MAGNETITE GARNET ROCKS FROM THE MORAINES, 

 CAPE DENISON, ADELIE LAND, 



BY 



ARTHUR L. COULSON, M.Sc., F.G.S. 



(WITH TWO PLATES). 



CONTENTS. 



PAGE. 



I. Introduction 281 



II. Petrography of the Magnetite Garnet Rocks 



1. Mineral Composition 282 



2. Description of Rock Specimens 283 



3. Chemical Characters 292 



4. Summary of Petrographic Characters 293 



III- Position in Grubenmann's Classification of the Crystalline Schists ... 296 



IV. General Discussion 299 



V. A Tourmaline-bearing Magnetite Gneiss 301 



VI. General Summary and Acknowledgments 303 



VII. Description of Plates 305 



I. -INTRODUCTION. 



The rock specimens, which are described below, are part of the collection obtained 

 by the Australasian Antarctic Expedition from the glacial moraines at Cape Denison, 

 Adelie Land. They are schists and gneisses which are chiefly characterised by an 

 abundance of either magnetite or garnet or both. One specimen of epidote-magnetite- 

 schist, No. 989, shows well-developed glacial striae. 



The descriptions are presented in order of relative predominance of magnetite to 

 garnet. In the first two examples, garnet is absent but it forms 40 per cent, of the 

 rocks towards the end of the series. The paper is concluded with the description of an 

 interesting type containing tourmaline, magnetite, and cordierite. 



