Overlies

Overlies is the third-person singular present-tense form of the verb overlie. The verb means to lie upon or to be situated above another object, and it is used to describe spatial relationships where one feature rests on top of another. The word derives from the combination of the prefix over- (above) and lie.

In geology and stratigraphy, overlie is a standard term used to describe the vertical relationship between rock units. If Unit A over lies Unit B, then A lies atop B. The unit that over lies is said to overlie the underlying unit. This relationship helps define the sequence of deposition and the relative ages of rocks. Common variants include overlaid and overlain, with overlaid as a past-tense form and overlain as the past participle: “the sandstone overlies the limestone” or “the limestone is overlain by the sandstone.”

The term can also appear in more general usage to indicate that one object or feature is placed on top of another, though in everyday language it is less common than more straightforward phrases like “on top of” or “covers.” In scientific writing, precision about overlying relationships supports interpretations of sedimentary sequences, faulting, and tectonic events.

See also: geology, stratigraphy, sedimentary rocks, lithostratigraphy, superposition.

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