562 Professor T. Groom— The Martky Qiiartzite. 



along the hollow to the N.E. of the exposure described in this 

 paper ; and dark shales of the same lithological character are known 

 to occur below high-water mark on the Anglesey shore at Garth 

 Ferry. The existence of such a band of shale must have been an 

 important element in determining the excavation of the Straits, by 

 whatever agency we suppose them to have been eroded. For, as 

 soon as the retreat of the Carboniferous escarpment began to expose 

 the shales, erosion would be facilitated, and their direction of strike 

 would tend to accentuate, if it did not initiate, the N.E.-S.W. trend 

 of the hollow. 



VIII. — Note on the Hartley Quaktzite. 



By Theodore Groom, M.A., D.Sc, Professor of Natural History at the Royal 

 Agricultural College, Cirencester. 



MY attention has been drawn to a recent notice ^ by Mr. Coles 

 of a quartzite at Martley. Since this area is included within 

 the district of the Malvern and Abberley Hills, which I have been 

 engaged in studying for more than two years, a brief description 

 of the relations of the rocks, as determined by myself in January 

 of the present year, may not be out of place. The small patch of 

 interesting rocks here is likely to become covered up as cultivation 

 progresses ; indeed, the exposure is evidently much less extensive 

 than it was when Phillips described it in his memoir on the Malvern 

 and Abberley Hills. Mr. Coles has, moreover, I think, hardly done 

 justice to the remarkable section exposed here. 



On certain points I am quite in agreement with Mr. Coles. The 

 lowest rock seen is certainly a quartzite of the type found in the 

 Lickey Hills, Wrekin, and, as I hope to show soon, in the Malverns 

 and in Cowleigh Park. 



I could detect no traces of fossils in the Martley rock, though the 

 corresponding quartzite of the Malvern Hills is richly fossiliferous 

 in places. 



The quartzite, somewhat shattered, is arranged in the form of 

 a plicated anticline, or anticlinal dome, dipping towards the west 

 and east, and showing a tendency to a qud-quaversal arrangement. 

 The visible thickness of the quartzite is about 42 inches, although, 

 the base not being seen, a much greater thickness may be present. 



The uppermost rock seen, termed by Mr. Coles a " quartziferous 

 mica-syenite, or possibly a diorite," is indistinguishable from the 

 crushed coarse diorite prevalent in many parts of the Malvern range. 

 The diorite is separated from the quartzite by two feet or more 

 of greenish schists, the " powdery rotten rock " of Mr. Coles. 

 The foliation of the schists is parallel to the surface of the quartzite, 

 and to what is apparently bedding in the latter. These schists 

 essentially resemble certain of those formed by dynamo-meta- 

 morphism in the Malvern Chain, as shown by Dr. Callaway. 



The most remarkable feature in the section is the superposition 

 of the diorite and schists on the quartzite ; the readiest explanation 



1 " An exposure of Quartzite and Syenitic Rock near Martley, "Worcestershire " : 

 Geological Magazine, 1898, p. 304. 



