Blair Atholl Research Articles

Societies and Academies

Edinburgh Royal Society, November 2 E. B. BAILEY and W. J. McCALLiEN: Perthshire tectonics; Schiehallion to Glen Lyon. E. M. Anderson's stratigraphy has been confirmed, with minor additions. The Dalradian boundary has been shown to be a slide affected by considerable over-folding. This over folding has brought into one and the same district Dalradian with and without a Blair Atholl component. Other slides include the Schiehallion slide, as spectacular as any thrust in the North-West Highlands. Large-scale inversion is a commonplace in the district. Often the older Blair Atholl Series is found downfolded into the younger Perthshire Quartzite Series. The Loch Tay inversion extends fifteen miles across the strike. All the big recumbent folding and refolding is towards the southeast.

The Nasal Bot Fly, Cephenomyia auribarbis Meigen (Diptera, Tachinidae) of the Red Deer, Cervus elaphus L

1. Cephenomyia auribarbis Mg., a tachino-oestrid parasite of the red deer (Cervus elaphus L.), is distributed throughout the deer forests of Scotland. The adult is found on the wing during June and July.2. The larva normally occurs attached to the walls of the nasal passages and pharynx, where it remains for 10 or 11 months. At maturity it drops to the ground and pupates beneath the surface. The adult emerges in 3–4 weeks.3. In January, 1931, a larva of the early third instar was recovered from a stag shot at Blair Atholl, Perthshire. It was found in fat in the pelvic region and not in the nostril or pharynx as might have been expected.4. It is suggested that the larva may have been swallowed by the host and bored its way through the wall of the gut into the peritoneal cavity, whence it had wandered to the pelvic region; or else that a first-stage larva had been accidentally deposited by a female on the hide and had bored through the body wall to the peritoneal cavity.5. The adult female and the early third-stage larva are described and illustrated.6. A comparison is made between the cephalo-pharyngeal apparatus of Cephenomyia auribarbis, Cephalomyia ovis, and Gastrophilus intestinalis. It is noted that the basilar sclerite of the first two species is provided with an accessory lateral appendage on each side. A greater surface is thus furnished for the attachment of the large depressor muscles of the buccal hooks. The larva thus securely holds its ground in the nasal cavities and pharynx, where the risks of summary ejection are always present. In G. intestinalis the accessory appendage is absent. The chances of the larva of this species losing its hold on the gastric mucous membrane of the host are very slight.

XXXIII.—Perthshire Tectonics: Loch Tummel, Blair Atholl, and Glen Shee

The district described is of considerable relief, according to British standards. Pitlochry lies 300 or 400 ft. above sea-level, while two summits, south-west of the River Garry, reach 2559 ft., and Ben y Gloe, north-east of the same, attains to 3671 ft. Exposures are everywhere sufficient for the mapping of groups, but they seldom permit of the following of individual beds or the recognition of the pitch of isoclinal folds.The Geological Survey has mapped the whole district on the six-inch scale, and published Sheets 55, 56, 64, and 65 of the one-inch Map of Scotland—all except Sheet 64 accompanied by explanatory memoirs.

The Scottish Survey Memoirs 1

These three memoirs mark an important change in the publications of the Scottish Geological Survey. The maps are now colour printed instead of being hand-coloured. This is an improvement for which all Scotch geologists will be profoundly grateful. The cost of the hand-coloured maps at their present outrageous prices is prohibitive to most private students. The solid and drift editions of the Blair Atholl sheet, for example, cost 2l. 7s. 6d., and these precious maps may be ruined by a single day's use in the field in wet weather. Moreover, however carefully these hand-coloured maps may be revised they are always liable to suspicion, and occasional errors and omissions are inevitable. The colour-printed maps are in every respect a great improvement.

On a felsite sill near Aberdeen

Larger igneous masses are generally accompanied by minor intrusions in the form of dykes, sills, and sometimes laccoliths. Attention has recently been drawn, in some detail, to numbers of these in recent geological literature dealing with Scotch areas, as in the Survey Memoirs on the Blair Atholl and the Mid-Argyll districts. A characteristic intrusion of this nature which has never been described occurs near Aberdeen, and seems worthy of a brief notice. It crops out on the coast about two miles south of Aberdeen, and is beautifully exposed by the denudation of the coast-line. Although it does not appear on the Survey map (1 in. 77), it forms a continuous wall-like section which can be traced round the cliffs for a distance of about 700 yards. The rock forms a typical sill. It is intruded amongst banded Gneisses, which have a general dark grey aspect, and, as the sill itself is a bright red rock, the contrast is sharp and striking, and produces, indeed, a picturesque bit of coast scenery. As one follows the sill round, it is found, at the southern end of the exposure, to be quite thin, only a foot or two in breadth, and obscured by surface soil and grass. Thence it widens out, and passes, northwards, round a promontory, up the south side of a short gully, enters a cave, and emerges on the north side of the same gully as a fine long vertical wall. Then it rounds another promontory, and runs along both