BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 

 Vol. 28, pp. 375-418 June 13, 1917 



METAMOEPHISM AND ITS PHASES ^ 



BY REGINALD A. DALY 



{Presented before tJie Societij December 27, lOlG) 



CONTENTS 



Pase 



Introduction 375 



Definition of metamorplii.sm .376 



Former use of the tei'ui 376 



History of the word "metamorphism" 377 



Discussion of tlie older definitions of metamori>lnsni 387 



Proposed definition of metamorphism 391 



Definition of "metaraorphic rock" 392 



CUissification of metamorphic processes 392 



Requirements of a working classification 392 



Definition of regional metamorphism and local metamorphism 394 



Definition of dynamic metnmorphism 395 



Definition of static metamorphism 397 



Phases of static and dynamic metamorphism 398 



Definition and sanction of "load metamorphism" 400 



Definition of "dynamo-static metamorphism" 406 



Definition of contact metamorphism 406 



Definition and sanction of "load-contact metamorphism". 408 



Proposed ckissification 409 



Attempt at an alternative classification 410 



Favored classification in actual practice 410 



Additional descriptive teims 412 



Ultra-metamorphism 413 



Summary 414 



Referenced 416 



Introductio]^ 



Science is tlie coordiiiation of fact with fact;, fact with j)rinciple, and 

 principle witli principle. It depends on the rigorous use of woixls. 

 Xeither fact nor principle nor coordination can rise into full conscious- 

 ness until phrased in unimpeachal)]e terms. Unceasing attention to the 



Manuscript received by tlie Seoi-etjiry of the Society December 27, 1010. 



(375) 



