Vol. 52.] ON THE KILDARE INLIER. 605 



EXPLANATION OF PLATE XX Fill. 



[The numbers in square brackets indicate spots marked in the maps.] 



Fig. 1. Olivine ?-basalt [8], Grange Hill Kildare. X 35. 



The dark patch is a pseuclomorph of haematite and another red 

 oxide of iron, probably after olivine. The drawing shows also crystals 

 of augite and of altered felspar. The groundmass consists of felspar- 

 needles, small patches of augite and iron ores. 



Fig. 2. Porpbyritic basalt [73], Hill of Allen, x 9. 



The groundmass consists mainly of small felspar-crystals and 

 fresh grains of augite in uearly equal proportions. The porpbyritic 

 constituents consist of very large, much-altered crystals of labradorite, 

 and rounded crystals of augite, two of which are shown in the upper 

 part of the drawing. 



Fig. 3. Augite-andesite [78], Hill of Allen. X 9. 



The drawing shows a large twinned crystal of augite, the central 

 portion of which is intimately intergrown with a pale rhombic 

 pyroxene. The augite encloses also several small patches of magnetite. 

 The character of the groundmass is similar to that of fig. 6. 



Fig. 4. Andesite-tuff [30], Grange Hill, Kildare. X 23. 



The drawing shows angular fragments of two varieties of andesite 

 embedded in a matrix of smaller fragments, broken felspar-crystals, 

 and fine particles. 



Fig. 5. Amygdaloidal augite-andesite [29], Grange Hill, Kildare. X 9. 



The groundmass consists mainly of small felspar-needles, and shows 

 good fluxion-structure. Embedded in it are numerous amygdules of a 

 chloritic mineral and quartz. The larger amygdules, which are more 

 or less circular or oval in section, have a rim of quartz, while the 

 main part is occupied bv the chloritic mineral. 



Fig. 6. Augite-andesite [68], Hill of Allen, x 9. 



The drawing shows numerous small, square-edged felspars, also larger 

 porphyritic felspars, which are greatly altered, but are bordered by 

 a rim of fresh secondary felspar. 



Fig. 3 is the only one in the Plate drawn in polarized light. 



Discussion. 



Mr. W. W. Watts called attention to the presence of olivine and 

 hornblende in the contemporaneous igneous rocks of Kildare. The 

 former mineral was almost unknown, and the latter decidedly rare, 

 in the great Welsh province of this date. 



The President and Mr. Gardixer also spoke. 



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