130 PEOCEEDINGS OF THE GEOLOGICAL SOCIETY. 



and at Kirkton West quarry. Others are found intercalated among 

 the basalts of Burntisland and Kinghorn. 



(6) Showing abundant rather small olivines, mostly altered into 

 serpentine or calcite, and grains of augite, imbedded in a mesh 

 of slender felspar-crystals, with microlitic augite and minute 

 granules of magnetite. The rocks are often much calcified. This 

 is the common type of the puy-lavas in Central Scotland. It is 

 typically exhibited at Dalmeny and among the Bathgate Hills, 

 Linlithgowshire, and it forms numerous beds in the fine volcanic 

 group seen on the coast of Fife between Burntisland and Kirkcaldy. 



(c) Holocrystalline olivine-dolerite, granular to subophitic in 

 structure, with porphyritic olivines, and lath-shaped felspars 

 partly penetrating the augite : Gallaston, N.W. of Kirkcaldy. 



(d) A characteristic variety containing large porphyritic augites, 

 olivines, and felspars in a partially glassy groundmass which 

 shows felspar-laths, granular augite, and magnetite. The well- 

 known rock of the Lion's Haunch, Arthur Seat, exhibits this 

 structure, but it is probably later than any of the Carboniferous 

 puys. The same structure, however, is found in the crag at the 

 west end of Duddingstone Loch and in the lowest part of the 

 volcanic group of Calton Hill. 



{e) In this variety the porphyritic constituents are augite and 

 olivine, but not felspar, and the base is partially glassy : Craiglock- 

 hart HiU, Edinburgh. 



Additional types will no doubt be detected when the whole series 

 of rocks is fully investigated. 



B. Basalts without Olivine. — Examples of such rocks may be 

 found associated with the more ordinary olivine-bearing varieties. 

 They pass into dolerifces. A gradation may also be observed into 

 the olivine-basalts. Many years ago I traced this passage on the 

 east side of Arthur Seat. The lower portion of the rock forming 

 the Crow Hill ridges is an olivine-dolerite, but as we follow the 

 mass eastward the olivine disappears and the rock exhibits under 

 the microscope a mesh of striped felspars with granular and micro- 

 litic augite. We have here another example of the chemical and 

 mineralogical contrasts which may arise within one mass of igneous 

 material. 



3. In a few districts the puys have emitted streams of Pokphy- 

 EiTE. Eocks of this kind occur in the Limerick basin, having a 

 silica-percentage of more than 60. On the Calton Hill, Edinburgh, 

 and on Arthur Seat certain dull, often strongly porphyritic varieties 



