Dr. C. Callaway — Metnmoryhic Area in ShropsJiire. 365 



cidence, since, in the contortion of a region, rocks may suffer dis- 

 tortion of strike, and be involved in the dominating movements of 

 another formation. Such facts are familiar to us in the Highlands 

 and elsewhere. 



(2) The gneiss of Primrose Hill is faulted against the Wrekin 

 volcanic group, and towards the dislocation shows progressive signs 

 of great crushing.^ The fault apparently strikes to the north-west, 

 and may very well pass a little to the north of Eushton. 



(3) Some of the rocks of Primrose Hill are very quartzose, and 

 these types, though coarser than the Eushton schist, do not widely 

 differ from it. 



On the other hand, it may be urged : — 



(1) If the Primrose Hill gneiss, which is certainly near a fault, is 

 not crushed into a fine-grained schist, we are hardly justified in 

 applying the crushing hypothesis to the Eushton schist, whose 

 proximity to a fault is not proved. 



(2) While the Eushton schist is uniformly highly quartzose, con- 

 tains hardly any felspar, and is ver}^ fine-grained, the Primrose Hill 

 gneiss is sometimes very felspathic, and is coarsely foliated. 



(3) At Malvern, where the coarse gneiss, the presumed equivalent 

 of the Primrose Hill rock, is frequently traversed by faults, we no- 

 where find, so far as I know, any representative of the Eushton schist. 



On the whole, I incline to the opinion that, in this newly dis- 

 covered mass, we have a fragment of one of the newer gneissic 

 groups. As to its correlation with other systems, we may perhaps 

 saj' that the rock is of Montalban type, without committing ourselves 

 to the conclusion that it is of Montalban age. Comparative litho- 

 logy has become of increasing importance in the study of the old 

 rocks, but at present we require the assistance of stratigraphy. 



It will be seen from the map (p. 363) that the Eushton schist is 

 represented as occupying an area of rather less than one mile in 

 length by about half a mile in breadth. The rock probably extends 

 further to the south, but I could find no exposures in that direction. 



On the west side, the schist can be traced to within about 200 

 yards of a section of volcanic grit of the Wrekin series, in which no 

 strike could be ascertained, but the strike of the volcanic series a 

 little further to the south, in Charlton Hill, is east and west, which 

 is the normal strike of the Wrekin group. As the volcanic rocks 

 dip at a very high angle to the north, it is highly probable that the 

 junction of the two formations is a fault. 



I have been able to find no direct evidence of the superior antiquity 

 of the schist to the Wrekin group. Strange to say, though the 

 Charlton Hill conglomerate occurs within half a mile, and contains 

 many varieties of metamorphic rock, I have failed to detect in it 

 a single fragment which I could safely refer to the Eushton schist. 



In conclusion, I may observe that if this schist is merely crushed 

 Malvernian gneiss, we are furnished with an example of a new and 

 very singular kind of metamorphism, in which the rock which has 



1 The " halleflinta" into which the gneiss gradually passes is prohably, in Prof. 

 Bonney's recent opinion, merely crushed gneiss. 



