150 IGNEOUS GEOLOGY OF THE BATHGATE AND LINLITHGOW HILLS. 



EXPLANATION OF PLATES. 



Plate I. 



1. Coarse-grained dolerite, N. Mams quarry. — Portions of the rock are being replaced by a brownish 

 granular substance, which passes later into analcite. The outlines of the lath-shaped felspars are sometimes, 

 as in the figure, distinguishable within the pseiulomorph. 



•_'. Fine-grained dolerite, Bo'ness. — The rock is practically a holocrystalline aggregate of felspar, augite, 

 olivine, and magnetite. Ophitic structure is not pronounced. 



3. Fetspathic basalt, west of Redhouse. — The porphyritic crystals here are olivines, round which the lath- 

 shaped felspars are arranged in fluxion streams. The small idiomorphic augites are aggregated on the margins 

 of the olivines, and in clumps between the felspars. 



4. Basalt, abore limestone, The Knock. — This rock is srm'ingly porphyritic, with small olivines and 

 augites not very apparent in the figure. The groundmass is an intimate mixture of small felspar rods, 

 idiomorphic augites, and grains of magnetite. 



5. Basalt, Cathlawhill quarry. — Olivine, completely serpentinised, is here the only porphyritic con- 

 stituent. The felspar of the groundmass is reduced in amount, and the crystals are irregularly arranged. 

 The augite is aggregated into heaps and associated with a little glassy base. 



6. Basalt, Kipps Hill. — The phenocrysts are olivine and augite. In the groundmass the felspars are 

 few, the augite more abundant, and the brown, glassy base conspicuous. 



Plate II. 



1 . Ophitic diabase, Kettlestoun quarry. — The augite is cloudy through formation of a brown, granular, 

 isotropic dust. Above the centre is a mass of pyrites, and to the right streaks of the same mineral may be 

 seen piercing a crystal of felspar. 



2. Diabase, Carribber quarry. — The figure shows well the columnar habit which the felspars and augites 

 assume in the centres of the larger sills. The augite is intimately associated with a skeletal growth of 

 ilmenite, and is slightly amphibolised on the margins. The intersertal spaces are filled with micropegmatite. 

 The clear space in the upper right-hand quadrant is an imperfection in the slide. 



3. Diabase, Carribber quarry. — The augite is curved and broken and intergrown with ilmenite. The 

 felspars are much decomposed, and the micropegmatitic matrix is abundant. The clear spaces are wants in 

 the section. 



4. Diabase, Carribber quarry. — The columnar felspars are much decomposed and surrounded by fringes of 

 micropegmatite. The remainder of the intersertal material is made up of coarser intergrowths of quartz 

 and felspar. 



5. Diabase, Carribber quarry. — The figure gives details of the micropegmatitic mesostasis. In places it 

 assumes a linear character and fringes the larger felspars. In others the quartz predominates in the inter- 

 growth, and may appear in ragged growths within the linear material. 



6. Diabase, Carribber Reservoir. — A pseudonioiph of bastite replaces an original crystal of bronzite. This 

 is associated with augite, felspar, ilmenite, and a small amount of intersertal material 



Plate HI. 



1. Diabase, Carribber quarry. — This variety is somewhat finer grained and aphanitic, and encloses a 

 branching augite studded with magnetite grains and rendered almost opaque by decomposition products. 

 Below the augite is a portion of an ocellus with a vacuole. 



2. Diabase aphanite, Kettlestoun quarry. — The aphanite occurs as a marginal modification of the sill. 

 Three vacuoles are shown filled with quartz and calcite. The ragged character of their margins suggests a 

 secondary origin. The edge of the section appears on the left. 



3. Diabase aphanite, Kettlestoun quarry. — The section is imperfect, but shows a portion of an ocellus 

 primarily enclosed in aphanitic material. The ocellus is partially filled with a feathery, felspathic, and augitic 

 growth, and abundant granular pyrites. The central vacuole is occupied by a mass of quartz and calcite. 



I. Scijreijtdion vein, Carribber quarry. — The material of the vein is imperfectly marked off from the 

 aphanite which encloses it. A porous growth of pyrites occurs in the middle of the vein. 



."). Diabase porphyrite, Dyke east of Cockleroy. — Glomeroporphyritic groups and detached crystals of 

 felspar, augite, and olivine occur in a groundmass of minute felspar, augite, and magnetite grains. 



6. Diabase porphyrite, I)ylce east of Bangour Reservoir. — The porphyritic crystals are felspar, augite, and 

 olivine, foreign quartz grains, with resorption borders, are abundant. 



