This paper is the first of a series of reports on the detailed investigations of the Gelogy of Central Vestspitsbergen arising out of the Cambridge Spitsbergen Expedition, 1949. While subsequent publications will consist almost entirely of new data, the purpose of this paper is primarily to compile information obtained previously. Following the Introduction, there is a review of the published literature as it affects the area as a whole; this has been attempted at length to save repetition in the later chapters and in any subsequent papers. The later chapters include a detailed study of the Carboniferous to Lower Permian of Billefjorden, using unpublished material which has been made available from several expeditions of the Scottish Spitsbergen Syndicate, some results from the Cambridge Spitsbergen Expedition, 1938, and from that of 1949 in so far as they affect this particular study. It therefore represents an original contribution resulting from a compilation and checking in the field of the work of a number of geologists.

The palæontological results are being worked out separately, but within the area, exposures are sufficient to provide a reliable correlation of the Carboniferous to Lower Permian succession recorded in a number of vertical sections. We have found that the very variable facies can best be grouped into the following formations, retaining so far as possible the earlier names:

The major Devonian diastrophism was followed by erosion, deposition, and again erosion in the Devonian. Culm of estuarine facies was then deposited in a basin due to subsequent movements along a great north-south Devonian fault-belt. They rest on the Devonian to the west of the fault-belt and on pre-Devonian to the east. After the Culm, local conglomerates reflect movements along this fault-belt at the western margin, and in the centre of the basin evaporites are developed. Although a number of disconformities can be traced, there is no important unconformity in the basin. The widespread transgressions recorded outside this area, equivalent to the base of the Cyathophyllum Limestones and again to that of the Brachiopod Cherts, are marked within the area by distinct change of facies but no angular relationship of the bedding.

The distribution of these various formations is shown in a geological map to a scale of 1:100,000, which is the first comprehensive topographical and geological map of the whole area to be published.

The Creag Strollamus area lies about three miles to the north-west of Broadford, and presents in miniature all the formational and structural elements of the plutonic region of Skye.

The pre-plutonic substructure of the area consists of Torridonian, largely sandstones and grits, overthrust at low angles upon Cambrian limestones. The thrust plane has been thrown into a number of gentle folds on N.E.-S. W. axes, and has suffered displacement by faults of small throw having the same N.E.-S.W. trend. Owing to later erosion the Torridonian sediments remain as a very thin veneer over much of the area, but thicken rapidly towards the north-west.

Tertiary volcanics, very largely basalt lavas, were extruded upon a surface of considerable relief, but have now been partly removed to reveal large stretches of Torridonian. Subsequent movements included the development of a number of N.W.-S.E. or N.N.W.-S.S.E. faults, usually of small throw, as well as a general warping of the area, so that the volcanics are now inclined north-eastwards at angles around 30 degrees.

Particular attention is directed to the disposition of the sub-volcanic surface in relation to the thrust plane. In a south-easterly direction the erosion surface gradually converges on the thrust plane and ultimately, in the area of the Broadford gabbro, descends beneath it.

Gabbros form a number of masses of widely varying size, but evidently represent sheeted bodies, formerly of greater continuity. Gabbro occurs only in localities where, as considerations of structure show, the former presence of volcanics may reasonably be inferred, the sub-volcanic surface representing the downward limit of gabbro just as it limits the volcanics themselves. Within the gabbro masses internal structures can be recognised which agree with those in the basalts.

Petrographically the close relationship between gabbros and basalts is confirmed by the occurrence of grading contacts and the presence within the gabbros of relic textures and small-scale structures, including amygdales, comparable with those of the basalts. It is therefore concluded that the gabbros developed by the transformation of the pre-existing volcanic rocks.

Just as the downward limit of gabbro in the structure of the area is the sub-volcanic surface, so the granites are confined upwards by this surface and downwards by the thrust plane. Granite occurs in place of Torridonian in the pre-plutonic structure. The variation in habit of the granites from “boss-like” to sheeted in a south-easterly direction is to be correlated with this observation.

Having regard to the preservation of pre-granite structures, often of considerable complexity, it does not appear possible that the granites have been emplaced by the mechanical displacement of Torridonian. Transformation of Torridonian, essentially in situ, is therefore considered the more probable explanation. Support for this view is provided by the nature of the junctions between Torridonian and granite. These are invariably merging and show, at least on a limited scale, that granitisation has indeed occurred.

Evidence is given that many of the Mesozoic, geosynclinal serpentines of Turkey are deep-sea lavas, and that they functioned as efficient fertilizers of surface waters leading to rich crops of radiolaria now preserved in cherts and limestones. Furthermore, in anticlinals at Ankara and Alaca Höyük, Palæozoic, Triassic and Jurassic rocks in the condition of a tectonic mélange are overlain unconformably by Upper Cretaceous and Eocene; while, in associated synclinals at Ayas and Kirsehir, crystalline schists and granites, probably Palæozoic or earlier, emerge from beneath unconformable Oligocene. It is suggested that these crystallines are parts of a Pontic nappe which advanced southwards during Upper Cretaceous times, in part overriding and breaking local rocks to yield the Ankara Mélange, in part bulldozing them forwards to form the Taurus Mountains. The displacement along the Anatolian Thrust at the base of the invading Pontic nappe is reckoned at about 350 km.

The Mollusca possess two growth axes associated with the body and the mantle/shell respectively. Evolution of the Lamellibranchia involved assumption by the mantle/shell of responsibility for growth and form; also the formation of anterior and posterior adductors. Change from this dimyarian to a heteromyarian and finally monomyarian condition involved changes in the relations of body and mantle/shell. These are considered with regard to their two major axes in the saggital plane. Although body form may be greatly influenced by changes in that of the mantle/shell, its proportions are only altered where the body is attached by byssus. Then the anterior half may be reduced and the anterior adductor finally lost. This occurs in many Anisomyaria, these monomyarians being divisible into five groups according to habit. Apart from the Limidæ, all are bilaterally asymmetrical. In those which have lost the foot, both axes of the body are effectively lost. Primary pallial attachment is lost but secondary attachment has been achieved in most cases. In the Tridacnidæ (Eulamellibranchia) the mantle/shell has rotated in the saggital plane in relation to the fixed body with resultant loss of the anterior adductor. There is hypertrophy and extension antero-dorsally of the originally posterior siphonal tissues in which zooxanthellæ are contained. Evolution may have proceeded by way of now extinct heteromyarians such as Lithocardium. In the freshwater Acostœa (Mulleria) the anterior adductor is lost during growth following cementation by one or other valve. The form of the body is little affected. Variation and natural selection account for the variety of form and habit exhibited by these diverse monomyarians.

The construction of dams across fresh-water rivers supplying Hydro-Electric schemes has raised the problem of providing less costly methods than mechanical screens for preventing migratory fish from entering inlet and outlet tunnels of water turbines. The paper deals with the possibilities of employing electric screens for such purposes, and gives the results of laboratory investigations followed by site experiments under actual working conditions. Items covered in the fundamental research include (a) a study of trout reactions when subjected to various shapes and strengths of electric fields, and the effects of exposure to them, (b) particulars of electrode arrangements and other factors governing the characteristics of electric fields in waters containing different amounts of impurities, (c) the relative efficiencies in stopping and diverting fish swimming with and against water flows, (d) the conditions necessary for attracting fish to positive electrodes, and (e) some observations on incidental experiments with combinations of lights and electric screens, and with mechanical vibrations. Details are included of the actual screens in operation and the efficiencies obtained from them.

In the latter part of the paper a description is given of an original type of automatic electric fish-counter installed in two Hydro-Electric Station fish-passes in the North of Scotland, for integrating the numbers of ascending salmon and descending kelts through a common orifice.

In Part I brief descriptions are given of the goniatite faunas found at horizons in the Scottish Carboniferous succession; and mainly on the evidence of these faunas, the stages of B, P1; P2, E1; and E2 and A are approximately demarcated. No goniatites suggesting the presence of H, R and G have been seen.

In Part II descriptions are given of certain species of the following genera: Beyrichoceratoides, Anthracoceras, Cravenoceras, Cravenoceratoides, Girtyoceras, Eumorphoceras, Goniatites, Sudeticeras, Dimorphoceras, Neodimorphoceras and a new genus, Cluthoceras.