The presence of an unusual type of lineation at the base of certain Pliocene phonolite lava flows in the Baringo district, western Kenya, is reported. The occurrence is in the nature of a fluting structure and is quite unrelated to columnar jointing, as it is parallel rather than perpendicular to the surface of the flow. The lavas are not deformed. The most likely explanation is flowage of soft sediment below the weight of the mass of plastic lava moving over it.

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