>> Could the earth-fast builders, with their belief in cromlechs of stone open to the sky, be that
>> later cult Cope theorised about?

The Welsh tombs are undoubtedly related to the Irish portal tombs and the builders were most likely the same people. Including the Welsh and Cornish ones I've been over 150 of these suckers now and I would say that Julian has most likely got it wrong.

So many have no trace at all of any cairn, while others only have a small area around them that it couldn't possibly have covered the whole structure - if they did then the sides of the cairn would have been vertical. Perhaps the sides of some were hidden by the cairn with the capstone being left exposed. One possibilty is that the tombs had a cairn covering and supporting the orthostats and an earth mound covering the tomb and cairn, which could have vanished without trace. If this was the case then I would have thought that at least one would have survived intact and been found by now.

The structural beauty of most also says to me that they were built to be seen.

Several have been found that were entirely covered by peat. None of these have cairns covering them, although they do have a spread of stones like that at Dyffryn Ardudwy.

Chronologically speaking the next group of tomb builders in Ireland were those that built the wedge tombs. These were always covered by a cairn. Often you get a wedge tomb close to a portal tomb, so one possibility is that they robbed the cairn from the protal tomb to cover their new tomb. If they were happy to rob stone from the portal tomb I can't see why they'd leave either the tomb or some of the cairn behind though.

From my understanding they were all meant to be covered with either stone or turf mounds. I agree with your space comments (particularly if you look at Garn Wnda).

The profiles of the tombs (particularly Pentre Ifan) are fantastic - it must have been a shame to cover them.

Cheers

G