A new barrow built only after the later inhumations? Is that what is meant by "used up"? Am I reading that right?
The sequence was initial inhumations in flat graves followed by cremations in a turf mound then after that barrow was "used up" there were further and later inhumations in one case above earlier (a century )inhumations , but still in a flat grave . This was then covered with a turf mound which then incorporated cremations .
It is not a straightforward linear sequence of burial type but it is for the barrow construction .
Because of the finer detail in dating it shows that variabilty was key ,without it , it would probably have been read as inhumation followed by cremation and the sequential barrow building unrecognised .
So rather than being sequential in the sense of flat graves moving to turf mounds over time as a new burial 'fashion' for want of a better word(!), it was a sequential process from flat grave to barrow within that particular sites own 'life'? with a new sequential process starting from flat grave again after the barrow was, as they've said, "used up"?