212 
THE HIGHLAND BORDER ROCKS OF THE ABERFOYLE DISTRICT. 
Fig. 3. Albite diabase, from large intrusion north of Gualann, magnified 25 diameters ; nicols crossed. 
Chief constituent is albite in large rectangular plates and in narrow laths enclosed in titanaugite in ophitic 
fashion. The black crystals are ilmenite. (See p. 195.) 
Fig. 4. Dunite serpentine, Maol Ruadh, magnified 10 diameters. Most of the field is occupied by 
serpentine and carbonates after olivine with characteristic mesh structure. The black crystals are chrome 
spinels. On the extreme right is seen a vein of tufted anthophyllite. (See p. 195.) 
Fig. 5. Ferruginous dolomite, south-west of old limestone quarry, north of Upper Dounans, Aberfoyle, 
magnified 10 diameters. Most of the rock consists of carbonates, with which is associated a little serpentine. 
The black crystals are chrome spinels. Mesh structure is preserved. (See p. 196.) 
Fig. 6. Hornblende schist, opposite Maol Ruadh, magnified 10 diameters. The characteristic lenticular 
distribution of the felspar is shown. The veinlets traversing the schistose structures consist of albite and 
chlorite. (See p. 198.) 
Plate IY. 
Photomicrographs of Rocks. 
Fig. 1. Hornblende schist, opposite Maol Ruadh, magnified 25 diameters ; nicols crossed. The centre 
of the field is occupied by an area of felspar. The equidimensional nature of the albite crystals is in sharp 
contrast with the elongated character of the crystals of hornblende. (See p. 198.) 
Fig. 2. Adinolite schist, Corrie Burn, magnified 10 diameters. The rock consists of a coarsely crystalline 
schistose aggregate of colourless actinolite. (See p. 198.) 
Fig. 3. Garnetiferous epidiorite, Corrie Burn, magnified 10 diameters. The anhedral garnets stand 
out in relief from the surrounding dark minerals (hornblende) and the lighter areas which are occupied 
by felspar and quartz. The narrow veinlet consists of chlorite. (See-p. 198.) 
Fig. 4. Galc-clilorite schist, Corrie Burn, magnified 25 diameters; nicols crossed. Lath-shaped crystals 
of albite, in parallel arrangement, associated with chlorite and carbonates. (See p. 199.) 
Fig. 5. Quartz schist, from exposure by the roadside just beyond the Old Loch Katrine Aqueduct, 
magnified 25 diameters. The lighter bands consist of a granulitic mosaic of quartz with associated pale- 
green micas ; the darker bands are made up largely of iron oxides. (See p. 199.) 
Fig. 6. Chloritic phyllite, from lower slopes of Gualann, near the Corrie Burn, magnified 10 diameters. 
The photograph shows the corrugated folding which is characteristic of the fine sediments associated with 
the hornblende schists. (See p. 200.) 
Plate Y. 
Fig. 1. North-eastern side of old limestone quarry, north of Upper Dounans, Aberfoyle, showing from 
left to right quartz dolerite dyke on the line of a branch of the Highland Fault; serpentine-dolomite 
complex; and conglomerates of Lower Old Red Sandstone age. 
Fig. 2. The Black Shale and Chert Series at the fossil locality on the right bank of the Bofrishlie 
Burn. The almost vertical folding of the beds is well seen. 
Fig. 3. Intensely folded and faulted interlaminated cherts and shales on the prominent ridge north- 
west of Lime Hill. 
Fig. 4. Large included blocks of cherty shale in the basement breccia of the Margie Series at a knoll 
just south of a small stream about 300 yards north-west of the ruins of Bofrishlie Farm. 
Plate YI. 
Geological map of the Aberfoyle district. [Geological lines on the area south of the Highland Boundary 
Fault are taken from the published map (scale one inch to a mile), Sheet 38, of H.M. Geological Survey.] 
