Notices of Memoirs — The Geological Barvey. 305 



decomposed and is partly replaced by chlorites and iron oxides ; 

 some of the latter mineral is, however, probably original, and 

 appears to be titaniferous. The least altered biotite crystals form 

 irregular wisps between those of the felspar. In this slice but 

 little quartz is visible. There are also a few crystalline grains of 

 a colourless silicate, with low polarization tints, one of which gives 

 straight extinction. Possibly the mineral is zoisite. A second 

 slice shows a lai'ger quantity of quartz in the form of composite 

 gi'ains, probably due to fracture. Felspar and mica are present, 

 as in the last slice, with the addition of a little heematite and one 

 or two zircons. The rock is therefore a quartziferous mica-sj'^enite 

 or possibly diorite. 



The rock obviously resembles the Malvern syenite. The simi- 

 larity between the two has been noticed by Professor Phillips, and 

 later by the Rev. W. S. Symonds ("Records of the Rocks," p. 37). 

 Both these authors regard the rock at Hartley as Malvernian in 

 age ; the former stating emphatically that it is not intrusive, and, 

 in addition, that it differs from all other intrusive rocks in the 

 neighbourhood. This syenite, so far as he could see, did not seem 

 to have produced any alteration on the adjacent I'ocks. 



The underlying quartzite exhibits a somewhat gi-anular and 

 saccharoidal structui'e. One specimen shows slickensides, another 

 a very distinct and well-rounded pebble. On microscopic exami- 

 nation we find that the rock consists almost wholly of rounded 

 grains of quartz, with a few fragments of decomposed felspar. 

 One or two grains show a composite structure, as if derived from 

 a schist. There are also clots of iron -oxide scattered about the 

 slice. With crossed nicols each quartz grain is seen to be 

 surrounded with a thin zone, evidently a secondary deposit. No 

 strain shadows are visible, but dislocations are seen in parts of 

 the field, and near them the grains are slightly crushed. 



A second slice presents a very similar structure, but with a finer 

 texture ; the component grains not being so well rounded as in 

 the last specimen. It shows no distinct signs of crushing, but 

 is traversed by minute veins of quartz which occupy ci'acks. 



The rock is therefore a quartzite wnth well-rounded grains, and 

 is remarkably free from earthy matter. It is identical in every 

 respect with that of the Lickey, and most probably belongs to the 

 same geological age. 



ISrOTIGIBS OIF nVLIBJVCOIIRS- 



The Geological Survey of Great Britain and Ireland. 



[Having, through the kindness of Sir A. Geikie, been favoured 

 with an early copy of the Summary of Progress of the Geological 

 Survey for the j^ast year, and finding it to contain matter of much 

 general intei'est to geologists, we are glad to give it a special notice 

 in our present number. — Editor.] 



DECADE IT. VOL. T. — lAO. YII. 20 



