This is the example of Perdigões. In this image of the early nineties, the olive trees were not yet removed, the ploughing for the vineyards was not yet done and the spectacular areal image that revealed Perdigões set of enclosures was not yet taken. But the ploughing could have been avoided if this picture, available in the net, was carefully studied: part of the two outside ditches are perfectly visible in the south side of the site, near the road.
Of course, Google didn’t exist then and large projects of agriculture were not submitted to impact studies.
Another example is Outeiro Alto. This site is now preserved in an island inside a water reservoir.
But it is interesting to see, in a Google Earth image of 2003 that vegetation defines the “flower” shape of the enclosure. A very thin suggestion of an enclosure (now easier to interpret, after the site has been discovered in the course of the construction of the tank), but a regular practice of analyse this kind of images, especially when the first evidences of prehistoric material are recorded, may be proved worthy.
And could this be a new one found this afternoon? Possibly. We shall see.