Reference work entry
These features are small shallow pits formed by rain that falls onto the surface of unconsolidated sand, mud or clay deposits. They are circular or elliptical recesses that remain on the surface of sedimentary rocks. They generally are 2–3 mm in diameter, 1–2 mm deep, commonly form on the top of argillaceous or sandy rock strata, and can also be casted on the bottom face of the overlying strata. They can be used to determine the top and bottom surfaces of a rock (Fig. 3).
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