Probably raises more questions that answers...there seems to be no general consensus on whether chalkland barrows and henge/avenue ditches and banks were kept clear. Would the makeup of the soil surrounding subsequent burials not give a clue as to the composition of the surface of the barrow ?

There are some parallels in present-day funerary behaviour [headstones on graves, family tombs] that suggest that family members would tend the grave after death much in the way we visit the grave, tidy it up and put fresh flowers on it.

I admit to being torn between creating a barrow to be chalk-white so it stands out against the grass, or a turfed-over barrow, thereby sealing the burial or cremation inside.