In the history of aviation archeology is described a number of cases where the landscapes in the growth of vegetation for many years did not show any signs of cropmarks, even other (snow, shadow, soil, humidity).
Katika historia ya archaeologists anga Ikielezewa ni idadi ya kesi ambapo Mandhari katika ukuaji wa mimea ya kwa miaka mingi hawakuwa kuonyesha dalili yoyote ya cropmarks, hata wengine (theluji, kivuli, udongo, unyevu).