We found a trail of rubble in the furrow. It started out as dust, then a few larger stones, then bricks, and finally whole chunks of concrete. It looks like a building has been dragged along, breaking apart as it goes. Some of the bigger pieces have metal girders in them.
We started finding the rubble mid-afternoon, and finally made camp next to the largest deposit. The amount of rubble decreases as the furrow continues; the furrow also begins narrowing, as if whatever made it has broken apart. One obvious conclusion is that the rubble made the furrow, in some way I don't understand.
The furrow gets smaller, but it still stretches off into the distance as far as I can see. The other researchers are ignoring the rubble. They don't even want to think about it, or what it might mean. I've chipped off a few pieces and put them in a specimen tube.
No change in the stars tonight, but I've drawn their positions anyway.