For example, structures that cause a significant changes in soil resistivity, but are not characterized by any significant changes such as humidity or storage of nutrients in their surroundings (on the air shots from different periods are not observable either as soilmarks, cropmarks or snowmarks). May be a larger metal objects lying below the level of deep plowing, wood holding moisture.
Kwa mfano, Hiyo kusababisha miundo na mabadiliko makubwa katika udongo Resistivity, lakini si sifa kwa mabadiliko yoyote Muhimu na unyevu au kuhifadhi kavu ya virutubisho katika mazingira yao (juu ya shots hewa kutoka vipindi tofauti si kama imethibitishwa soilmarks Aidha, cropmarks au snowmarks) . Kubwa na inaweza kuwa chuma vitu amelala chini ya kiwango cha kulima kina, kuni unyevu kuikopesha.