To back up a theory about the removal of cairns you have to be able to prove that the cairns were there in the first place.

The main theory is that portal tombs derived from the court tombs - many elements of structural design are there. Court tombs were covered by cairns because the roof was corbelled and needed the weight of the cairn material to provide the cantilever mechanism. The move from corbelled roof to capstone was a deliberate one and must have been done for a reason. The capstone allows a monument to be free standing with no need for a cairn.

I will rephrase my 'structurally beautiful' to 'structurally imposing'. Portal tombs are designed to look very powerful. The choices of stone are generally a lot more considered that in long barrows and passage tombs.

The direct move from covered tomb to uncovered tomb does not mean Julian is totally wrong. In fact he would be almost right. The difference would be that they built the portal tombs uncovered (or semi-covered) initially to leave the stones exposed rather than coming a along later and exposing older tombs.

Here's a question ... How the fluck do you cover this?

http://www.megalithomania.com/show/site/406/2124