ECLOGITES IN CALIFORNIA/ 



CONTENTS. 



European Eclogites. 

 California Eclogites. 



San Martin. 



Calaveras Valley. 



Tiburon. 



San Jose. 

 Oregon Eclogites. 

 Conclusion. 



The term "eclogite" was first introduced into the geological 

 literature of Europe in 1822 by Haiiy in his Traite de miner alogie, in 

 which he gave the name to a rock composed chiefly of green augite 

 and garnets. In the present paper the name is applied to a rock 

 derived from some eruptive and bearing garnets in a matrix composed 

 essentially of some form of augite, or of hornblende, or of both augite 

 and hornblende. The various secondary minerals are given in the 

 descriptions that follow. The term eclogite has proved useful, and 

 the rock has evidently been an interesting one to European petrogra- 

 phers, for as far back as 1884 Lohmann^ gives two pages of bibliog- 

 raphy as an introduction to his paper on eclogites. Since then many 

 articles have appeared in English and continental journals, the most 

 recent being the excellent paper by Hezner,-' which gives a discussion 

 of the petrographical relations of eclogites and amphibolites found 

 in the Tyrol Alps, with a bibliography of over seventy references. 

 Hezner's article was received after the present paper was written, 

 and although some few extracts from it have been inserted, the 

 special student of these rocks is referred to the original article for the 

 full details of this important contribution to the subject. 



1 The writer is under obligations to Dr. J. P. Smith, of Stanford University, for 

 suggestions and advice. 



2 "Neue Beitrage zur Kenntniss des Eklogits voni mikroskopischen, mineralo- 

 gischen und archaologischen Standpunkt," Neues Jahrbuch filr Mineralogie, Geologic 

 und Paleontologie, Vol. I (1884). 



3 "Ein Beitrag zur Kenntnis der Eklogite und Amphibolite," Tschermak. 

 Mineralogisch-petrographische Mitteilungen, Vol. XXII (1903). 



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