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

CHAPTER XXXVII.

Chapter 4080 wordsPublic domain

ON THE DIFFERENT AGES OF THE METAMORPHIC ROCKS.

Age of each set of metamorphic strata twofold--Test of age by fossils and mineral character not available--Test by superposition ambiguous--Conversion of dense masses of fossiliferous strata into metamorphic rocks--Limestone and shale of Carrara--Metamorphic strata of modern periods in the Alps of Switzerland and Savoy--Why the visible crystalline strata are none of them very modern--Order of succession in metamorphic rocks--Uniformity of mineral character--Why the metamorphic strata are less calcareous than the fossiliferous 481