Maybe a little off the subject; but I couldn’t help recalling my years spent in England, first going to school at Cambridge, then marrying and living in Yorkshire, when I came across the interesting phenomenon of “crop marks.” Not the patches of beaten-down crops that idiot hoaxers make in the U.S., to try and convince people that UFO’s made them; but actual patterns, outlines that can be seen from the air over the UK, in their fields. Crop marks are darker patterns, circles, parallel lines, etc., caused by past, ancient inhabitants such as the Romans.
It seems that underneath the vegetation, the soil’s nutritional value has been altered, due to the presence of ancient structures, now buried, hidden beneath the surface. Two long parallel lines, for example, clearly visible from a low-flying plane passing overhead, means that a Roman road (the two ruts necessary for chariot travel; I also encountered these “Roman Roads” above ground while hiking the English countryside) lies beneath the surface. Or dark green, solid circles in the middle of a lighter green field, would mean there are Roman water cisterns underground at that exact spot. Amazing to look down and know that a Roman Chariot actually used the road. What a sense of the past this gives one!
I’m struggling to describe these “crop marks” in my layman’s terms; but I assure you, they are real. Surely you can google (or other search engine) say, “Cropmarks in Britain” and find some interesting literature, even aerial photos of them.. BTW, I visited Hadrian’s Wall, built on order of its namesake Roman commander, to defend against the Scots, in “The Borders,” north UK. There are Roman baths (they were fond of elaborate bathing) there too. Touching the wall and knowing Roman Soldiers marched along it, the so much deeper contact with history available in the UK, is remarkable.