Interesting comment of 'collapsed with time'? Technically, a barrow, or tumulus, is an earthen mound raised over a burial by the excavation of a circular quarry ditch encompassing an earth cut burial. Kits Coty, Coldred stones etc. are chambered tombs, erroniously called long barrows in the past. These consist of a stone slab corridor structure with associated burial chambers covered with earth from a series of parallel quarry ditches either side of the chamber. I assume they collapsed with time relates to a chambered tomb?