A menhir, to save anyone the trouble of accessing yet another site, is nothing more than a standing stone. The Merrivale example has been measured at around 3.2 metres or around ten and a half feet. Above the ground. How much is below the ground must remain conjecture, but it has to be a fair amount given the weight it has to support. The stone stands here, south of Merrivale's celebrated double stone row which, when you get close, is not as dramatic as it sounds and enjoys the indignity of being bisected down the middle by a nineteenth century leat.
In the dips between tors, in those places without the necessary gradients to enable the downward flow, and where the granite forms a basin, the water forms into stagnant, muddy pools that turn the sediment black and which suck in the occasional boot. For some reason that is most likely not remotely ethereal let alone magical, stone rows are often associated with these black pools. Mostly they lie to one side or the other and any solemn walk along the row involves regular diversions from one side to the other.
One explanation of rows and circles is to do with the creation of electrical energy by the organised weaving of people between the stones. Something like a may pole dance. Participants, joined at the hand, weave between the stones at such a pace that their latent electricity conspires with the stones to produce something greater. Something akin to a magnetic motor perhaps. Something sufficient to enable ... what exactly. To power up a ley line?
The trouble is, what they did or didn't know three thousand or more years ago is, when viewed from this day and age, always informed and always betrayed by what we think we know now. The Beaker People didn't read Arthur Watkins. The Merrivale Menhir might work just as well as a meeting point as it does a teller of the seasons. In its favour, for those more interested in the second possibility, is that it brings with it a fine view of the horizon west of Dartmoor and there's also the possibility that it once had a standing partner that might well have given an indication of alignment.
Or neither of the above. Past a very obvious and verifiable measurement on a notable day - and taking into account any shifts in the planetary tilt - there's no evidence to speak of that can inform the modern, inquisitive mind, about what exactly the ancient people of Dartmoor had in mind when they went to the effort of dragging huge pieces of granite into position and setting them into the ground.
And in turn, that informs what the modern mind wants to achieve from their existence. For in having little or no serious evidence, the observer is free to make his or her own associations. Or, on a simple level, just be satisfied at the spectacle, perhaps become involved in the textures of hacked rock or notice the juxtaposition of stone and moor. And to note that despite all that the Goddess can do to reclaim what was hers, Dartmoor is, nevertheless, an imposed landscape that would, over the decades, revert back to a broadleaf forest amongst which any natural or unnatural alignment would be lost. Where sunrise and sunsets would be no more than splintered, refracted light glistening amongst the greenery. And where buried stones would, slowly and surely, be laid aside by the irrepresible root systems of oak and ash and beech.
For those sad enough to care, the dark splodge to the right of the stones is a camera artifact that I haven't been able to dislodge and for which I'm too lazy to paste out. And for any avid topographers, this looks past the end of the southern Merrivale Row off towards the radio mast on North Hessary Tor with part of King's Tor on the right.