A manuscript copy, with corrections and editor's notations in red, of the article published in the Philosophical Society of Washington Bulletin, volume 12, 1892

The origin of different kinds of igneous rocks can be understood in terms of their tectonic setting, and by way of the isotope compositions of strontium, neodym

Hess (geological sciences, Brown U.) explores the complex process of the generation and cooling of those rocks formed by solidification from a molten state, eit