bluuebunny/crossref_metadata_2025 huggingface dataset:
The Geological Structure of the Kings-Clere Pericline. The Eocene Succession between Kingsclere and Ecchinswell
Authors: Hawkins Herbert Leader
Published: October 2009

The Vale of Kingsclere is in north Hampshire, about five miles south of Newbury, and just beyond the southern border of Berkshire. Geologically it is a periclinal crest on the anticline that forms the southern limit of the London Basin. It may be considered as the “type-specimen” of a “valley of elevation”, for in 1826 Buckland used it in illustration of the features to which he gave that name; and it, alone of his examples, was mentioned in the somewhat diffuse title of his memoir. There could hardly be a more suitable type selected to represent a pericline, whether considered from a tectonic or geomorphological standpoint.

The floor of the Vale, scoured out by the headwaters of northward flowing streams, is composed for the most part of the Upper Greensand, which occurs as an inlier 4¾ miles long and 1 mile from north to south at its greatest breadth. The southern boundary of the Vale is a steep escarpment of the Chalk, partly breached near the south-west end, and deeply embayed by picturesque coombes at two other points. From the crest of this escarpment, which attains a height of over 850 feet in the west and is only 100 feet lower in the east, a rolling downland is seen sweeping southwards to Winchester and beyond; while to the north the heather-clad commons of the western end of the London Basin form the foreground to a view that comprises Reading, Oxford, the White Horse Downs and glimpses of the Cotswold Hills.
The Interglacial Formation in Viðidal, Northern Iceland
Authors: Lindal Jakob H.
Published: October 2009

The rocks to be described occur within an Icelandic remnant of the North Atlantic Tertiary basalt plateau extending from the Skjálfanda river in the east to Breiðafjord in the west. It is a plateau from 800 to 1100 metres in height, incised by fjords and valleys, and some of the quasi-horizontal surfaces between the valleys may be the but little eroded remnants of the original surface. Two series of Tertiary basalts are recognized, the upper one being in general marked off from the lower in that in the former the rocks are more coarsely crystalline, the flows thicker and often with columnar jointing, whilst veins and amygdales are less common. The sediments found in places between the two series contain fossil plants which are believed to be Lower Eocene in age and to indicate a southern temperate climate. The upper series, designated by Dr. H. Pjeturss the “Grey Stage”, resembles the dolerites of the Palagonite Formation, which latter, however, is much younger. To the south, the plateau descends through the “Heath Plateau”, from 300 to 600 metres in height, to the region of the Palagonite Formation, a thick series of sediments and lavas laid down in the graben of central Iceland. The Palagonite Formation is seen to succeed the southerly dipping basalts of the northern tract, and the view advanced by Pjeturss that this formation is of Quaternary age is now generally accepted.

Between the Vatnsnesfjall (900 metres) on the west and the Viðidaisfjall (1000 metres) on the east is
The geology of the Colwyn Bay district: a study of submarine slumping during the Salopian period
Authors: Jones Owen Thomas
Published: October 2009

The area described in this communication is bounded on the north in part by the coast of Colwyn Bay and farther west by the base of the unconformable Carboniferous rocks. It extends southwards for nearly five miles and westwards to the estuary of the River Conway near Llansantffraid Glan-Gonway. It is included in the area recently described by Professor Boswell (1935).

The town of Colwyn Bay stands at the foot of a steep crescentic scarp which marks an old cliff-line, the base of which is concealed by boulder-clay. The upper edge of the scarp is nearly 500 feet above sea-level, and southward of it extends an undulating plateau culminating on Mynydd Du, 4½ miles to the south, in low twin summits at 1133 and 1139 feet above sea-level. The plateau is traversed by steep-sided valleys eroded by streams which flow northwards towards the bay or westward into the estuary of the River Conway. The watershed between the Conway and the bay drainage pursues a zigzag course in a general north-west and south-east direction across the centre of the area. It runs for long distances through the high ground occupied by the slumped beds described below.

The plateau is mainly upland pasture diversified by rocky knolls and ridges usually covered by gorse and bracken. In some cases the trends of the ridges indicate broadly the general structure of the area, which in others is revealed by long scarps of bare rock, alternating with narrow strips of cultivated ground or pasture. The
The geology of the south-western part of Clun Forest
Authors: Earp John Rowland
Published: October 2009

In my recent paper on the Kerry district (
Q.J.G.S.
xciv, 1938, p. 125) a map of the highly contorted strata in the western part of Clun Forest was published, and the characters and origin of the beds were discussed. Over the southern part of the district which they occupy, however, no account of the related strata was given. The associated beds occupy the area described here, and the description completes the stratigraphical account of the whole region occupied by the contorted beds.

The stratigraphical subdivisions adopted are similar to those in the Kerry district, but, as in the southern part of that district, the Leintwardinensis Shale group cannot be separated. The thickness of strata included between the base of the Wilsonia Grits and the base of the Dayia Beds is here about 3500 feet. This is 500 feet greater than that estimated for the equivalent beds in the Kerry district. The difference may be due to actual thickening, but it is possible that the thickness in the latter district was rather under-estimated. In the Kerry paper, also, it was mentioned that the Platyschisma Beds are never more than 40 feet, and are usually about 25 feet thick. In this district they are even thinner, and seldom exceed 15 feet in thickness.

I. Detailed description of the beds

(a) Ludlovian

(i)
Graptolitic Lower Ludlow Shales
.—Only the upper three or four hundred feet of these have been examined. They are chiefly dark grey, thinly bedded shales, sometimes nodular in character, but seldom
A statistical investigation of the Anthracomyas of the basal Similis-Pulchra Zone in Scotland
Authors: Leitch Duncan
Published: October 2009

In a recent paper on “the Zonal Distribution of the Non-marine Lamellibranchs in the Coal Measures of Scotland” (Weir and Leitch 1936) the lower boundary of the Similis-Pulchra Zone was defined by a fauna that occurs above the Musselband Coal of the Central Coalfield, above the Three-Foot Coal of Douglas and below the Wee (Hurlford Main) Coal of North Ayrshire. The fauna contains a rich and varied assemblage of Anthracomyas which were determined as
A. adamsi
Salter sensu lato. In defining the fauna as that of the base of the Similis-Pulchra Zone, reference was made to the fact that in England and Wales the normal
A. adamsi
is typical of a much higher horizon in the zone (above the Mansfield Marine Band and its equivalents); on the other hand, certain of the associated Carbonicolas (
C. affinis
and
C. turgida
) are typical of horizons that have been interpreted as high in the Modiolaris Zone (Wright's Affinis Subzone).

Referring to the above work, W. B. Wright (1938), from an examination of the illustrations, suggested (a) that the
Anthracomya
is
A. modiolaris
and should not have been referred to
A. adamsi
; (b) that, considering this and the associated Carbonicolas, the fauna closely approximates to that of the base of his Affinis Subzone, defining therefore the upper boundary of the Modiolaris Zone; and (c) that the reference to
A. adamsi
was, in any case, unfortunate, as he did not consider it an exactly defined species and that it was “quite within the range of
The structure of Gower
Authors: George T. Neville
Published: October 2009

I. Introduction

The peninsula of Gower, extending 16 miles westwards between Swansea and Carmarthen bays, is a remnant of the Armorican fold system that at one time formed continuous mountain ranges—the front of Meso-Europe—along the southern borders of Wales. Its coastal outline and trend are a reflection of the earth-movements its rocks have suffered, while its inland topography is also largely determined by the strike of the rock outcrops. Apart from insignificant Triassic outliers in the south-west of the peninsula, the solid geology is wholly Upper Palaeozoic. Coal Measures crop out along its north-eastern border and in the coalfield to the north, but are elsewhere absent. The greater part of the peninsula is a plateau of Carboniferous Limestone, complexly folded, in which synclines of Millstone Grit shales form embayments and depressions at Oystermouth, Oxwich, and Port Eynon, and above which the anticlinal cores are marked by the monadnock hills of Old Red Sandstone—Cefn Bryn and the western downs.

The general geology is illustrated on the maps of the Geological Survey (New Series 1-inch maps nos. 246, 247) and is described in the accompanying memoirs (Strahan and others 1907a, 1907b). Following the early work of de la Beche, the Survey officers clearly distinguished the various rock types, and determined the nature of the major structures so far as this was possible by a close examination of dip and strike, and of lithology. At a later date Dixon and Vaughan (1911, p. 479) indicated the location of some of the zones in
Notes on Cretaceous Asteroidea
Authors: Wright Claud William , Wright E. V.
Published: October 2009

Introduction

The publication by the Palaeontographical Society of a monograph on the Cretaceous asteroids by Sladen and Spencer (1891–1908) and by the Royal Society of a paper by Dr. Spencer (1913) on the evolution of the same group might seem to have exhausted the subject for the time being. Very many of the starfish figured in the monograph, however, came from only one locality and horizon, the Chislehurst Caves and the Coranguinum Zone of the Upper Chalk, and the nature of Dr. Spencer's paper unfortunately prevented the complete figuring and description of many of the species with which he dealt. The rarity even of fragments of fossil starfish compared with the abundance of dissociated ossicles makes it natural that further information should come to light with continued collecting.

It is the purpose of these notes, therefore, to figure and describe starfish of species hitherto known only from loose ossicles, or specimens from zones different from those of previously figured examples, as well as several new species.

I. The Metopaster parkinsoni Series

We have two new species of this series from the high zones of the Chalk.

Metopaster stainforthi
sp. nov. Pl. XIII, figs. 1-4, 11, 12; Pl. XVII, figs. 1,2; Text-fig. 7

Diagnosis
.—Body stellate, of medium height: median superomarginalia fairly tumid, with no definite central area, but ornamented with deep spine-pits, fine round the edge, coarse in the middle: the terminal superomarginalia are broken down into constituent ossicles, which have a definite, though irregular, central area with irregularly scattered spine-pits.
On Northern Glacial Drifts: some peculiarities and their significance
Authors: Carruthers R. G.
Published: October 2009

The President (Prof. H. H. Swinnerton) reminded the Fellows that some time ago Mr. Carruthers had read a paper before the Society “on Northern Glacial Drifts” which provoked much interest; so much so, indeed, that it was decided to devote a separate meeting entirely to the continuation of the discussion after the paper had been published. That discussion was now about to be resumed. He then showed two slides of photographs taken by Mr. R. Bentham of the snout of the Craig Harbour glacier, Ellesmere Land. One of these was taken in June, 1937, and showed water flowing from beneath the glacier while as yet none was flowing on the surface. The second was taken in July, 1937, when the thaw was at its maximum. This showed both surface and subglacial streams in full flood, a condition which lasted three weeks. These pictures gave evidence that subglacial melting did actually take place.

Mr. N. E. Odell said that he was critical of certain expressed views of Mr. Carruthers regarding polar glaciers, and also of one or two other aspects of his important paper. The principal characteristics of high polar glaciers (in contrast largely to glaciers of the temperate zone) were (1) relative freedom from surface moraine; (2) confinement of their morainic load to the lower layers; (3) lamellar movement (that is, differential thrusting within these lower layers); (4) development of imbricate structure within the lower strata; (5) contortion of ice-laminae, especially just above the lower debris-loaded layers and round lenses
The Carboniferous Limestone of the Castleton-Bradwell area, North Derbyshire
Authors: Shirley Jack , Horsfield Ernest Lockwood
Published: October 2009

I. Introduction

The area included in the investigation forms a limestone plateau north of the line Perryfoot-Great Hucklow, generally about 1200–1400 feet above sea-level with broad valleys down to 900 feet and hills up to 1500 feet. The west side is formed by the broad valley running south from Windy Knoll; the northern edge runs along the steep slopes from Treak Cliff, behind Castleton to Bradwell; eastwards the area is confined by the valley running south from Bradwell to Hucklow. On these three sides the limestone is bounded by Edale Shales. On the south the area is bounded naturally by the broad depression in the limestone known as Perrydale. The northern edge of the limestone massif is incised by four narrow gorges: beginning on the west, the Winnats, Cavedale, Pindale, and Bradwell Dale. These display the most important profiles. Between the dales the limestone is exposed on the uplands but good continuous sections are rare, although the large quarries opened between Bradwell and Pindale help considerably in the interpretation of the structure and succession. Mining along the numerous lead veins has also exposed the limestone, but these sections are often disappointing owing to the presence of gangue minerals covering the surface of the veins or joints.

The Castleton area has long been famous for its fossils, especially the brachiopod limestones of Treak Cliff and the Winnats, but, although frequently mentioned, the limestone has never been described in detail. The Geological Survey memoir on North Derbyshire (Green 1887) did not describe
The ammonite body-chamber, with special reference to the buoyancy and mode of Life of the living ammonite
Authors: Trueman Arthur E.
Published: October 2009

I. Introduction

In many works relating to the classification and morphology of ammonites reference has been made to the length of the body-chamber and to the form of the mouth border. There have been numerous attempts to use these features as a basis for the classification of the ammonites and almost equally numerous suggestions that they are practically valueless for this purpose. It is not proposed to give detailed references to this very extensive literature. It may. however, be remarked that, following Suess (1865), Haug in 1898 drew attention to the view that the ammonites could be grouped into those with long and those with short body-chambers and proposed to refer to these as the longidome and brevidome forms. A similar classification was adopted by G. von Arthaber (1911). Doubt as to the value of this basis of classification was expressed by several authorities, including Wedekind (1913, 1916), but the most complete summary of the facts then available regarding the lengths of ammonite body-chambers was published by Diener (1916), who pointed out the variations in the lengths of body-chambers occurring in ammonites which were held to be closely related; Diener also gave particulars of the lengths of body-chamber in a wide range of ammonites of different ages.

It is familiar that the lengths of ammonite body-chambers vary greatly; in some species the length is not more than a half whorl, while in others it is commonly more than a whorl, and in some cases more than one and a half
Loch Awe succession and tectonics: Kilmartin-Tayvallich-Danna
Authors: Allison Archibald
Published: October 2009

I. Introduction

The original of this paper forms part of a Ph.D. thesis accepted by the University of Glasgow, and available for reference in the University Library. With the consent of the author, who went abroad in 1933, the text was recast by Dr. E. B. Bailey for publication, and the illustrations redrawn by Dr. W. J. McCallien. In the meantime, Dr. G. L. Elles in 1935 published a paper dealing further with south Tayvallich, and the island of Danna. Although the present paper was read to the Society by Dr. Bailey in 1936, publication was held over until the author could revisit and re-examine the Tayvallich and Danna exposures in the light of Dr. Elles's conclusions, which had differed materially from those expressed by the author. This was not accomplished until the summer of 1939.

The investigation was originally pursued while the writer held a Carnegie Research Scholarship at Glasgow University.

The rocks of the three areas, exclusive of dykes and superficial deposits, consist of sedimentary and igneous schists of Dalradian age. The sediments are grouped according to E. B. Bailey's classification as follows, in descending order both of age and superposition:—

Of these formational names, three—Ardrishaig, Loch Avich, and Shira—are taken from parts of the Loch Awe district outside the scope of the present paper.

The igneous rocks are grouped under the broad heading epidiorite. Lavas and breccias are strongly developed in the Tayvallich Group, and also in the lower part of the Loch Avich
The geology of Helvellyn and the southern part of Thirlmere
Authors: Hartley John Jerom
Published: October 2009

Since the official examination by the Geological Survey in the seventies of the nineteenth century, more recent work on various portions of the Lake District, carried out by Mr. E. E. Walker, Mr. J. F. N. Green, the late Professor Marr, Dr. G. H. Mitchell, and the present author, has shown that acid rocks are widespread throughout the area and, as foreseen by Sir Archibald Geikie, that their outcrops furnish important facts which any interpretation of the structure of the district, to be convincing, must explain.

The original object of the present communication was to describe the development of this type of rock in the neighbourhood of Helvellyn, an area which, since the time of Clifton Ward and J. J. H. Teall, has received only passing and incidental mention. As the work progressed, however, it was found necessary to extend the investigation and to include the mapping and description of the whole of the Borrowdale Volcanic Series as found in this particular area.

J. C. Ward, who described the Helvellyn range very thoroughly, fully recognized that an unusual type of rock was present in this locality. He discussed it in detail in his memoir (1876, p. 24), but, led astray by his views as to its metamorphic origin, he failed to map it in detail. He made no attempt to separate these flows of acid lava, but included them with other rocks on the one-inch map, indicating them by a symbol representing “mostly altered ash”. This vital omission excludes from
Notes on the glacial phenomena of Arvon
Authors: Greenly Edward
Published: October 2009

The glacial phenomena of Arvon are of very great importance, since it is in this region that the ice of the sea-basin comes into contact with the glaciers of the mountain-land. The country which had been mapped by me at the time of writing this summary just enters the mouths of the great valleys of the Ogwen and the Peris (“Llanberis,” when repeated often, comes to be a little cumbrous) at Bethesda and Bryn-yr-efail. From north-east to south-west it extends from Llanllechid to Carnarvon.

Over most of the platform country, the striae, with the onset-and-lee features, point to the south-west. But at the mouths of the two great mountain valleys they point northwest or north-north-west. Knowing, moreover, as we do (
G. of A.
p. 712 &c and fig. 326) that Anglesey was invaded for some three miles by ice from the mountain-land, we shall not be surprised to find that, at some places in Arvon, the one series is crossed by the other. This transgression is far longer in the case of the Ogwen than in the case of the Peris glacier. In the Peris case, it has not been traced for more than a mile beyond Cwm-y-glo. In the Ogwen case it is found as far north as Llandegai, the northward striae being the later.

Along the foot of the mountain-land, between the Peris and the Ogwen, no great valley opens out, and here, accordingly, no crossings have been found: the south-westerly trend is not interfered with.

Glacial deposits
A statistical investigation of the Anthracomyas of the basal Similis-Puchra Zone in Scotland
Authors: Leitch D.
Published: October 2009

The author's illuminating paper carries a stage further a process that is becoming inevitable in modern palaeontological research: the recognition and description of fossils as groups and not as individuals. There is, however, perhaps some inconsistency in his use o.f mathematical formulae to define his groups, and at the same time to diagnose his ‘species’ and to select a holotype in ~he usual way. It is more than possible that related ‘species’, readily distinguished as separate communities by statistical means, might possess holotypes selected because of their closeness to the respective norms, and yet both falling within the limits of variation of each ‘species’. A holotype then has no intrinsic value: it is merely an incidental illustration of a formula. This is in direct opposition to the strict Linnaean conceptions of such Writers as Bather and Buckman, who held that in the last resort the characters of a species are determined by those of its holotype-conceptions that, as the author so clearly shows, are almost meaningless when applied to the mussels of the Coal Measures. Holotypes are superfluous in statistically defined species, as indeed are named species themselves: communities described by formulae require only formulae for their definition, and the logical nomenclature to be adopted for such groups is more akin to the astronomers' star catalogue than to Linnaean binomials.
The Middle Jurassic rocks of Yorkshire : A petrological and palaeogeographical study
Authors: Smithson Frank
Published: October 2009

I. I
troduction

I
n
Yorkshire the rocks of Middle Jurassic age consist largely of non-marine sandstones and shales usually spoken of as the Estuarine beds. Middle Jurassic times commenced and concluded with marine conditions and there were three marine invasions during the period. In these invasions the sea apparently did not extend over the whole area; hence, although the marine beds divide the Estuarine beds into as many as four divisions, in some places two or three of these divisions merge into one (Table I).

In the present paper the Cornbrash is not dealt with, and the Dogger is referred to only in so far as is necessary for an understanding of the sediments above it. Although the term Middle Jurassic is usually understood to include these beds, I have ventured, for want of a better term, to use it in this paper so as to imply the exclusion of them. Where precision of statement is called for, the contractions shown in Table I will be used.

The Estuarine beds with their marine divisions attain a maximum thickness of nearly 700 feet in the neighbourhood of Ravenscar. Their outcrop on the " solid " map (Geological Survey one-inch map, sheets 33, 34, 35, 42, 43, 44, 52, 53, 54, 63, 72) covers about 380 square miles; but as the outcrop is very irregular in shape, the area over which reasonably safe conclusions as to the conditions of deposition can be drawn is not less than 1500 square miles.

Stratigraphy and palaeogeographical
The buried channel of the Tawe Valley near Ynystawe, Glamorganshire
Authors: Owen Thomas Jones
Published: October 2009

I. I
ntroduction

I
n
1927 several boreholes were put down for the Swansea Corporation by Messrs. Vivians Boring and Exploration Company Ltd. on the floor of the Tawe valley near Ynystawe, nearly six miles above the mouth of the river at Swansea. The boreholes Ynystawe House, on a terrace raised a few feet above the alluvial plain between the site and the river and standing about 40 feet above Ordnance Datum. The boreholes were required to test the bearing capacity of the site for the erection of a large power station.

In all, six boreholes were sunk to varying depths; their positions are shown in Fig. 1. They are numbered in the order in which they were carried out. All except No. 1, which is somewhat to the south of the others, lie nearly on a straight line roughly at right anglés to the valley.

The No. 1 borehole was commenced on 6 April, 1927, and was stopped at a depth of 120 feet, or about 80 feet below O.D. This first borehole revealed the existence of a channel at this locality the floor of which lay at some considerable depth below sea-level at a point six miles above the mouth of the river. The thickness of about 35 feet of gravel and coarse sand was considered ample for the support of the heavy loads of the proposed power station, but the presence of 60 feet of muddy sediments revealed in the lower part of the succession raised doubts regarding the effect of this soft material on the bearing capacity of the site as a whole.
The development of the Towy and Upper Usk drainage pattern
Authors: Neville George T.
Published: October 2009

I. T
he
G
eneral
F
orm of the
T
owy
D
rainage
P
attern

T
he
Towy, like the Teifi, Tawe, and Neath rivers, its sub-parallel neighbours in South Wales, is markedly asymmetrical, and is fed by tributaries most of which flow southwards and enter on the right or north bank. The great majority of the tributaries, and much of the Towy itself above Llandovery, follow courses which are not geologically controlled but which transgress the caledonid structures of the Palaeozoic rocks in a manner characteristically epigenetic : the associated major land surface is a composite plateau also truncating the strata without relation to the structures. Along one or two reaches, however, the tectonic trend has clearly been instrumental in diverting the streams from a rectilinear course (Dewhirst 1930). This has happened, for example, between Bwlch-v-rhiw and Brechfa (O. T. Jones 1912, p. 355; 1924, p. 583; 1930, p. 79), where the Cothi is obviously a longitudinal stream working along the structures and the softer rocks of the Cothi-Rhiwnant anticline (see Drew and Slater 1910, pi. xxix; Davies 1933, pi. xvii). Such tectonic control attains its greatest expression in the Lower Towy valley, which, from Llandovery to Carmarthen, follows almost exactly the core of the complex Towy anticline, and which manifestly owes its present form to relatively rapid erosion along a belt of structural weakness (Fig. 1). Significantly enough, several of the larger tributaries of the north bank, notably the Cothi and the Llandeilo Dulais, enter the Towy opposite deep cols on the south bank, and there is a strong topographical
The glacial phenomena of Arvon, North Wales.
Authors: Greenly Edward
Published: October 2009

Prof. T. N
eville
G
eorge
said that, as in eastern, central, and southern Wales, the sequence of deposits described by the author would imply that there were two major glacial episodes separated by a genial interlude. This is surprising, since the high and extensive mountain mass of Snowdonia might be expected to nourish at least as many successive ice-sheets as the Lake District, and not to remain effectively un-glaciated while the Midland Plain on its eastern flank, and the Irish Sea on its northern, were under an oscillating ice-cover. Moreover, both the Older and the Newer Drift of South Wales are probably referable to the latter part of the Pleistocene, and in that terrain no deposits have been recognized comparable in age with the earlier drifts of the Midlands and East Anglia. A simple stratigraphical correlation would then seem to be suspect, and the speaker asked whether it had been possible to ascertain the respective ages of the two boulder-clays of Arvon. Might not the ancient screes be regarded as an immediately post-Glacial solifluxion deposit, peneeontemporaneous with the esker gravels?

The interpretation of the Ogwen, Peris, and Gwyrfai rivers as primary consequents carries with it the implication that the Deiniol and its continuation in the Seiont are subsequent streams, and the river pattern may be attributed to a secondary structural adaptation by the differential erosion of the Ordovician shales when, with uplift of the Menaian platform, there was a revival of relief and enhanced down-cutting. On this view, the reach of
The CNOC Nan Cuilean Area of the Ben Loyal Igneous Complex
Authors: King Basil Charles
Published: October 2009

I. I
ntroduction

T
he
Ben Loyal Igneous Complex forms an impressive group of mountains situated in northern Sutherland about six miles south of Tongue. The rock types include three distinct varieties of syenites, composing respectively the Ben Loyal range, Cnoc nan Cuilean and Ben Stumanadh, together with related syenites, aplites and pegmatites which constitute numbers of dykes, sheets and veins.

The only previous work on this area of which an account has been published was carried out by the officers of the Geological Survey during the mapping of sheets 108 and 114 (Scotland). In the Geological Survey memoir on Central Sutherland (1931, pp. 174—9), H. H. Read gives a brief description of the field occurrence and petrology of the syenites; the rocks are described as unfoliated syenites and nordmarkites and their general petrographic characters are noted. The evident similarity of the Ben Loyal rocks to those of the Loch Ailsh intrusion is demonstrated both mineralogically and with the aid of chemical analyses. For more general references see J. Phemister (1936, p. 57) and E. B. Bailey and 0. Holtedahl (1938, p. 35).

During the investigation here recorded, a field study was made of the Cnoc nan Cuilean and the Ben Loyal intrusions, and, for purposes of comparison, several traverses were made over the Ben Stumanadh mass.

The primary purpose of this paper is to describe and interpret the petrography of the Cnoc nan Cuilean mass. This intrusion presents features not to be seen in the other two masses, namely, the development
Large-scale superficial structures in the Northampton Ironstone Field
Authors: Hollingworth Sydney Ewart , Taylor James Haward , Kellaway Geoffrey Arthur
Published: October 2009

Detailed mapping reveals many structures, unrelated to the slight regional tilting, folding and faulting, that are determined not by deep-seated movements but by disturbances that are demonstrably of superficial origin. These structures include cambers, gulls, dip-and-fault structure and valley bulges. As a result of these movements dissected Inferior and Great Oolite strata are lowered vertically to the extent of 100 feet or more, so that they swathe the hill tops and valley sides. The causal processes of this camber structure include sub-surface erosion and valleyward outflow of the underlying Lias. Gulls are widened joints in the camber filled with material from above. They usually* trend parallel to the strike of the cambered strata and may attain a width of 40 yards. Step-faulting of similar trend is commonly associated with advanced cambering. The throw of each fault in this " dip-and-fault " structure is compensated for by steep downslope dips (up to 40°) in the inter-fault blocks. Valley bulges comprise a variety of upward displacements of the strata that are confined to the valleys and are due to differential loading of the incompetent Lias. Their origin and mode of development are discussed in relation to the physiography of the area and the fundamental part played by the Lias clay.

The economic significance of the structures in the exploitation of ironstone and in water supply are briefly considered and reference is made to analogous structures in other areas.
Stratigraphy and structures east of Oxford. Part II: The Miltons and Haseleys
Authors: Arkell William Joscelyn
Published: October 2009

The area consists of Kimeridgian, Portlandian, Wealden, Aptian( ?) and Albian rocks (Kimeridge Clay to Gault) with terrace gravels of the River Thame and its tributaries. The Jurassic and Wealden rocks are folded and faulted along northwest axes. After the movements had come to rest the resulting structures were planed off and red sands, attributed to the Upper Aptian or Lower Albian (Lower Greensand), were deposited unconformably. The sands are in turn overlapped by the Gault, which has been traced overstepping unconformably across an eroded anticline in the Jurassic rocks. Finally, the Gault itself is faulted along the same north-west lines as the older rocks, but with downthrows in the opposite sense.
The Miocene beds of Kavirondo, Kenya
Authors: Kent Percy Edward
Published: October 2009

The paper describes the succession in the Miocene beds of localities near the Kavirondo Gulf of Lake Victoria, with particular reference to Rusinga island. Fossiliferous lacustrine beds form the lowest part of a sequence laid down during a phase of yolcanic eruption, and there is an upward passage from clays through tuffs to agglomerates. Plateau lavas were subsequently extruded over the Miocene beds. Conclusive evidence establishes that the beds are Lower Miocene, a fact of importance in relation to the dating of the rich fauna and of the volcanic activity, and in proving the date of deformation of the main Central. African peneplain to be pre-Miocene. The subsequent history is traced, and it is shown that the Miocene beds were successively subjected to dyke intrusion, strong faulting, valley erosion and (in the Lower Pleistocene) to raised beach formation. The disturbance of the Miocene beds includes reversed faulting and is interpreted as due to horizontal compression; it is suggested that it is related to a late Miocene phase of Rift Valley formation.
The compaction of muddy sediments
Authors: Jones Owen Thomas
Published: October 2009

The paper indicates some of the geological consequences of the compaction of muddy sediments under the pressures which are set up in the course of deposition, and supplements the experimental observations recorded by Mr. A. W. Skempton (pp. 119-35 of this volume).
The erratics of the Cambridge Greensand.
Authors: Hawkes L.
Published: October 2009

Fossil Wood from the Cambridge Greensand.
—In discussing the mode of transport of the erratics over the Greensand sea, Dr. Hawkes invoked the aid of drifting vegetation, and especially roots of trees, though he remarked that no tree remains had been reported from the deposit. It may therefore be of interest to place on record, in addition to the fossil resin which Dr. Hawkes mentioned, some instances of petrified wood found in the Cambridge Greensand. Two of these have come to light in the Sedgwick Museum since the reading of the paper, and I am indebted to Dr. Hawkes for drawing my attention to them. One specimen (Sedgwick Museum no. 209), labelled " Cambridge Greensand, Hauxton ", is a piece of phos-phatized secondary wood about 15 cm. in length and up to 5 cm. in diameter; part of it is riddled with
Teredo
-borings. The anatomy, as revealed in thin sections, shows it to be a conifer referable to the form-genus
Cedroxylon
, but some important details, such as the pitting on the walls of tracheids and medullary ray cells, are on the whole rather poorly preserved, so that a complete botanical description and a specific diagnosis are scarcely possible. Interesting features include the rare occurrence of traumatic vertical resin-canals, and the irregularity of the growth-rings. There is no resin-parenchyma, but black cell contents in some of the tracheids are probably resinous in origin; it does not, however, seem likely that a tree of this type would have produced the lumps of amber
The variation in an assemblage of the
Caninia Cornucopiae
plexus from the Middle Viséan>
Authors: Hudson Robert George Spencer
Published: October 2009

A
Caninia cornucopiae
assemblage of C
1
age and one S
2
D
1
are both shown to consist of a dominated and several subsidary forms. The dominant form of the newer assemblage, which is described as
C. lanceolata
sp. nov., shows a definite structural advance on that of the older assemblage, the change being considered to be palin-genetic. Lengthy conocylindrical forms are found in both assemblages; their distribution is discussed and they are considered to be forms successfully adapted to an initially adverse environment by a change in relative growth-rate.
The structure and ore deposits of the Carboniferous Limestone of the Eyam district, Derbyshire
Authors: Shirley Jack , Horsfield Ernest Lockwood
Published: October 2009

The area described consists of Carboniferous Limestone almost surrounded by Edale Shales and an account of the stratigraphy is given. The uppermost group of limestones, belonging to the "reef", is shown to lie unconformably on the normal-bedded D
1
-D
2
limestones. Descriptions are given of the principal exposed sections through the limestones. Structure-contours based on the
Orwnastraea placenta
horizon high in the D
2
limestones demonstrate the tectonic movements of the mid-Carboniferous. The distribution of the main lead-ore veins is shown to be nearly related to the structures of the limestones.
Large-scale superficial structures in the Northampton Ironstone Field
Authors: Hollingworth S. E. , Taylor J. H. , Kellaway G. A.
Published: October 2009

From Major J. C. McM
ath
, B.Sc. F.G.S. :—

The authors are to be congratulated on these detailed researches and conclusions, with their interesting economic implications. The work emphasizes afresh the great caution necessary in the interpretation of tectonics generally and it is clear that a revision of much structural and stratigraphical work is required in the light of the authors' results. It can be expected that wherever strata of strongly contrasting competency under load occur analogous phenomena may be found.

Features similar to those described in the paper, though on a much smaller scale, have been observed by me in the lateritic areas of Lake Province, Tanganyika Territory, particularly in the Saragura and Mawe Meru areas to the south-west of Lake Victoria.

“Dip-and-fault” structure, together with cambering, were noted especially on the lateritic flats abutting on the Rhino and Mabubi rivers. The features were developed a short distance from, and parallel to, the courses of these streams, and they faded out where the laterite was of little thickness or where it directly overlay the igneous country rock. The structures were best seen where the laterite was over eighteen inches in thickness and was underlain by ferruginous earth or clay (uncemented decomposition products of the country rock). Both “dip-and-fault” structure and cambering could also be seen on a very minor scale in old prospecting trenches where these were of some size. No “valley bulging” was observed.

Authors' reply :—

The authors write that they recognize that, as observations accumulate from a
Intraformational Contorted Rocks in the Upper Carboniferous of the Southern Pennines
Authors: Cope Fred Wolverson
Published: October 2009

Beds of contorted shale, both overlain and underlain by normally bedded shale, occur in the Millstone Grit and Lower Coal Measures of the Goyt Trough to the west of Buxton. A brief synopsis of the geology of this area is given. The beds of contorted shale, usually from 6 inches to 2 feet 6 inches in thickness, are remarkably constant in horizon throughout the area; the majority directly overlie marine bands, but at least two are unassociated with these fosailiferous shales. Structures discernible within the contorted beds comprise sheer-planes and small folds. On each limb of the Goyt Syncline both the axial planes of the small folds, and the shear-planes, clip towards the major axis at an angle greater than the stratal dip. Wherever the pitch of the small folds can be observed it is northerly, in the same direction as the pitch of the major fold. Contacts of the contorted beds are almost invariably plane surfaces, often polished or bearing slickensides running along the line of dip.

The contorted shsles are considered to be of tectonic origin and to be an expression of adjustment through bedding-plane slip during the folding of a succession of rocks of varying competency. It is thought that shearing, resulting from bedding-plane slip, affected the least competent beds in the succession.

Shear-planes are interpreted as fracture cleavage and the small folds as congruous drag-folds.

Similar beds of contorted shale occur at some of the same horizona on the borders of the North Staffordshire Coalfield and in Lancashire.
The Relation of the Main Peneplain of Central Africa to Sediments of Lower Miocene Age
Authors: Dixey Frank
Published: October 2009

Observers of the Lower Miocene beds of kavirondo Gulf, kenya, and of the western side of Lake Rudolf, Have come to the conclusion that these beds have been faulted below the level of the adjacent main peneplain, usually referred to as the “Miocene” peneplain, and that the age of this peneplain must therefore be pre-Lower Miocene. In this paper different interpretation is advanced, namely; that the peneplain was eroded across the sediments as they now stand, and that these have been revealed by the erosion of the Pliocene cycle at a lower level; the date of termination of the main peneplain would thus fall within the later Miocene, assuming the whole of the Pliocene was required for the erosion of the Pliocene cycle. This view is based on a brief survey of the geomorphology of the region, with special reference to the erosion surfaces and the limiting escarpments, certain of which are regarded as essentially erosion surfaces and the limiting escarpments, certain of which are regarded as essentially erosion-scarps and not as fault-scarps postdating the main peneplain. In East Africa there are remnants of a number of erosion surfaces at various levels, hidden to a greater or less extent beneath a cover of volcanic rocks, and it is suggested that failure to recognize the significance of the “pre-Rift” topography has sometimes led to misconceptions of the extent and nature of the rifting.
The Harlech Dome, north of the Barmouth Estuary
Authors: Matley Charles Alfred , Wilson Theodore Stacey
Published: October 2009

The area described, 150 square miles in extent, lies between the Barmouth estuary and the Vale of Ffestiniog and contains some 10,000 feet of Cambrian rocks which range from ?Lower Cambrian to Ffestiniog Flags and include thick formations of grit. The igneous rocks are all intrusive, are of Lower Palaeozoic age (though of more than one date), and are nearly always found in an altered condition; they are " greenstones " of either dioritic or basic composition. Quartz veins and metalliferous lodes are common. The sediments, the materials of which are chiefly derived from an easterly extension of the Mona Complex of Anglesey and south-western Caernarvonshire, have undergone low-grade metamorphism; some beds (especially the Manganese Ore Bed) are rich in authigenic spessartite.

The general structure is a broken anticlinorium which has been compressed from west to east. The cleavage is predominantly northerly. Faults are numerous, the latest being an important north-and-south series with displacements up to about 4000 feet.
The Great Glen Fault
Authors: Kennedy William Quarrier
Published: October 2009

The powerful dislocation which intersects Scotland along the line of the Great Glen has, in the past, been regarded by most geologists as a normal or dip-slip fault with a predominant vertical downthrow to the south-east. A reconsideration of the entire problem now suggests that this view is no longer tenable and that the dislocation is, in reality, a lateral-slip or wrench fault with a horizontal displacement of approximately 65 miles. Such an interpretation is supported by several independent lines of evidence, as follows :—

(1) The dislocation possesses physical characters unlike those of most normal faults but similar to the great strike-slip shears of the California Coast Range.

(2) It belongs to the same system as the Strathconon, Ericht-Laidon and Loch Tay faults, all of which have proved lateral displacements of up to 5 miles.

(3) It displaces the great belt of regional injection which affects the Moine Schists of the northern and Grampian Highlands, the nature and amount of the displacement being consistent with lateral shift but not with vertical downthrow.

(4) It similarly displaces the metamorphic zones of the Highlands in an equally significant manner.

(5) It truncates the Strontian Granite, the southern portion of which, according to the detailed structural evidence, is missing. The missing portion, moreover, can be identified in the Foyers mass which outcrops on the other side of the fault-line some 65 miles to the north-east and is similarly truncated by the fault. These two major Caledonian intrusions consist of identical rock types and are structurally homologous.

(6) Finally, the occurrence of Lewisian and Torridonian rocks in Islay and Colonsay and the presence of the Moine Thrust-plane in the former island are more readily explained on the assumption of a lateral rather than a vertical displacement along the fault.

Although the dislocation is still active, the available evidence indicates that the main lateral movement was accomplished prior to the deposition of the Upper Carboniferous sediments of Lochaline and subsequent to the intrusion of the Strontian and Foyers (Lower Old Red Sandstone) granites. Middle Old Red Sandstone strata along the Great Glen have, moreover, suffered intense crushing and deformation during the faulting, which must, therefore, be referred partly if not wholly to a post-Middle Old Red Sandstone epoch. The sinistral nature of the displacement, i.e. towards the south-west on the northwest side of the fracture and towards the north-east on its south-east side, implies the operation of a stress system involving regional compression acting in a general north-and-south direction accompanied by an east-and-west relief of pressure. This is regarded as evidence of the fact that the Hercynian forces, to which the formation of the Great Glen Fault is ascribed, were already in operation during Upper Old Red Sandstone or Lower Carboniferous times.
The complex intrusion of Welfield, near Builth Wells, Radnorshire
Authors: Jones Owen Thomas , Pugh William John
Published: October 2009

The paper deals with an area of dolerites intrusive into Llandeilo Shales and forming a prominent ridge near Welfield, north-west of Builth. The area has been mapped on the scale of 25 inches to the mile and an analysis of the relations between the dolerites and the associated strata, usually strongly baked near the contacts, leads to the conclusion that the ridge is occupied by a core of dolerite having the habit of an elongated .laccolith. The inferred main body is accompanied by many lenticles of dolerite on the flanks of the structure and also sheets which appear to spring off from two dyke feeders near the crest of the laccolith.

The whole area has been tilted to the north-west in post-Silurian times. The height of the laccolith is inferred to have been about 500 feet and its width about 1500 feet, and it was intruded under a cover of Ordovician and possibly early Llandovery sediments estimated to be at least 4500 feet thick.