Notices of Memoirs — Dr. Sicks — the " Grampian Series." 463 



dynamic forces in altering the atomic relationships of the chemical 

 constituents of the rocks, qua the development of new minerals, 

 would appear to have been very limited. 



3. In the present state of our knowledge the two Inost interesting 

 questions presented to us by these rocks would seem to consist 

 (a) in determining to what extent such dynamic deformation, as 

 we actually observe, has been prior or posterior to the ultimate 

 solidification of the various parts of the original magma ; and (b) in 

 determining to what extent simple atomic interactions leading to 

 molecular segregation, supplemented by the action of gravity upon 

 minerals of various densities and by forces of a tidal nature acting 

 upon the magma as a whole, may have caused the vein-structure 

 and the stratiform arrangement, which, whether in its original or 

 in its deformed condition, has constituted one of the most puzzling 

 phenomena presented to the minds of investigators of the Malvern 

 crystallines. 



4. The phenomena presented by these rocks as a whole seem to 

 lend no support to the doctrine of "regional metaraorphism " as 

 usually understood, since, when field-relations are duly considered, 

 it becomes far easier to explain such simulations of "bedding" as 

 are met with, by mechanical deformation of crystalline rocks, to 

 which a diagenetic stratiform structure had been imparted, than by 

 the hypothesis of reconstruction of crystalline minerals out of clastic 

 materials. 



5. The writer, having made free use of the published writings of 

 Phillips, Holl, Riitley, and Callaway, and of the valuable results of 

 microscopic work published by the two gentlemen last named, and 

 having approached the subject in the light of the principles advocated 

 by himself in 1888-9, and since, is happy to find himself to a great 

 extent in accord with Dr. Callaway, though unable to follow him to 

 the full extent in the matter of " dynamic metamorphism." 



Abstracts of Papers Read before the British Association, Edinburgh, 



August, 1892. 



I. — On the " Grampian Series " (Pre-Cambrian Rocks) of the 

 Central Highlands. By Henry Hicks, M.D., F.E.S., Sec, 

 Geol. Soc. 



N his address to the Geologists' Association in the year 1883 

 (Proceedings of the Geologists' Association, vol. viii. p. 270), 

 the author gave the name of " Grampian Series " to a group of rocks 

 which occupy an extensive area in the Central Highlands. He 

 described them briefly as " tender gneisses, bright siliceous schists, 

 chiastolite schists, quartzites and limestones," also some " chloritic 

 schists." He considered them as of pre-Cambrian age, and all the 

 evidence since obtained tends to confirm this view. It is quite 

 possible, of course, that newer rocks may be in places entangled 

 amongst them, and the author pointed out certain lines running from 



I 



