The rocks of the New Hebrides belong to at least four groups—two series of limestones and two series of volcanic rocks. The islands are sometimes referred to as if composed only of recent volcanic and coral formations. The existence of a series of old rocks has been believed from the records of gneiss on Espiritu Santo by Levat, and of ores of iron, copper, and nickel. The asserted presence of these materials suggested that the older rocks of New Caledonia form the foundation of the New Hebrides. The existence of the ores and gneiss is, however, discredited by Sir Douglas Mawson (1905, pp. 422, 434–5); he remarked that he had examined “small samples of copper, manganese, and other ores supposed to have been collected in the group” (Mawson, 1905, p. 435). He did not confirm this supposition, though admitting that traces of these metals might occur.

It appears to be still generally supposed that the Ichthyosaurians differed from all modern reptiles in having a short intestine with a spiral valve, like that of the more generalized fishes; and the supposition is rendered all the more plausible by the common belief that some at least of the Labyrinthodonts were similarly characterized. In each case, it is true, coprolites or masses of partially digested food, marked with the line of an intestinal spiral valve, are often found in the same strata as the skeletons; but, so far as I have been able to discover, no instance is known in which the spirally-marked coprolite actually occurs in its natural position in the fossilized animal.

In a previous paper the writer briefly alluded to the evidence, as known from the deep borings in East Kent, afforded by the Palæozoic and Mesozoic rocks, of the operation of a posthumous axis of unrest, probably of Charnian affinity. This conception receives further support from a study of the special characters exhibited by the Wealden of East Kent and the nature of the unconformity between these strata and the Mesozoic and Palæozoic rocks underlying them.