Phenomenon typical of deserts although until recently it was thought that they only existed in Namibia and Australia. These circular formations, more visible from the air, are formed by creeping desert vegetation around an empty space. Its causes are being investigated and seem to be related to the better use of scarce moisture by desert vegetation. I do not know if they have any relation with the witches of our latitudes, a totally different phenomenon, which I will try to characterize separately.
