bluuebunny/crossref_metadata_2025 huggingface dataset:
Mesonacidæ of Comley in Shropshire, with a discussion of Classification within the Family
Authors: Raw Frank
Published: October 2009

The trilobite family Mesonacidae was erected by Walcott (1890
b
) in his “Fauna of the Lower Cambrian or Olenellus Zone” for the genera
Olenellus, Mesonacis
, and their relatives, which especially characterize that rock series.

The first discovery of a Mesonacid in Britain was made by C. Lapworth at Comley in Shropshire; and was recorded in 1888 in the
Geological Magazine
and in
Nature
, the species being named
Olenellus callavei
.

In 1890 a short characterization of this species by him appeared in Walcott's above-mentioned monograph (p. 640), and Lapworth himself in 1891 described and figured the species under the name
Olenellus
(
Holmia
)
callavei
.

In 1910 appeared Walcott's monograph on “Olenellus and other genera of the Mesonacidæ”. In this, Lapworth's species was illustrated and was referred to Matthew's genus
Callavia
, to which also was referred a new species from Comley, the characteristics of which were furnished by Raw, described below (p. 274) under
Nevadia
(Walcott, 1910, pp. 282–3, pl. 42, figs. 1–4). In this monograph were brought under review all the known examples of the family, many of them discovered and described by Walcott himself; and to it as well as to his previous and later papers all students of the family are indebted.

Earlier than this Dr. E. S. Cobbold had commenced his intensive study of the Cambrian rocks and fauna of Shropshire, furnished not only in natural exposures and in quarries, but also by about sixty special excavations made by him, about half of which exposed Lower Cambrian rocks. In a
New Lamprophyres and Monchiquites from Jersey
Authors: Smith Herbert Gladstone
Published: October 2009

I. Introduction

That mica-lamprophyres exhibit certain abnormalities has been recognized by most petrologists. According to Sir Jethro Teall (1888, p. 350), they do not fall readily into any scheme of classification; a similar difficulty is felt by Dr. A. Harker (1909, p. 150), while Dr. N. L. Bowen (1928b, p. 259) considers it necessary to advance a theory involving special conditions of intrusion for these rocks.

On previous occasions I have made attempts to collect information with the object of throwing some light on the subject, but the resulting tentative suggestions did not bring a solution of the problem much nearer. It was, therefore, with much pleasure that I learned from Dr. A. E. Mourant that he had, in the course of his survey of the island of Jersey, found several unrecorded lamprophyres. An invitation from him resulted in a visit to the island in the summer of 1934, and this paper sets forth some of the results then obtained. An earlier paper dealt with the known lamprophyres of Jersey (Smith, 1933), the work being based on that of C. Noury and Dr. G. H. Plymen. In the present communication only the “new” lamprophyres are described; they are nearly all exposed along the coast, and are dealt with in the order in which they are met, commencing in the south-west and travelling clockwise round the island.

The several dykes of lamprophyre penetrate all the major formations of the island, including all the conspicuous masses of granite, and there can, therefore
Some British Trilobites of the Family Calymenidæ
Authors: Shirley Jack
Published: October 2009

I. Introduction

The study of the Calymenidæ was begun with the re-examination of the figured specimens and described types of the British species, and the results of this work have already been published (Shirley, 1931, 1933). An extensive series of British and foreign specimens has been examined. It is believed that the results obtained are of general application to the whole group of the Calymenidæ or at least provide a basis for further research. Perhaps not the least interesting of these results is the discovery that certain species had wide geographical range but apparently a comparatively short existence. Such species are valuable for purposes of correlation over extensive areas.

The mode of preservation of the trilobite test has a marked effect upon the ease of identification of specimens. The complete preservation of the dorsal test is relatively infrequent in the geological sequence of the British Isles. The greater proportion of the material is in the form of separated pieces representing the scattered portions of the cast tests or the broken remains of the test after death. This scattering of the parts often makes identification difficult.

II. Preservation of Material

In limestones and some calcareous deposits, such as the Silurian limestones of Dudley, Worcestershire, and the Ordovician calcareous grits of Hoar Edge, Shropshire, the test is preserved almost in its original condition. In some specimens the ornament is preserved in every detail, though too often it has been destroyed by the acid used to clean away the matrix. The best method
The Green Ammonite Beds of the Dorset Lias
Authors: Lang William Dickson
Published: October 2009

I. Introduction.

The Green Ammonite Beds comprise those horizons of the Dorsetshire Lias which lie above the Belemnite Stone—horizon of
Beaniceras
—and below the Three Tiers—nearly the lowest limit of
Amaltheus
. They bear this connotation in the memoirs of the Geological Survey, and include a greater thickness than was intended by Day (1863, p. 291), who first coined the term for 18 feet of clays lying in the lower part of the series as here defined, and yielding nodules in which the typical green ammonites are to be found. The chambers of these ammonites are often filled with greenish calcite—hence the vernacular name.

The Green Ammonite Beds form part of the Upper Lias Marls of De la Beche's earlier account (1826), and the middle part of the “marls and slaty marls with several beds of indurated marl and earthy limestone in the lower part, micaceous in the higher—350 ft.” of his later account (1839, p. 223). They are the equivalent of Oppel's “Davöi-bett”, or “zone des
Amm. Davöi
” (Oppel, 1856–8, pp. 117, 126–9, 148, 151) and he records their occurrence on the Dorset coast (p. 129) as follows: “An der Küste von Charmouth bei Lyme Regis (Dorsetshire) fand ich dagegen nicht allein ein grosses und deutliches Exemplar von Amm. Davöi [also recorded on p. 161], sondern in seiner Begleitung auch die in Schwaben mit ihm zusammenliegenden characteristischen Arten: Amm. capricornus, Henleyi [also recorded on p. 164], Belemnites umbilicatus [also recorded on p. 154], elongatus [also recorded on p. 152], clavatus [also
On the Sliding or Slumping of Submarine Sediments in Denbighshire, North Wales, during the Ludlow Period
Authors: Jones Owen Thomas
Published: October 2009

In a paper published by the Liverpool Geological Society in 1932, Professor P. G. H. Boswell directed attention to an area in the neighbourhood of Llangerniew in north-western Denbighshire wherein structures of great geological interest are exhibited. The area forms part of the Denbighshire Moors, the geology of which has been described by the same author and others (Boswell 1926, 1928 a, b, 1932, 1935 a, b; Boswell and Double 1934). Members of the Geologists' Association visited the region under the guidance of Professor Boswell during the Easter excursion, 1935, and in connexion with that visit a general account of the geology of the region was published, followed by a report of the Field Meeting (Boswell 1935
a, b
).

My active interest in the area was awakened on reading these last two papers and studying some of the excellent photographs by which they are illustrated. They recalled other occurrences of apparently similar structures in this country and in North America. Professor Boswell states (1932, p. 31) that the Denbighshire structures were due to “obviously post-Caledonian” movements, whereas the structures which I had seen in other areas seemed to me to be demonstrably contemporaneous with the deposition of the rocks among which they occur. A further examination of the problems presented seemed therefore desirable. During a brief visit to the area in August 1935, I saw what I considered to be conclusive evidence that the structures near Llangerniew were contemporaneous with the deposition of the Lower Ludlow rocks which exhibit them,
The Volcanic Rocks and Minor Intrusions of the Cross Fell Inlier, Cumberland and Westmorland
Authors: Hudson Stanley Nicholl
Published: October 2009

The Cross Fell inlier consists mainly of Lower Palæozoic rocks and is situated on the eastern side of the Vale of Eden. It was first described in detail by Nicholson and Marr (1891) and has recently been the subject of a further study by Mr. F. W. Shotton (1935). The former authors considered the stratigraphy of the region, while Mr. Shotton has been concerned with the revision of the stratigraphy and the tectonics.

The object of my work, which commenced in 1929 on the suggestion of Professor A. Gilligan, was to map the volcanic rocks and intrusions, describe their petrographical characteristics, and elucidate their stratigraphical relations. More than 300 thin sections of the volcanic, pyroclastic, and intrusive rocks have been made and studied in detail. The mapping is based upon initial field examination, microscopic diagnosis of specimens collected, and then re-examination in the field. This study has led me to conclusions which differ somewhat from those formed by Mr. Shotton (1935). In view of the many small intrusions in the Guns Fell area (Fig. 4), a distinction has been shown between the Skiddaw Slates of Ellergill type and those which have many interbedded sandstones (so thin as to simulate small intrusions). Mr. Shotton appears to have confused these sandstones with felsitic intrusions or tuff bands. Thin sections reveal them to consist of clastic quartz exhibiting strain shadows, with occasional fragments of hard slate. These sandstones reflect shallower conditions of deposition, a more littoral facies not met with elsewhere in the
The Higher Ludlovian Rocks of the Built District
Authors: Straw Stephen Henry
Published: October 2009

The rocks to be described in this paper occupy an area of about 22 square miles in the counties of Radnorshire and Breconshire, which includes the Wye valley between Builth and Erwood station and the hilly ground south of Builth. It is represented on the following six-inch Ordnance Survey maps: Brecknock XI N.E. (Radnor XXXI N.E.), XI S.E., XII N.W. (Radnor XXXII N.W.), XII S.W. (Radnor XXXII S.W.), XV N.E., and XVI N.W. (Radnor XXXV N.W.). The latest geological maps are those of the Geological Survey, Old Series, No. 56 S.W. (1850) and 42 N.W. (1845, with additional Silurian hues in 1855 and 1856).

The strata form an apparently continuous succession, mainly of shelly mudstones and shales, between the graptolitic shales of the zones of
Monograptus
nilssoni and
M. scanicus
and the unfossiliferous green marls at the base of the Old Red Sandstone. The faunal succession remains constant throughout the limited area under consideration, but the stratigraphical distribution of many of the common species differs from that of the classical region of Shropshire. The absence of the Aymestry Limestone and such characteristic members of its fauna as
Conchidium knighti
and
Strophonella euglypha
is a further point of difference. In view of such differences it has not been possible to adopt in its entirety the well-known classification proposed for rocks of the Ludlow district (Elles and Slater 1906, p. 198). There is in central Wales, however, such an extensive development of Ludlow sediments of the type displayed to good advantage in
The Western Part of the Criffell–Dalbeattie Igneous Complex
Authors: MacGregor Malcolm
Published: October 2009

The Criffell—Dalbeatbie complex, which is the largest of the Galloway “granites”, was first described by Peach and Horne (Horne and others 1896, pp. 22–8, 41–57). A general description of these “granites” was incorporated in the memoir on “The Silurian Rocks of Great Britain” (Peach and Horne 1899, pp. 607–31 ). Three of these masses have received further study in recent years : Loch Doon, by Gardiner and Reynolds (1932); Cairnsmore of Carsphairn, by Deer (1935); and Cairnsmore of Fleet, by Gardiner and Reynolds (1936). The western part of the Griffell—Dalbeattie mass is re-examined in the present paper.

The rocks of this district are fairly well exposed on the hill-sides and along the shores, but extensive areas are covered by raised-beach deposits, alluvium, glacial drift, and by the sand and mud of the Solway. Much of the low ground is under cultivation, but bare rock surfaces are common on the high ground culminating in Bengairn (1275 feet), and on the rocky peninsulas of Torr and Almorness.

The metamorphosed sedimentary rocks of the aureole and associated intrusions of porphyrite form high ground to the north and west of the plutonic outcrop. On the southern side they form the sea-cliffs which have been breached by the Bay of Auchencairn and the estuary of the river Urr.

The distribution of the various rocks is shown on the accompanying map (Pl. XXX). The plutonic rocks comprise three granodiorites and a quartz-diorite. The granodiorites are either in direct contact with the quartz-diorite, however,is variable and near
The Etive Granite Complex
Authors: Anderson John Graham Comrie
Published: October 2009

The granite complex of Etive is one of the largest in Britain. It is for the most part surrounded by Dalradian schist, but invades the Lower Old Red Sandstone lavas of the Glen Goe area. It is universally accepted as of Lower Old Red Sand-stone age. It occupies an elliptical area of very high and rugged ground bounded, roughly speaking, by the Pass of Brander on the south-west, Glen Creran on the north-west, Glen Coe on the north-east, and Glen Strae on the south-east (Figs. 1, 2). The longer axis of the ellipse lies in a north-easterly direction and measures some 18 miles, while the shorter axis measures about 10 miles. The total area is about 140 square miles. The rocks of the complex outcrop at sea-level for 10 miles along the shores of the fjord-like Loch Etive and rise to over 3500 feet in such well-known mountains as Ben Gruachan, Ben Starav, and Glach Leathad. Almost the entire area falls within one-inch sheets 45 and 53 of the Geological Survey (Scotland).

The earliest geological account of Ben Gruachan was given by MacCulloch (1817). He describes the granite of which most of the mountain is composed, noting the pink acid type which forms the two man tops. On Murchison and Geikie's
map of Scotland of 1862 and on Geikie's map of 1892 the
boundaries of the granite area are shown with a fair degree of
accuracy, but no attempt is made to distinguish different
intrusions. This deficiency was soon
Low Levels of the Mediterranean Sea during the Pleistocene Glaciation
Authors: Blanc Albert Charles
Published: October 2009

The difficulties which arise in the course of a study of the oscillations of Pleistocene shore-lines are well known (see Daly 1934, Wright 1937). Epeirogenic movements and tectonic dislocations and flexures on the one hand, and eustatic and isostatic oscillations, which are more directly connected with glacial and interglacial periods, on the other, have affected the positions of Pleistocene shore-lines around all oceans. Each littoral region has reacted differently to these factors, according to the character of its structure, the degree of its tectonic stability, and its geographical position in relation to the
inlandeis
. Even the traces of eustatic oscillations of sea-level, which, undisturbed, would show a constant elevation on all littoral regions, are actually found at different heights above the present sea-level, because tectonic and isostatic movements have interfered with their formation and sometimes altered their original position.

In the Mediterranean, the shores of which have not undergone isostatic movements comparable with those of northern Europe, the Pleistocene shore-lines can be traced at levels which appear to have been determined by local eustatic and tectonic oscillations.

Issel, Gignoux, de Lamothe, Depéret, and others have pointed out the approximate constancy, right round the Mediterranean, of the levels of some of these shore-lines. Depéret has even correlated them with the Atlantic shore-lines of western Europe. Some of these investigations have been based only on morphological evidence and altimetry; in others, these methods have been supplemented by palaeontological and stratigraphical research. Only the latter class can furnish a reliable basis for the
Three Tectonic Problems of the Lulworth District: Studies on the Middle Limb of the Purbeck Fold
Authors: Arkell William Joscelyn
Published: October 2009

Of all the folds thrown up across the Chalk plains of North-West Europe during the Alpine orogeny, the most interesting and the most perfectly exposed is the Purbeck anticline. In the cliffs of the Dorset coast the sea has laid bare all parts of the structure, from the core or crestal region, through the vertical and overturned middle limb and the “foresyncline” (Busk 1929, p. 29), into the foreland, where the Upper Cretaceous rocks are seen reposing with sharp unconformity upon a previously folded and eroded Jurassic foundation.

The general and some special aspects of the fold and its associated faults have been discussed in a previous paper (Arkell 1936). The present paper results from a study of the middle limb, where it is dissected by the sea cliffs of the Lulworth district. These cliffs have long been renowned for their beauty, but their marvellous tectonic features, both great and small, have been neglected, with the result that their value to students of tectonics has not been fully utilized.

The first three parts of the paper attempt a solution of the three most outstanding problems : contortions in the Purbeck Beds, the Purbeck Broken Beds, and the abnormal attenuation of the strata towards Durdle Door. The fourth part offers an interpretative essay and synthesis.

The area dealt with is included in sheet 342 of the Geological Survey one-inch map and sheet 141 of the Ordnance Survey one-inch map.

The contortions in the Purbeck Beds at Stair Hole are illustrated in
The Recognition and Correlation of High-level Erosion Surfaces in Britain: a Statistical Study
Authors: Hollingworth Sydney Ewart
Published: October 2009

The realization that many of the rocks now visible on the earth's surface represent consolidated marine deposits was one of the fundamental steps in the development of the science of geology. Changes in the relative distribution of land and sea implied thereby have long been recognized also from considerations of land forms alone, such as raised wave-cut platforms and drowned ria coasts.

In this country, ancient base-levels of erosion, now elevated, have been described by many authors in districts of diverse topography and geological history. Their recognition has, in general, been by one of two methods of approach. First, there is the identification of plateau-like areas as remnants of a former widespread platform which truncates geological structures at a uniform altitude and corresponds approximately with a former sea-level. The work of Barrow, Clement Reid, Dewey, and others in Cornwall and Devon is a classic example of this line of approach. Secondly, there is the quantitative study of the rejuvenation of rivers due to uplift of the land relative to the sea, and the determination of the older and higher base-levels to which the rivers were formerly graded. The pioneer study of the Towy drainage by Professor O. T. Jones (1924), and later the co-operative labours of members of the Weald Research Committee in South-East England and their extension along the south coast by Messrs. Wooldridge and Kirkaldy (1936) and Mr. J. F. N. Green (1936), exemplify the second method. Quantitative methods of investigating the development of the platforms have, so
The Pleistocene Development of the Severn from Bridgnorth to the Sea
Authors: Wills Leonard Johnston
Published: October 2009

In 1914 I began to study the valley of the Severn, from the entrance of the Iron Bridge gorge downwards, in the hope that a detailed examination of the river terraces and topographic features would throw light on the history of the development of the valley. The results of some of this work were published by the Geological Society in 1924, and I have also described the terraces near the mouth of the Stour (1926). As the work progressed, it became necessary to enlarge its scope and to study the tributary valleys. Here it has naturally varied in intensity, but has in some cases been carried right up to the watersheds, and thus has often involved a study of glacial rather than of river drifts.

Although many of the problems cannot at present be solved, I am convinced that the data relating to the river drifts which have been collected can now be profitably set out.

I wish to record my indebtedness to the work of Dr. Mabel Tomlinson on the Avon valley drifts, which has thrown much light on the history of the Severn. I have also been helped by Miss Deakin (now Mrs. N. Boulton) and Mr. W. C. Reeves, who mapped parts of the Stour and of the Salwarpe valleys respectively and have generously allowed me to use their results. I wish, also, to thank my colleagues at the University of Birmingham (Professor W. S. Boulton, Dr. F. Raw, and Mr. F. W. Shotton) and certain members
Stromatoporoids from the Inferior Oolite of South-West England
Authors: Kellaway Geoffrey Arthur , Smith Stanley
Published: October 2009

Since Tornquist (1900, 1901) drew attention to the presence of stromatoporoids in the Mesozoic rocks, a large number of these fossils have been described from the Secondary formations of Europe, Asia, and North America. The only stromatoporoids so far recorded from the Jurassic or Cretaceous rocks of this country, however, are those mentioned by Mr. K. P. Oakley and Dr. H. Dighton Thomas, who, in their report on Miss H. M. Hutton's collection of Inferior Oolite fossils, state that “among her more recent finds there are several specimens of an undescribed species of Stromatoporoid” (
Proc. Cotteswold Nat. F.C.
xxvi, 1937, p. 106). The species described in the present paper came under our notice in 1936. It has apparently a fairly wide distribution in the Inferior Oolite, since our specimens range from North Somerset to Oxfordshire. The first example to attract our attention was found by Mr. J. W. Tutcher some years ago, at Stantonbury Camp, near Bath. It was a small, spherical nodule, little more than an inch in diameter, and was presumed to be a calcareous alga, which, to judge from its external appearance, it might very well have been; but a thin section left no doubt as to its nature, and further investigation has shown it to be congeneric with the genotype of
Burgundia
Munier-Chalmas MS. in Dehorne.

Additional examples of the same species were subsequently identified. These included several larger and better specimens among the Jurassic Hydrozoa in the British Museum (Natural History), from Coombe Hill, near
The Bain Boulder-bed: a Glacial Episode in the Siwalik Series of the Marwat Kundi Range and Shekh Budin, North-West Frontier Province, India
Authors: Morris Thomas Owen
Published: October 2009

In October 1934, at the western end of the trans-Indus continuation of the Salt Range of North-West India, extensive outcrops of a deposit possessing all the characteristics of a typical boulder-clay were discovered in the middle of the strongly folded and faulted Siwalik series of the Marwat Kundi hills and on the northern slopes of Shekh Budin. The boulder-clay was named the Bain Boulder-bed, after the frontier village nearest to its most conveniently accessible outcrop alongside the frontier road from Bannu to Tank, through the Bain pass.

The occurrence of a glacial deposit in this area and at such an horizon was totally unexpected. Successive studies of Siwalik faunas, made since Falconer's pioneer work, have raised progressively the age of the Siwalik series in terms of the European and American time-scales, but no dating later than Middle Pliocene had been suggested for the thick sandy formation in which the Bain Boulder-bed occurs; neither is there any record of evidence of glacial conditions during the deposition of the Siwalik series (Colbert 1935, p. 11). Prior to the discovery of the Bain Boulder-bed, the age of the formation enclosing it had been regarded as Upper Miocene, following Pilgrim (1913), or Middle Pliocene, following Matthew (1929).

The nearest place to Shekh Budin at which fossils had been collected from the formation was the type locality of Pilgrim's Nagri fauna (1913, pp. 267, 318). That fauna lies in the lower portion of the Nagri outcrop cis-Indus, about 100 miles from Shekh Budin. From Nagri
The Geology of the District around Llansantffraid ym Mechain, Montgomeryshire
Authors: Whittington Harry Blackmore
Published: October 2009

The area to be discussed, lying to the south-west of Oswestry, Shropshire, is bounded on the north and east by Carboniferous and newer rocks. It adjoins on the south-west the Meifod area, described in 1928 by Professor W. B. R. King, and on the south the Welshpool area, dealt with by Dr. A. Wade in 1911. No detailed account of this district has previously been given, but all except the most southerly portion is included in sheet 137 (Oswestry) of the Geological Survey one-inch map, and described in the accompanying memoir (Wedd and others 1929). In the latter, references will be found to published earlier work.

As a result of the present reinvestigation of the Llansantffraid district, the map (Pl. XXXIX), differs considerably from the solid edition of the Oswestry sheet. This is particularly so to the north of Llansantffraid, where Ashgillian rocks have been shown to outcrop over a considerable area previously mapped as Caradocian. The limestones south of Llansantffraid have been shown to be the local base of the Valentian. The object of this paper is to describe the stratigraphy of the Llansantffraid area, with particular reference to the zonal classification of the Upper Ordovician rocks and the nature of the Ordovician-Silurian boundary. Mr. B. B. Bancroft worked out a detailed succession in East Shropshire (1928
a
, pp. 33–41), and claimed that a part of the same succession was present in the Caradocian rocks at Bala, Meifod, Welsh-pool and Glyn Ceiriog (1928
a
, pp. 40–1; 1933, tables). It has been
Some Examples of detailed Structure in Early Pre-Cambrian Rocks of Canada
Authors: Derry Duncan Ramsay
Published: October 2009

The geologist who is assisting a mining company in the search for ore in Pre-Cambrian rocks observes, in the course of mapping and interpreting the geological structure, many details of scientific as well as economic interest. The following paper deals with some of these observations, concentrating on typical structural forms as shown by several examples in northern Ontario and Quebec, and on factors relating to the form of certain intrusions. The field evidence for the features described below comes from three sources: first, from detailed surface mapping; secondly, from the mapping of underground workings in mines; and thirdly, from the “logging” and plotting of geology from diamond drill cores, thousands of feet of which are obtained annually at all the larger mines and on many properties under preliminary surface development. Outcrops are fairly abundant except in areas where post-glacial lakes deposited a thick layer of varved clay or sand. In most places weathering has barely penetrated the smooth and polished surface produced by the Pleistocene ice sheet, so that details of structure are very clearly shown.

An attempt is made below to analyse these structural features of deeply eroded rocks, to deduce the stresses under which they were formed, and to correlate them with the features and stresses prevalent in the upper part of a folded section of the earth's crust as seen in younger mountain systems formed in later epochs.

All the rocks mentioned in the present discussion are older Pre-Cambrian (prior to the ep-Archæozoic interval) with the exception
On Northern Glacial Drifts: Some Peculiarities and their Significance
Authors: Carruthers Robert George
Published: October 2009

Geological conceptions are not always infallible, and it is as well that, on occasion, their foundations should be examined with some care. Probably they will prove to be sound, but there is always the possibility that some grave defect or omission may be discovered. From such a scrutiny the present communication has resulted: it is concerned with the origin of those major components of our glacial drifts, the boulder-clays and their interstratified sediments.

The orthodox view on these matters is well known and widely accepted. Ever since the land-ice
versus
submergence controversy died down, boulder-clay (or till) has been regarded as “ground-moraine”, with or without englacial detritus—in exceptional cases as englacial detritus alone—while the sediments indicate periods of recession, of deglaciation. If there is a multiple series of these drifts, then each successive till marks a readvance, however slight, and eventually we get a record of ice-front oscillations, as so frequently happens with modern ice-sheets.

The consensus of opinion is remarkable, not only in this country, but abroad. The one serious trouble seems to be over the extent and duration of the recessions. The monoglacial school hold that they were too brief and too slight to be considered interglacial, but of late years the multiglacialists have gained ground, having received support from many quarters.

Such is the view, embodied in the vast majority of publications; as with most general statements, it needs qualification. More than sixty years ago, Goodchild (1875) held that the drifts in his northern Pennine area were
The stratigraphy and faunal succession in the Ordovician rocks of the Builth-Llandrindod inlier, Radnorshire
Authors: Elles Gertrude Lilian
Published: October 2009

This work is based largely on maps and collections of fossils made between the years 1904 and 1906 by Miss C. Chamberlain, M.Sc., of the University of Birmingham and Newnham College, Cambridge. Miss Chamberlain learned her geology at Cambridge, and then went home to Birmingham and carried on research in the subject under Professor Lapworth. She had hoped to present the results for her Ph.D. degree at Birmingham University, but unfortunately was obliged to leave Birmingham before the work was completed, and it has remained in its original state. A few years ago, when I was again taking up my work on the Ordovician faunas, I wrote to her and asked permission to study her collections. She replied, most generously placing all her maps and collections unreservedly at my disposal. When these came into my possession it was obvious that the collections contained some interesting and valuable material, and with the sanction of Professor Wills I decided to work it up. In the checking and revision of the maps I have had the help of Miss K. Prendergast, Ph.D. M.Sc., of the University of Western Australia and Newnham College, and my pupil Miss Nancy Kirk of Newnham College, who also revised and completed the mapping of the Llandegley Rocks area. These two have given me great help in the collecting of fossils from many localities, and we have been able to make considerable additions to Miss Chamberlain's lists. I have also, with the sanction of Professor Boulton, incorporated some hitherto
The leucite-bearing rocks of the West Kimberley area, Western Australia
Authors: Wade Arthur , Prider Rex T.
Published: October 2009

Introduction

The presence of leucite-bearing rocks in the West Kimberley area of Western Australia is first mentioned by Farquharson (1920, p. 42, and 1922, p. 56). They appear to have been noted first in the basin of the Fitzroy River by Blatchford and Talbot and in the proximity of the Lennard River by Wells (Simpson 1925, p. 59).

Wade (1924, p. 9 and map) refers to these occurrences and shows their position on a geological map of the northern parts of Australia. Simpson (1925, pp. 58–9) describes specimens collected by Blatchford and Talbot and by Wells from “Barjar” (referred to in this paper as “Dadja”) Hill and Mt. North, gives an analysis of the Barjar Hill rock and draws attention to the peculiarities of mineral and chemical composition of these rocks. A report by one of the research committees of the Australasian Association for the Advancement of Science embodies extracts from Simpson's paper and a preliminary description by Skeats (1928, pp. 42–6) of specimens collected by Wade from P Hill and Bruton's Hill (described as “Hill C48,” 20 chains north from Brunton's Bend). An analysis of the rock from P Hill and of a silicified type from Bruton's Hill are included. The report states that eleven separate vents have been recorded from this area, and the occurrences are linked with the leucitic rocks of Sumbawa, Java, Celebes and Borneo.

Blatchford (1927, pp. 20–1) gives a list of the nine occurrences known to him, but does not mention Mt. North, previously
The Carboniferous Limestone of the Castleton-Bradwell area, North Debyshire
Authors: Shirley J. , Horsfield E. L.
Published: October 2009

This paper raises the whole question of correlation of the Derbyshire Lower
Carboniferous with similar beds in the North Western area of sedimentation. From detailed unpublished work upon the Craven Reef Belt I should place the B
2
zone as the direct equivalent of D
1
as defined in that region. It is clear from the present paper that the succession of events in the two basins was very similar as regards facies changes, and the correlation between the two resolves itself into the question of reliability of coral-brachiopod zones as time indicators against that of goniatites. Similar sequences in the two areas may result from a parallel series of facies changes not necessarily synchronous. That this is in part the case may be inferred from the behaviour of
Davidsonina septosa
bands in the two areas. In Derbyshire there are two bands widely separated, whereas in Yorkshire there is often but one band, and where two are seen they are never more than 30 feet apart. It would seem preferable, therefore, to base correlation between the two series upon the goniatites, having complex hard parts and behaving as a rapidly evolving stock, though of limited
phasal distribution, rather than upon the relatively simple skeleton of corals and brachiopods,
equally phasal in distribution, and evolving at a much more leisurely rate. The whole question is
far too large for a short contribution, but it seems desirable to bear the above considerations in
mind when comparing such similar succession in separated areas.
Field relations of certain of the basic igneous rocks associated with the Carboniferous strata of the Midland counties
Authors: Marshall Charles Edward
Published: October 2009

I. I
ntroduction

T
he
basic igneous rocks associated with the Carboniferous strata and especially with the Coal Measures of the Midland counties have long attracted the attention of geologist and miner. The interest of the former has been largely academic; to the miner, the maleficial or beneficial effect of the igneous sheets on the coal seams has been a matter of practical concern. The principal exposed masses are those of Rowley Regis, Wednesfield, Barrow Hill, Pouk Hill, Shatterford, Kinlet, Titterstone Clee, Clee Burf, Brown Clee and Little Wenlock. In many of these districts extensive sills and dykes apparently related to the surface masses have been proved in mining operations.

Each of the surface masses has been at different times interpreted as intrusive or extrusive, but until the comparatively recent accounts of Dr. R. W. Pocock the later tendency had been to regard them as intruded sheets. In two papers field evidence has been presented (Pocock 1926, 1931) to support the suggestion that, with the exception of Wednesfield, Pouk Hill and possibly Barrow Hill, the Midland “basalts” are volcanic. Recent examination of these rocks and associated sediments, however, has made it desirable to reopen the question of the mode of occurrence of certain of the sheets. The evidence discussed in this paper is concerned almost entirely with the field relations of certain of the igneous bodies. Penological investigation of the “basalts” has also provided a considerable amount of interesting material which it is proposed to discuss in later
A gabbro-granodiorite contact in the Slieve Gullion area and its bearing on Tertiary petrogenesis
Authors: Reynolds D. L.
Published: October 2009

Dr. Reynold's excellent paper is welcome as extending to British Isles the recognition of certain phenomena that have often been overlooked in describing the intrusion of basic into acid igneous rocks. Dr. Richey has expressed the hope that " the author's discoveries will be followed up in other cases, perhaps from other countries ", so it may be well to point out that similar observations have been recorded from Rhodesia and South Africa generally over a period of more than thirty years. The first of these appeared in the
Geological Magazine
for January, 1911, under the title of " Observations on some basic dykes and their bearing on certain problems of rock genesis ". The Irish rocks show the initial stages of the processes there described, their features being similar to those of the smaller of the two intrusions into the Matopo granite referred to in my paper. The fact that the quartz of the invaded rock is " usually surrounded by a rim of fine-grained material" is noted, and is illustrated in fig. 2, which also shows the clouding, motting, and granulation or "reticulation" of the felspars due to thermal alteration. A minor difference is that " between the quartz and felspar grains there is always a reaction rim 1/10 mm. broad ". In the larger intrusion at Kahlele's, which is more gabbro-like than Dr. Reynolds's rock, though I still prefer to call it a dolerite, secondary micropegmatite is developed on a large scale and in extreme cases forms
Igneous Rocks from the Central Libyan Desert
Authors: Tomkeieff Sergei Ivanovich , Peel Ronald Francis
Published: October 2009

T
he
specimens described and discussed by the senior author in this paper comprise the most interesting members of a general collection made by Mr. R. F. Peel while accompanying Major R. A. Bagnold's 1938 expedition into the Libyan Desert. The general account of the Travels and work of this expedition has already been given (Bagnold and others 1939) and details need not be repeated here. It is sufficient to state that most of the two months’ stay in the desert was spent in the extreme south-west of Egypt and the adjoining parts of Libya and the Sudan, in the neighbourhood of the Gilf kebir plateau and Gebel Uweinat. No specific geological work was planned by the expedition, but in the course of exploration and survey new discoveries were made, mainly of volcanic plugs and craters. The sedimentary rocks collectd have, on examination, yielded no new features of particular interest, and, with the exception of certain contact-metamorphosed sandstones, no mention of them will be made here.

I. G
eneral
G
eology and
T
opography of the
R
egion

T
he
fullest description of the geology of this part of the Libyan Desert is given by K. S. Sandford (1935a, b). Geologically, the region is dominated by the sandstones, pebble-beds and occasional shales of the Nubian Series. These formations, of doubtful age, but probably mainly Mesozoic (Sandford 1935a, 1937), are distubed by local folding and warping, particularly around Gebel ‘Uweinat, but over great areas are horizontal. The prevailing topography is in harmony with this simple structure: level
Dasycladaceous Algae from the Girvan area
Authors: Currie Ethel D. , Edwards Wilfred Norman
Published: October 2009

The genus
Mastopora
, originally instituted by Eichwald in 1840, though not figured until 1860, was recognized as an alga by Stolley (1896), who gave a very full and clear account of it and of the allied genera
Coelosphaeridium, Cyclocrinites
and
Apidium
, mainly founded on material from Ordovician rocks of the Baltic region. Stolley showed that Salter's problematical
Nidulites
(1851) was identical with
Mastopora
; he therefore transferred to the latter genus Salter's
N. favus
from the Lower Llandovery of Mulloch Hill, Ayrshire, and also, with a query,
N. parvus
from the Upper Ordovician of Balclatchie. The latter had been only tentatively named by Nicholson and Etheridge (1878, p. 18), was merely stated to be smaller than
N. favus
, and was not figured. This species has remained undescribed to the present day, while the identification of
Nidulites
with
Mastopora
and its recognition as a calcareous alga have been largely overlooked by palaeontologists. Nicholson, indeed (1889, p. 188), with material of Eichwald's
Mastopora concava
in his hands, had realized the identity of the two genera, though he was under the impression that Salter's name was the earlier, and he had even commented on the resemblance of the specimens to the Siphoneae Verticillatae (= Dasycladaceae). Both of the Girvan species were definitely included in
Mastopora
by Pia (1927).

The main purpose of the present communication is to figure and describe these two algae from the Girvan district. Most of the material is in the Mrs. Robert Gray collection, now in the Geological Department of
The Cheviot Granite
Authors: Jhingran Anant Gopal , Tomkeieff S. I.
Published: October 2009

I. I
ntroduction

T
he
Cheviot granite is situated in Northumberland close to the border between England and Scotland. It has beeb known in geological literature as a unique example in the British Isles of an augite granite. The present investigation was undertaken with the object of studying details of variation in the granite and its relations with the adjacent lavas, and of determining whether the basic character of the granite is attributable to its contamination by the adjacent andesitic lavas.

Although the Cheviot Hills have long attracted naturalists and geologists, the amount of literature on the petrology of the granite is limited. Winch (1816) first noticed the occurrence of " porphyritic syenite and granitic syenite ", and Tate (1867) described the igneous rocks of the district in a little more detail. Clough (1882) discussed the distribution, composition, and some of the mineral and textural varieties of the granite. The first account of its petrology appeared in 1885, when Teall described the rocks he collected during a day's traverse across the Cheviot Hills. In 1888 the Geological Survey published a geological map of the district, together with a memoir (Clough 1888). This was followed by a paper by Kynaston (1899), who made a fairly exhaustive study of the granite, recorded the chief features of the rocks and discussed the genentic relations between the lavas, the granite, and the dykes. Subsequently, the area remained almost untouched until 1932, when the Geological Survey issued revised geological maps (sheets 3 and 5) and a memoir on “The
Stratigraphy and Structures East of Oxford. Part III: Islip
Authors: Arkell William Joscelyn
Published: October 2009

The area consists of Bathonian and Callovian rocks—Great Oolite White Limestone, Forest Marble, Cornbrash, Kellaways Beds and Oxford Clay—with some-river gravel and much alluvium. The area lies upon the north-westerly continuation of the northwest-striking folds and faults of intra-Cretaceous age described in two previous parts of the paper. In addition, this system is intersected by an anticline having a north-easterly strike, and both are cut by west-north-westerly faults. An attempt is made to unravel the resulting structures in detail.
The Ordovician Rocks of Arvon
Authors: Greenly Edward
Published: October 2009

The Ordovician of Arvon lies between that of Anglesey and that of the mountainland of Snowdonia. Brief petrological studies are made. The zonal succession is much restricted, for five of the higher Ordovician zones are missing. An interesting faunal feature is the richness of the Extensus Zone in
Azygograptus eivionicus
. The total thickness of the succession is rather more than 2500 feet. The base of the Extensus Zone sweeps unconformably across all the older systems. The Ordovician facies is marine, like that of Anglesey, the Volcanic Series of Snowdon having probably thinned away before it reached as far north as Arvon. Reasons also are adduced for supposing that all the higher zones have been swept away by waste. The curvature of the Ordovician boundaries indicates extensive thrusting. One or two thrusts are visible, a section in an abandoned mine adit proving that the Arvonian rhyolite has been driven, horizontally, over Ordovician shales. The several Ordovician tracts are briefly described.
Notes on the compressibility of clays
Authors: Skempton Alec Westley , Jones O. T.
Published: October 2009

The consolidation of an argillaceous sediment may be simply described as the process by which it is compressed from a mud into a clay and finally, if the weight of the overburden is sufficient, into a shale.
1
This process is of importance in the interpretation of geological structure, and on a smaller scale it has an application in the design of foundations for engineering structures, since the weight of a structure founded on clay will cause settlements due to consolidation, and the magnitude of these settlements must be know.

The practical aspects of consolidation have been considered in several papers in geological and engineering literature. In the present paper we shall be concerned with a quantitative study of the process of consolidation in argillaceous sediments, and the objects of our investigation will be as follows: (1) to examine the compressibility of a number of different types of clay, as demonstrated in laboratory consolidation tests; (2) to present field data on the compressibility of clays in nature; (3) to compare the ture compressibility of clays in nature with that found in the laboratory tests.

The first experimental work on consolidation was published by K. Terzaghi in 1921 and 1923. This was collected together and considerably expanded in the book
Erdbaumechanik
which was published in 1925 and which formed the basis of the new applied science known as soil mechanics. In 1927 the same author gave results of laboratory consolidation tests on several different clays and showed that the compressibility was greater
On the Lower Carboniferous corals:
Rhopalolasma bradbournense
(Wilmore) and
Rhopalolasma Rylstonense
sp. Nov.
Authors: Hudson R. G. S.
Published: October 2009

Professor A. E. Trueman welcomed the graphical exposition of the variation in size and form in
Rhopalolasma
. He accepted the author's explanation of differential growth-rates, but inquired whether any measurements of the diameter of the corallum had been made, or of the stages at which a given diameter was reached; it would be useful to know whether any correlation existed between these variables. The two species described, and their variants, seemed to illustrate very neatly the features of a species-plexus, and he hoped further work would be done on the material.

Dr. H. Dighton Thomas entirely agreed with the author's solution of the taxonomic problem of what is the type specimen of
Rhopalolasma bradbournense
. He pointed out that many systematists would consider the evidence produced by the author to established
R. bradbournense
and
R. rylstonense
as two species to be conclusive proof that they were only variants of one species. He suggested that in many corals, such as some simple hexacorals, there was tendency for variation in the septa to be confined to certain sectors only. He asked whether the very elongate forms described by the author showed deeper calices with shorter septa than did those of younger individuals.

Dr. Stanley Smith welcomed the introduction of analytical methods into coral studies. He asked Dr. Hudson whether the cyathaxonid form of septal insertion was complete or only partial. He also asked whether the cylindrical forms among the corals Dr. Hudson described were straight or twisted. Commenting upon the large number of