cairn, possibly suggesting that it was erected in more than one phase.
As the row starts to head up towards Piles Hill a taller and more modern boundary marker creeps in amongst the lower stones of the row. Further north Sharp Tor and Three Barrows are now in view, more hills topped with bronze age cairns. As the row approaches Hobajons Cross it still consists of very low stones, and the cross itself is merely a taller upright that has been christianised by the incision of a small cross near its top. It is possible that this stone was once the terminus of the row (see Jeremy Butler's "Dartmoor Atlas of Antiquities"). From here most of the stones are missing as the line of the row climbs Piles Hill to its leaning terminal stone (shown as "recumbent" on the OS).
Information about the row from Pastscape, including the possibility that it terminated at Hobajons Cross, rather than the Longstone on Piles Hill.
"( SX 65635880 - SX 65526037) Stone Row (NR) (1)
A stone row extending from a barrow on Butterdon Hill (SX 65 NE 66) to Hobajons Cross (SX 66 SE 58 a standing stone at SX
65516047). The row formerly extended north from Hobajons Cross to the Longstone (a standing stone at SX 65436074) on Piles Hill,
but this stretch was destroyed in 1803 (see SX 66 SE 107).
Also in 1803 stones split by the tare and feather method were introduced into the row, when the alignment was accepted as the boundary between Harford and Langford Lester Moors.(2)(3)
The northern part of the Butterdon stone row has been surveyed from Hangershell Rocks cairn at SX 65645941 to Hobajons Cross
at SX 65506045.
For the 1050m of this part the majority of the several hundred stones are from 0.1m to 0.4m high and form an irregular line. There is a gap of 70.0m on the north side of Hangershell but otherwise the row is fairly continuous. The area is not entirely free of natural surface stones and while some can be immediately discounted occasionally there is a short double or triple row
where all the stones are alike and these which formed the original row cannot now be determined. Barely two dozen stones
are 0.5m high or higher, Hobajons Cross at 1.2m being the highest. It is possible that this was at some stage a terminal stone since it appears to have cup marks on the south face and the extension onwards, to the Longstone, is on an entirely different alignment."
A glance at the map will show you so many stone rows in this area - but the one I mean here is the longest at 1900 metres! It runs north-south along the top of this ridge of moor. Burl quotes it being referred to in a Saxon charter as "the old way with the white stones", and suggests that there must have been over 2000 stones at one time. Blimey.