Bored Stones in Boulder Clays

Abstract

STONES bored by Pholas and Saxicava are by no means rare in the shelly “Basement clay” of East Yorkshire, and I have occasionally found examples in which the shells remained in the borings surrounded by fossiliferous sand, just as described by Mr. T. Mellard Reade from the Lancashire area. These stones are generally limestones of various kinds—Carboniferous, Magnesian, Jurassic, or Cretaceous—and the diversity of their origin seems to show that they have first been scattered over a shallow sea-bottom by floating ice, and afterwards perforated, but I do not think that they can be taken as proof of the marine origin of the boulder clay in which they now lie.