The mapping of the shafts was all done by radar. At least one of the shafts has been cored, and the soil produced a radiocarbon date of 2500 BC, which matches well with Durrington Walls.
I have no clue what these are and neither, so far as I can tell, does anyone else. Somebody will have to fully excavate a couple of them. Much of the news coverage I have seen assumes that these pits were left open, and that they were all open at the same time. I am skeptical; such a hole in the ground would start to wash in after the first rain, so I am betting they were dug for some ritual purpose and then filled back in. But that's the sort of thing excavation will reveal. It is very easy to tell soil that washed into a hole from soil that was shoveled in, and you can still tell even if the hole was maintained, the soil shoveled out of the bottom as it accumulated. (As with, for example, military entrenchments.) If they had wooden walls, that should also be apparent. And if they were burial pits, that will seriously make some excavator's day.
I also wonder about the layout. The excavators are enthused about the surveying calculations involved in creating this pattern, but the map above shows quite a bit of error. Stonehenge itself is made to a much higher standard of surveying accuracy. Maybe over time the position of the earlier shafts was lost?
This thing is certainly another sign of how willing the Neolithic people of Britain were to put gigantic efforts into moving earth and stone.