Figures and plates

(Figure 1) Simplified physiographic map of Arran showing areas covered by the excursion itineraries. Road log localities indicated by numbers. Contour interval 100 metres.

(Figure 2) Simplified geological map of Arran; based on the Geological Survey one-inch map.

(Figure 3) The granite mountains of North Arran. Contour interval 150m. A. The Saddle. 431 m; B. The Archer's Pass, a little over 610m; C. unnamed pass, about 610m; D. A'Chir ridge, about 713m.

(Figure 4) A, Cross section of Dalradian of North Arran from Newton to Corloch. B. Structural model of the Tay Nappe according to Shackleton (1958). Note the position of the slate at the core of the Aberfoyle Anticline corresponding with the Loch Ranza Slate Group in section A. Length of section B is about 30km. C. Major structures in the Clyde Area. Note how the Aberfoyle Anticline has been distorted by the intrusion of the granite (G).

(Figure 5) Index to the geological sketch-maps. (Figure 6), (Figure 7), (Figure 9), (Figure 11), (Figure 13), (Figure 14), (Figure 16).

(Figure 6) Geological sketch-map of the Brodick area to illustrate Excursion 1 and part of Excursion 2.

(Figure 7) Geological sketch-map of the Brodick–Lamlash area to illustrate Excursions 2 and 3. For key see (Figure 5.

(Figure 8) Plan of Dunan Beag Cairn, Lamlash: from The Book of Arran, 1910. p. 76.

(Figure 9) Geological sketch-map of the Corrie area to illustrate Excursions 4 and 5. For key see (Figure 5).

(Figure 10) Diagrammatic cross-section of the rock succession on the Carrie Shore.

(Figure 11) Geological sketch-map of the Glen Sannox and North Glen Sannox area. For key see (Figure 5).

(Figure 12) Plan of the fort at Torr an t-Sean Chaisteil, Sannox; from The Book of Arran, 1910. p. 176.

(Figure 13) Geological sketch-map of the Loch Ranza–Cock of Arran area to illustrate Excursions 8 and 9. For key see (Figure 5).

(Figure 14) Geological sketch-map of the Catacol–Pirnmill area to illustrate Excursions 9 and 10. For key to map, see p. 78.

(Figure 15) Geological sketch-map of the Kingscross—Whiting Bay area to illustrate Excursions 11 and 11a. Note that the Triassic sediments have been left blank. Where indicated the identity of the dykes is as follows: K^C crinanite, K^T tholieiite ^OK^T olivine-tholeiite K^A 'andesitic' quartz-dolerite, F^I pitchstone

(Figure 16) Geological sketch-map of the Largybeg–Kildonan area to illustrate Excursion 12. For key to map see (Figure 5), p. 78. Note that the area occupied by Triassic sediments has been left blank.

(Figure 17) Geological sketch-map of the Drumadoon–Tormore area to illustrate Excursion 13.

(Figure 18) Geological sketch-map of the area around Ard Bheinn in the Central Ring Complex, to illustrate Excursion 14.

Plates

(Plate 1) The Northern Granite Mountains. (For explanation, see page 8)

(Plate 2) Micro-sections of some typical Arran rocks. Fig. 1. Permian sandstone, old quarries at Corrie. x12. Grains of quartz, felspar and quartzite, the surfaces of which have been rounded by wind abrasion ("millet seed" grains), are coated and cemented loosely by limonite. Fig. 2. Lower Carboniferous Sandstone, south side of String Road, 915m SW of Brodick Church. x13. Angular grains of quartz (dusty with fluid inclusions) and of decomposed felspar and siliceous rock are loosely cemented by clay. Fig. 3. Lower Old Red Sandstone, shore cliff, 800m S of Dougrie. x 11.5. Angular and unsorted grains of quartz (clear), decomposed felspar (grey) fragments of mudstone, igneous rocks and oxidized iron ore are compactly cemented by the fine-grained waste of similar material. Fig. 4. Pebbly grit, Dalradian, near SE end of Creag Ghlas Laggen, North Arran. x 10.5. Fig. 5. Cleaved grit, Dalradian, shore 69m ESE of Loch Ranza pier. x9–5. The rock has been sheared. Quartz and quartzite pebbles have been deformed and ground away until their long axes lie parallel to the schistosity which is strongly developed by parallel orientation of the chlorite and muscovite flakes of the matrix. Fig. 6. Slate, Dalradian, old quarries on hillside 2.4km E of head of Loch Ranza. x 13. The paler and darker bands represent more silty and more clayey alternations of the original strata. Within the paler bands the effect of shearing can be seen in the development of a lenticular schistosity on a microscopic scale. Fig. 7. Pitchstone dyke, Schoolhouse, Brodick. x12. Small euhedral crystals of quartz lie in a matrix of rock-glass from which numerous crystallites of pyroxene have grown. In other parts the rock contains euhedral prisms of zoned plagioclase and pyroxene which are not shown in this figure. (Figure 8). Granite, Glen Rosa. x12. The rock is composed of oligoclase (showing straight cleavage lines), orthoclase (turbid), quartz (clear, with tiny inclusions and cracks), and biotite (dark, with straight close cleavage). A small prism of zircon lies on the left side of the topmost biotite). Fig. 9. Olivine basalt lava, Lower Carboniferous, Corrie shore opposite schoolhouse. x10.5. Euhedral phenocrysts of purplish augite (bottom right) and olivine serpentinized along cracks (centre) lie in a matrix composed mainly of plagioclase laths, augite grains, and iron ore granules.

Tables

(Table 1) The geological systems and rock-formations of Arran.

(Table 2) Quaternary geological events and climate phases

(Table 3) major subdivision of the Carboniferous

(Table 4) Faunal zones. Coal Measures.

(Table 5) Major subdivisions of the Permian

References