@Walter Hinteler,
red the graphics.(Read the paper later). The fluxgate mag can be quite sensitive qnd displayed with the LIDR , I do NOT see any evidence that this is a recent diplay. If it were recent (As suggested from military installations or testing ranges), The "hillshade" output of the LIDAR would coincide with the anomalies quite closely. LIDAR over accentuates any surficiaal feature and Id say that a mound or a series of berms woushow fairly strongly. Unless I missed some of the maps, I dont see tht, In fact, what looks like old field or waterway lineations, suggests that the waterway structurs came much later than the anomalies.
O, my guess is that this stuff really IS quite old.
I wonder if they buried some of the larger doleritic stones , which, by their Fe content would stick out as a positive magnetic anomaly on the fluxgate instrument.
NOW , Id go and do a spinner magnetometre scan. This would quantify and provide age ranges by comparing to each other and to undisturbed sediments.
COOL WALTER.