A Manual of Elementary Geology or, The Ancient Changes of the Earth and its Inhabitants as Illustrated by Geological Monuments

CHAPTER XXX.

Chapter 3368 wordsPublic domain

ON THE DIFFERENT AGES OF THE VOLCANIC ROCKS.

Tests of relative age of volcanic rocks--Test by superposition and intrusion--Dike of Quarrington Hill, Durham--Test by alteration of rocks in contact--Test by organic remains--Test of age by mineral character--Test by included fragments--Volcanic rocks of the Post-Pliocene period--Basalt of Bay of Trezza in Sicily--Post-Pliocene volcanic rocks near Naples--Dikes of Somma--Igneous formations of the Newer Pliocene period--Val di Noto in Sicily 397