REVIEWS. 



The Study of Progeessive Metamorphism. 



(1) V. M. GoLDSCiniiDT. Die Kaledonische Deformation der 

 SiJD-NoRWEGiscHEN Urgebirgstafel. Vid. Selsk. Skrifter, 

 M.N.KL, No. 19, 1912, p. 11. 



(2) V. M. GoLDSCHMiDT. DiE Kalksilikatgneise und Kalk- 

 silikatglimmerschiefer des Trondhjemgebiets. Vid. 

 Selsk. Skrifter, M.N.KL, No. 10, 1915, p. 1. 



(3) A. Gavelin. Lecture on the Ruotivare Region. Geol. 

 Foren. Stockh. Forh., vol. xxxvii, 1915, p. 23. 



(4) A. Gavelin. Til Fragan om de kristallina seveskif- 

 FRARNAS URSPRUNG ocH METAMORFOS. Geol. Foren. Stockh. 

 Forh., vol. xli, 1919, p. 313. 



(5) P. QuENSEL. De kristalline Sevebergarternas geo- 



LOGISKA OCH PETROGRAFISKA STALLNING INOM KeBNEKAISEOM- 



RADET. Geol. Foren. Stockh. Forh., vol. xli, 1919, p. 19. 



(6) V. M. GoLDSCHMiDT, DiE Injektionsmetamorphose im 

 Stavanger Gebiete. Vid. Selsk. Skrifter, M.N.KL, No. 10, 

 1921, p. 1. 



IT is now almost thirty years since Mr. Earrow first unfolded the 

 evidence for progressive metamorphism on a regional scale in 

 the Pre-Cambrian sediments of the South-east Highlands of 

 Scotland. This early publication has been supplemented by a more 

 detailed map m 1912 in the Proceedwgs of the Geologists' Association. 

 Within the last few years comprehensive studies on progressive 

 metamorphism have been made in Scandinavia, with results in many 

 ways identical with those of Barrow. It is unfortunate, however, 

 that the work of Barrow, preceding as it does by more than twenty 

 years the zonal mapping of Scandinavian areas, has remained 

 unknown to Scandinavian petrologists, and, indeed, as the writer has 

 experienced, to German and Swiss petrologists generally. 



It is to Goldschmidt, Quensel, and Gavelin that we owe important 

 studies in tlie Scandinavian region. 



The argillaceous sediment has been throughout the principal 

 rock type used in the study of progressive metamorphism. 



In the Trondhjem district, Norway, dynamo-thermal zones have 

 been mapped in the Palaeozoic sediments, and the succession, as 

 denoted by the first appearance of indicator minerals, is chlorite, 

 biotite, garnet, the chlorite zone corresponding to Barrow's zone of 

 digested clastic mica. Higher zones undoubtedly exist in this area, 

 but no further subdivision of the garnet zone has yet been published. 

 In the Stavanger district the zones in the Cambro-Ordovician 

 phyllites are chlorite, garnet, biotite, the normal biotite garnet 

 order being here inverted. The reason for this inversion is clearly 

 the composition of the garnet, not a true almandine as analyses 

 show, but one rich in the spessartine molecule. [The same inversion 



