Vol. 51.] PEOF. T. G. BONNEY ON THE NAEBOBOUGH D1STE1CT. 27 



elongated form of the felspar in its groundmass suggests that this 

 constituent is mainly plagioclase. 



The quarry west of Narborough, near the Huncote road, has 

 been much enlarged and deepened. 1 The stone which is now 

 being raised appeared to me slightly coarser in grain and more por- 

 phyritic than it was at our last visit, so I have examined micro- 

 scopically three more specimens ; one, as an average sample; another, 

 containing a dull green mineral in rather narrow prisms, about | inch 

 long : and a third which includes a darker node or fragment about 

 1 inch in diameter. They are very slightly coarser than the 

 specimen already described, and quartz occurs as a porphyritic con- 

 stituent as well as felspar, but in smaller grains, approximatively 

 four times the diameter of those in the groundmass. The ferro- 

 magnesian constituent is ill-preserved ; probably, as in the other 

 slides, some biotite has been present as well as hornblende. But 

 even the larger green crystals already mentioned consist of a mass 

 of secondary products among many granules of iron oxide. Their 

 shape, however, corresponds better with that of hornblende, and the 

 mode of occurrence of the black grains suggests that, as is common 

 in andesites and trachytes, they were separated from the original 

 mineral at a stage in its history anterior to the final consolidation 

 of the rock. The enclosure consists of lath-like felspar (decomposed) 

 with a little interstitial quartz, rather more iron oxide (some being 

 haematite) than in the surrounding rock, and about the same amount 

 of the ferromagnesian constituent. This rock, which perhaps is an 

 included fragment, on the whole resembles that of Barrow Hiil 

 more than any other in the neighbourhood. 



About a furlong from the road to Huncote, and rather less than 

 ^ mile from the last-named pit, a new one was opened in September 

 1893. This is in a field on the right bank of a small stream. The 

 excavation already has attained to a considerable size, and trial- 

 openings have shown that the ' syenite' is within a short distance 

 of the surface over an area perhaps half an acre in extent. The 

 rock on the western side of the pit is covered by about 1 foot of 

 soil, and I was told that in one place it had come still nearer the 

 surface. It lay at a depth of about 5 feet on the north and 11 on 

 the west, but towards the east it appeared to be shelving down more 

 rapidly. In all these places it was overlain by Keuper Marl, and 

 no true Boulder Clay was visible. The soil, at the time of my visit, 

 had been stripped away, exposing a surface of the rock approaching 

 100 square yards in area. This was rather irregular, without any 

 signs of glaciatioii, and not very much decomposed, the rock, within 

 a few inches of the top, being in fairly good condition. Macro- 

 scopically it seemed a shade coarser than that of the pit nearer 

 Narborough, but, after examining a section under the microscope, I 

 am unable to discover any noteworthy difference between it and the 

 specimens described in the preceding paragraph. 



1 To a depth of 60 or 70 feet from the surface, or about 50 feet into the 

 ' syenite.' 



