Unless a series of sedimentary rock layers has been overturned, which layer is usually the oldest? the layer on the top

The correct answer is the layer on the bottom.

Explanation:

The formation of the sedimentary rock takes place by the deposition of sediments at the bottom of the water bodies like seas and oceans. The newer deposits of soil that comes via inland inlets, get settled over the previously deposited sediments. The sediments are brought in spontaneously unless and until they become sufficiently big in order to impart intense pressure on the layers underneath and thus results in the formation of rocks.

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