Shadow marks are a form of archaeological feature visible from the air. Unlike cropmarks, frost marks and soil marks they require upstanding features to work and are therefore more commonly seen in the context of extant sites rather than previously undiscovered buried ones.
They are caused by the differences in height on the ground produced by archaeological remains. In the case of ancient, eroded earthworks these differences are often small and they are most apparent when viewed from the air, when the sun is low in the sky. This causes long shadows to be cast by the higher features, which are illuminated from one side by the sun, with dark shadows marking hollows and depressions.
Shadow marks are best viewed obliquely rather than from directly above in order to emphasise the effect of the shadows.
Famous quotes containing the words shadow and/or marks:
“Erasmus was the light of his century; others were its strength: he lighted the way; others knew how to walk on it while he himself remained in the shadow as the source of light always does. But he who points the way into a new era is no less worthy of veneration than he who is the first to enter it; those who work invisibly have also accomplished a feat.”
—Stefan Zweig (18811942)
“What is clear is that Christianity directed increased attention to childhood. For the first time in history it seemed important to decide what the moral status of children was. In the midst of this sometimes excessive concern, a new sympathy for children was promoted. Sometimes this meant criticizing adults. . . . So far as parents were put on the defensive in this way, the beginning of the Christian era marks a revolution in the child’s status.”
—C. John Sommerville (20th century)