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:
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Nor image of thine eyes in any spring,—
How then should sound upon Life’s darkening slope
The ground-whirl of the perished leaves of Hope,
The wind of Death’s imperishable wing?”
—Dante Gabriel Rossetti (1828–1882)
“The legislator must be in advance of his age.
Across the mind of the statesman flash ever and anon the brilliant, though partial, intimations of future events.... Something which is more than fore-sight and less than prophetic knowledge marks the statesman a peculiar being among his contemporaries.”
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