366 SCIENCE PROGRESS. 



Southern Uplands was the detection of radiolarian cherts in 

 the ordovician strata (30), the first of a number of such dis- 

 coveries, which have largely changed our views concerning 

 the conditions of deposit of the strata forming continents, 

 and the relative positions of continents and oceans in past 

 times. 



As an illustration of the light thrown by the zonal 

 method upon the nature of past earth-movements, it is 

 hardly necessary to do more than refer to the elucidation of 

 the structure of the North-west Highlands of Scotland (31), 

 and the detection of a completely new type of geotectonic 

 structure (32). Of a very different nature was the move- 

 ment described by Brogger, which was responsible for the 

 depression of the soft rock in the region which is partially 

 occupied by the Christiania Fjord (33). This work of 

 Brogger's and other discoveries by the same author, to be 

 mentioned presently, are the direct outcome of his detailed 

 zonal work on the thin lower Palaeozoic deposits of the 

 Christiania region (17), a piece of work which is a good 

 instance of the light thrown by modern stratigraphical 

 methods upon questions of denudation, deposition, earth- 

 movement, metamorphism, petrographical complexes, and 

 the distribution of life. 



The effects of pyrometamorphism on rocks of varying 

 character has also been worked out in regions where a 

 detailed subdivision of the rocks has been previously made. 

 Brogger's work in the Christiania region is an example of 

 such work (17), whilst recently Barrow has drawn some 

 remarkable conclusions from the study of a carefully-mapped 

 region around an intrusion of muscovite-biotite gneiss (34). 

 The Bereen district has furnished Reusch with evidence of 

 the effects of dynamic metamorphism on fossiliferous lower 

 Palaeozoic rocks (35), and similar evidence as to the effects 

 of dynamic metamorphism has been collected by Lap- 

 worth (36) and others amongst the disturbed rocks of the 

 Scottish Highlands. 



In palaeontology enough has been recently learned to 

 prove the importance of detailed examination of the fossil- 

 iferous strata, and the value of observations in the field to 



