bluuebunny/crossref_metadata_2025 huggingface dataset:
A Composite Sill at Newton Abbot (Devon)
Authors: Shannon William George St. John
Published: October 2009

I. Introduction.

The sill which is described in this paper forms the summit and part of the northern flank of Knowles Hill, Newton Abbot, 6-inch Ordnance-Survey Map 109, S.E. The hill is bounded on all sides except the western by the alluvium of the Teign and its tributary the Lemon; it forms a prominent hog-back lying in the fork between the two rivers. The base of the hill is formed of Upper Devonian slates, and these are continuous to the west, where, at a distance of about half a mile, another outcrop of dolerite occurs at High week Church. The occurrence of picrite was discovered by Busz, and a short description of the sill and of the presence of original quartz is given in the Geological Survey Memoir on the ‘Geology of Newton Abbot,’ No. 339, 1913.

II. Field Relations.

The summit of Knowles Hill has been quarried, and a smaller quarry exists by the footpath on the north of the hill, bordering the Teign alluvium. The rocks described are mainly from the upper quarry. The northern slopes of the hill are in pasture, and the exposures are too weathered to admit of a petrographic description of the rocks; on the east, the geological lines have been drawn from very limited exposures, as the area has been completely built over. The sill is intrusive into Upper Devonian slates; its lower boundary is indicated by the fact that the floor of the quarry is in slates, the whole of the sill
On a Collection of Carboniferous Plants from Peru
Authors: Seward Albert Charles
Published: October 2009

In the course of a geological expedition to Peru in 1911 Mr. J. A. Douglas collected some fossil plants from coal-bearing strata on the south side of the peninsula of Paracas, a few miles south of the port of Pisco (lat. 13° 45′ S.). The plants, which are the property of the Geological Department of Oxford University, were handed to me for identification by Mr. Douglas, who also supplied information on the geology of the district. The specimens, though fragmentary and few in number, are worth recording, since this is the only known occurrence of fossiliferous Palæozoic rocks on the coast of Peru. Moreover, from a phytogeographical point of view, any fossil plants from South America are worthy of attention.

The coal occurs in a series of greenish sandstones and grey and black carbonaceous shales, which have a north-easterly strike and dip about 25° south-eastwards. These are overlain unconformably on the neck of the peninsula by Tertiary sandstones and impure limestones. There is no definite stratigraphical evidence of the age of the coal-bearing beds, and the plants are therefore of special importance: in other districts the strata which are the chief source of Peruvian coal are Mesozoic in age. Mr. Douglas informed me that the rocks in question were described by Friedrich Fuchs, who published a note on them in 1900 in the ‘Boletin de Minas’ (Lima). Fuchs recorded the following species, and assigned the beds to the Upper Coal Measures:—

Calamites Suckowi
Brongniart. C.

Sphenopteris Hartlebeni
Dunker. W.

Baiera
Notes on the Phosphate-Deposit of Ocean Island; with Remarks on the Phosphates of the Equatorial Belt of the Pacific Ocean
Authors: Owen Launcelot
Published: October 2009

I. Introduction

Within the tropical belt of the Pacific Ocean occur several islands containing deposits rich in calcium phosphate. The majority of these islands are situated within 10° of the Equator, and between longitudes 140° E. and 180° E.

At the present day, the islands the deposits of which may be considered as of commercial importance are Angaur, Makatea (near Tahiti), Nauru, and Ocean Island. Other islands, most of which have been worked in the early days of the phosphate industry, are Baker, Howland, Phoenix, Sydney, Maiden, Christmas, Flint, Starbuck, Browse, Lacépeède, Laysan, Cornwallis, and Clipperton.

Although from time to time various theories have been put forward as to the origin of these phosphate deposits, there can be no reasonable doubt that they are all due, primarily, to bird-droppings.

With the one exception of Clipperton Island, the deposits consist entirely of more or less leached guano overlying a coral-floor which is, to a greater or less extent, changed by metasomatism into tricalcium phosphate. The deposits mentioned as being of commercial importance have been leached so completely that the soluble phosphates have entirely disappeared, some of the phosphate on Ocean Island, for example, containing over 90 per cent. of tricalcium phosphate (Ca
3
P
2
O
8
). On Malden Island, where the birds still congregate, all three forms of calcium phosphate (CaH
4
P
2
O
8
, CaHPO
4
, and Ca
3
P
2
O
8
) are found; while on Clipperton Island a mass of trachyte, about 60 feet high, rises through the coral in the south-eastern part of the island. The original structure of the trachyte
The Igneous and Associated Rocks of Llanwrtyd (Brecon)
Authors: Stamp Laurence Dudley , Wooldridge Sidney William
Published: October 2009

(1) Introduction

North of the little town of Llanwrtyd Wells lies an oval patch of igneous rocks, about 3 miles long and half a mile broad. It has long been known that these rocks occupy the core of an anticline—that of the Vale of Towy—which strikes approximately north-north-east and south-south-west. Some years ago I visited the igneous rocks in the neighbourhood of Builth (described by Mr. Henry Woods in 1894). It has usually been presumed that the igneous rocks of Llanwrtyd, which locality is about 10 miles west-south-west of Builth, are of the same age as those near the latter town. Accordingly, in order to test the truth of this belief, a survey of the Llanwrtyd rocks was begun. It was found that the igneous rocks differed considerably from those near Builth, but at that time no palsæontological evidence of their age was found. In 1920, while studying the Siluro-Devonian junction in Central Wales, I took the opportunity of revisiting Llanwrtyd Wells for the purpose of completing the mapping of the igneous rocks and Ordovician sediments. I was accompanied on this occasion by Mr. Wooldridge, who has undertaken the petrological description of the rocks.

(2) Previous work

The literature relating to this district is scanty. The only description is that given by Sir Roderick Murchison. He states that the presence of mineral springs at Llanwrtyd Wells led him to suspect the presence of igneous rocks in the neighbourhood, and his investigations proved that such rocks did occur. His account occupies
Oligocene Mosquitoes in the British Museum; with a Summary of our present Knowledge concerning Fossil Culicidæ
Authors: Edwards Frederick Wallace
Published: October 2009

In 1916 Prof. T. D. A. Cockerell described some fossil mosquitoes in the United States National Museum, from the Oligocene of the Isle of Wight. The material that he described consisted only of duplicates from the Brodie Collection, the main portion of which remained in the Geological Department of the British Museum (Natural History). When Prof. Cockerell came to England in 1920, he undertook the study of the main Brodie Collection of fossil insects, and found in it a considerable number of mosquitoes; at his suggestion I readily undertook to work out this material, and I wish to express my indebtedness to him for assistance and advice. My thanks are also due to Dr. A. Smith Woodward, F.E.S. and to Dr. F. A. Bather, F.E.S., for the facilities which they have afforded me. The descriptions and figures of Cockerell not being entirely clear, Dr. Bather obtained from Dr. R. S. Bassler, of Washington, photographs of the types of CockerelFs three species. These are reproduced here (PI. VII), and have been of great assistance in deciding upon the synonymy.

As explained by Prof. Cockerell in a recent paper, the material examined belongs in part to the British Museum and in part to the late Mr. R. W. Hooley, F.G-.S. In the descriptions which follow, specimens belonging to the Museum are referred to by the letter I and their register-number, those belonging to Mr. Hooley (but deposited at the Museum) by the letter H. All the material is from G-urnet Bay (Isle
Appendix—On Ammonites from New Zealand.
Authors: Spath Leonard Frank
Published: October 2009

(1) Introduction

Dr. Trechmann, who had been favoured with identifications from Mr. S. S. Buckman, at first had the intention of dealing in the foregoing paper with some of the ammonites that he had collected in New Zealand ; but, at his request, I have undertaken, in this appendix, a description of a larger series of ammonites, incorporating therewith observations on certain :New Zealand specimens long since acquired by the British Museum (Natural History) and others sent recently by :Prof. P. Marshall and the Geological Survey of New Zealand. The examples originally forwarded by Dr. Trechmann included five belonging to the genus
Psiloceras
, of the Lower Lias, and five ammonites from the Upper Jurassic, representing the genera
Phylloceras, Uhligites
, and
Aululacosphinctes
'. In addition there were an unidentifiable fragment of probably an Upper Jurassic ammonite, from Kohai Point, and several Senonian forms, already briefly mentioned elsewhere
1
; further, a Jurassic
Phylloceras
and a
Lytoceras
belonging to Prof. Marshall.

The Liassic ammonites in the British Museum, described below, belong to the genera
Phiylloceras, Rhacophyllites
, and
Lytoceras,(Thysanoceras)
. There is no detailed information available with these specimens, the matrix of which is a hard, dark-green rock, exactly like that of one of the Upper Triassic
Pinacoceras
recorded by Dr. Treehmann,
2
or of the Hettangian .
Psiloceras
. These had ,been bestowed among Neocomian ammonites, perhaps on account of the green matrix, the
Lytoceras
fragment being labelled '
Crioceras
.

With them was the indeterminable impression of an ammonite in an unlocalized, similarly hard, compact, dark-green rock. Two .additional examples
The Charophyta from Clacton-on-Sea
Authors: Groves James
Published: October 2009

The fruits vary considerably in size and shape, and represent in my opinion two, or possibly three, species.

(1) The type to which most of the specimens belong resembles the fruit of the existing British
Chara hispida
, which it may well be. The length of the oogonium appears to be about 800 µ, but none of the full-grown specimens is perfect at the apex; the breadth=about 550 to 600 µ. It is usually broadest about the middle, and tapers slightly towards the base. The spiral cells show some eleven or twelve convolutions.

(2) The single dark fruit is apparently a different species, about the length of the first, though narrower (500 µ), and broadest about the middle but sub-cylindrical; and the spiral cells show rather more convolutions. Another fruit, a lighter-coloured, imperfect specimen, may belong to the same species.

(3) A single light-coloured specimen seems different from both 1 and 2. About as narrow as 2, but less cylindrical, tapering conspicuously at each extremity; length = probably about 82·5 µ; breadth = about 500 µ. The spiral cells would probably show twelve or thirteen convolutions. This might well belong to the existing species
C. fragilis
.

The oospores seem, in all cases, to be well preserved.

The fragments of stem and branches belong pretty certainly to a
Chara
of the section Diplostephanæ Diplostichæ, which includes
C. hispida
and
C. vulgaris
; in thickness they agree more closely with the latter than with the former.
Note on the Rodent-Remains from Clacton-on-Sea
Authors: Hinton Martin Alister Campbell
Published: October 2009

For the greater part these remains are fragmentary and indeterminable ; but some of the teeth, including a right m.

1

¯

, and a fragment of a left m.

1

¯

and a left m.

2

¯

a from Bed
q
, together with portions of two lower incisors from Bed
z
,
belong to a small vole. Of these specimens the right m.

1

¯

is the most important. Possessing, as it does, five closed triangles in addition to the posterior and anterior loops, it is clearly referable to the genus
Microtus
; and in its small size, enamel structure, and form of the anterior loop, it agrees exactly with many of the teeth obtained by Mr. A. S. Kennard and myself long ago, from the brick-earth of Grays Thurrock. The species from Grays is clearly a member of the
M. agrestoides
group, to which I have applied the name
M. agrestoides
; and I have little doubt that the Clacton vole is either identical with, or else very closely allied to, the Grays species.

Mr. Warren has called my attention to the fact that
Arvicola amphibius
has been recorded from Clacton. This apparently rests upon the authority of John Brown, of Stan way, who, in describing his figure
1
of a ‘ Section of a Freshwater Formation near Walton, on the Essex Coast,’ says of Bed 5 :— ‘Peat with subordinate and interrupted beds of marine aud freshwater shells. Incisive tooth of water rat, figured in pi. xi, 2, Reliqu. Diluv.’; and on the following page he says,
Appendix III.—The Pleistocene Non-Marine Mollusca
Authors: Kennabd Alfeed Santer , Woodwaed Bebnaed Bakham
Published: October 2009

The Non-Marine Mollusca of the Pleistocene deposits near Oxford have received but scant attention in the past, and we are greatly indebted to Dr. K. S. Sandford for submitting to us the series found by him during his recent survey of the district. Although the list of species is not extensive, two species are new to science ; and it is evident that further work will add greatly to the number. We hope that this pioneer work is only the prelude to an exhaustive study of these deposits and their fauna.

Dr. K. S. Sandford obtained two species from this deposit: namely,
Unio prestiwichi
sp. nov. and
Sphærium radleyense
sp. nov.

Four species are recorded by John Phillips from Pleistocene gravel at Kidlington, and two species are preserved in the Oxford University Museum. The list will thus be
The Geological Structure of the Clevedon-Portishead Area, Somerset
Authors: Reynolds Sidney Hugh , Greenly Edward
Published: October 2009

The area described in the following paper is, in the main, a prominent ridge some 4 miles long, forming the extreme north-western portion of Somerset and stretching from Portishead in the northeast to Clevedon in the south-west (Pl. XXXIX, fig. 1). It is separated from the Clifton—Clevedon ridge by the Gordano valley; but, as one proceeds south-westwards, the two ridges are seen to approach and eventually come together at Clevedon.

The main part of the ridge is geologically very simple, consisting of Old Red Sandstone overlain by the Carboniferous Limestone Series dipping south-eastwards; but at each end the structure becomes very complicated and difficult of interpretation. Owing to this fact, it has been thought desirable to describe the main part of the ridge first.

The district was mapped by Sanders on the scale of 4 inches to the mile, and the Geological Survey for the 1-inch map made but slight alteration in his lines. Little has been written, except about the Portishead end of the ridge. This, however, was described in considerable detail by Prof. C. Lloyd Morgan, and, as his paper deals fully with the earlier work, it will not be necessary to repeat the references to this subject. Arthur Yaughan's work on the palæontological sequence in the Carboniferous Limestone of the Bristol area led him to determine the horizon of the rocks at the chief exposures throughout the district, but he did not attempt any general explanation of the geological structure. Some account of the chief exposures will
The Upper Towy Drainage-System
Authors: Jones Owen Thomas
Published: October 2009

The most remarkable feature in the physical geography of Wales is undoubtedly the great plateau which extends almost without interruption from near the coast of Denbighshire in North Wales through Central and South Wales, where it occupies a large area of the counties of Cardigan, Carmarthen, Radnor, and probably also of Brecon. It truncates alike the highly folded Lower Palæozoic rocks of North and Central Wales and the gently inclined Old Red Sandstone marls of Breconshire. Its surface is apparently little influenced, either by the attitude of the rocks or by their lithological characters.

It abuts against the mountains of North Wales between Cader Idris and Snowdonia, which in places rise abruptly above its level, while southwards it extends to the foot of the great Upper Old Red Sandstone escarpment of Breconshire and Carmarthenshire, which overlooks it as a line of high cliffs overlooks a level foreshore.

Sir Andrew Ramsay attributed the formation of the plateau to marine denudation, and at one time regarded the escarpment of the Brecon Beacons as an ancient line of cliff.

Occasional references to the plateau occur in later publications. I have given reasons for distinguishing in Central Wales two distinct plateaux: namely, the Higher Plateau described above, and the Coastal Plateau which lies south of the Dovey Estuary and, extending inland from the coast of Cardigan Bay for a distance of 3 to 15 miles, is sharply marked off from the High Plateau on the east.

The Coastal Plateau was attributed to marine erosion
The Fossil Elephants of the Upper Thames Basin
Authors: Sandford Kenneth Stuart
Published: October 2009

Succession of Deposits : Recent Developments.

In a paper published recently in the Journal of this Society (Q. J. G. S. vol. lxxx, 1924. p. 113) I described the river-gravels of the Thames and of its tributaries about Oxford, and, on a considerable body of evidence, suggested the following sequence of events:—

Glacial Plateau Drift; about 140 feet above the present river-level. [‘Glacial’, because, among other things, it contains glacially-striated erratic boulders and pebbles.]

Handborough Terrace; base about 90 to 100 feet above river-level, containing a well-marked ‘
Elephas antiquus fauna
’.

Wolvercote Terrace; about 40 feet above river-level, with derived Chellean implements, no fauna known; placed later than the above on stratigraphical evidence.

Wolvercote Channel; about 40 feet above river-level, a ‘ravinement’ of the Wolvercote Terrace, containing at the bottom unrolled Upper Acheulean and Micoque implements,
Elephas antiquus
and associated animals, capped by sands with mollusca indicative of temperate climate, and at a higher level peat, with plants, mosses, and coleoptera of temperate to sub-arctic character; above are clays containing rare implements, which are suggestive of Mousterian workmanship. At the top the Warp Sands are driven into the underlying deposits, as if by considerable force from above (suggestive of a cold and wet climate).

Summertown-Radley Terrace; about 20 feet above river-level, separated from the Wolvercote Terrace by a step; lower gravels abundant in remains of
E. primigenius
and accompanying fauna (less the Reindeer), overlain unconformably by gravels in which occur Hippopotamus, sometimes abundant,
Corbicula fluminalis
—occasionally very abundant, with valves united and
The Pleistocene Non-Marine Mollusca of the Avon Valley
Authors: Kennard Alfred Santer , Woodward Bernard Barham
Published: October 2009

The most important paper on the Pleistocene deposits of the Avon Valley is by H. E. Strickland. This was sent to the Geological Society in June, 1835, and a brief abstract was published; but the paper was first printed in full in 1858.

As Jardine states, ‘most of the localities mentioned are now either filled up, worked out, or become otherwise inaccessible,’ and it is a matter of congratulation that so careful and competent an observer as Strickland was a resident in the district, while it is noteworthy that but little has been added to our knowledge since. It is, however, necessary to bring our knowledge up to date, and we thank Miss Tomlinson for submitting her specimens for examination; we also thank Mr. W. H. Edwards of the Victoria Institute, Worcester, for similar courtesy, and Mr. Hugh Watson for assistance with the Strickland Collection now preserved at Cambridge.

Fourteen species were obtained from this locality, namely :—

Pupilla muscorum
(Linné). 3 examples.

Limnæa pereger
(Müller). Common.

Limnæa truncatula
(Müller). 2 examples.

Planorbis læevis
Alder. 2 examples.

Ancylastrum fluviatile
(Müller). 2 examples

Valvata piscinalis
(Müller). 2 examples

Bithynia tentacutata
(Linnæ). 1 example

Unio littoralis
Cuvier. 1 valve.

Corbicula fluminalis
(Müller). 6 valves.

Sphærium corneum
(Linnæ). Common.

Pisidium amnicum
(Müller). Common.

Pisidium cinereum
Alder.
The Llandovery Rocks of Garth (Breconshire)
Authors: Andrew Gerald
Published: October 2009

I. Introduction.

The area described in this paper is shown on Sheet 196 (uncoloured edition) of the 1-inch Ordnance Survey map, and on Sheet 56 S.W. of the (Old Series) 1-inch Geological Survey map, and also on the following 6-inch maps:—Brecònshire, viii N.W., N.E., S.W., S.E.; x N.E., S.E.; and xi N.W., S.W.

The district lies north-west of the Irfon, a tributary of the Wye, and mainly in the basin of the Chwefru, which flows southeastwards through the northern portion to join the Irfon near Builth.

Murchison dismisses most of the tract as containing ’hardly a single bed of solid stone’, and compares it with the Radnorshire area, where the ‘Upper Silurian’ lies, without the intervention of the Caradoc and Llandeilo groups, on the ‘Cambrian’. The rocks of Pen cefn-ty-mawr, Allt-y-elyêh, and Dol-y-fan are definitely referred to the ‘Cambrian’. His plate (facing p. 346) illustrates this arrangement, as do also the map and section. In ‘Siluria’ (5th ed. 1872) the strata west of the previous boundary-line of the ‘Lower Silurian-Cambrian’ were included as ‘Lower Silurian’.

The area was first surveyed by the officers of the Geological Survey, W. T. Aveline & Andrew Ramsay, and the map was published in 1850. The section (Sheet 5, Sect. 1), on the scale of 6 inches to the mile, shows the relationships of the Wenlock, ‘Tarannon’ (Pale) Shales, and Upper and Lower Llandovery. The occurrence of ‘sandstones and shales with fossils distinct from those of the Upper Llandovery,
Rhynchonella angustifrons, Atrypa marginalis, Pentamerus undatus
The Relations between the Llandovery Rocks of Llandovery and those of Garth
Authors: Andrew Gerald
Published: October 2009

While we were engaged in examining the districts described in the two preceding communications, we frequently compared notes upon the succession and fauna. These comparisons appeared to show that during the Llandovery Epoch the geological events in one district were reproduced with some exactness in the other. A closer enquiry revealed, however, certain significant differences between the two areas, and, as both the similarities and the differences throw an interesting light upon the earth-movements which affected these areas during the Llandovery Epoch, we believe that it will serve a useful purpose to bring them to the notice of the Society. The observations upon which the comparisons are based are contained in the accounts of the respective areas, except that some additional facts relating to the northern part of the Llandovery district are recorded in this paper and on the map which accompanies it (p. 408).

Both districts lie on the eastern flank of the Towy Anticline, and on the same general line of strike. The rocks belong to the shelly facies, but contain an occasional graptolite. About 5 miles away to the west, the Llandovery rocks of Rhayader and of Ystradffin mark the position of the western flank of the Towy Anticline, but these belong to the graptolitic facies. The axis of that anticline is not situated midway between the eastern and the western Silurian outcrops; it must, in fact, pass within a mile or two west of the base of the Silurian in both the Garth and the Llandovery
On some Occurrences of Spherulitic Siderite and other Carbonates in Sediments
Authors: Spencer Edmondson
Published: October 2009

I. Introduction, and Summary of Earlier Work

Mineral crystallizations possessing a radiate or divergent form are of common occurrence in certain types of igneous rocks, and to a more limited extent in sedimentary rocks. In igneous rocks these structures were first examined and described by H. Vogelsang (1), who gave to them the name of ‘spherulitic structures’, a term which has since been employed by petrologists for these igneous rock-growths in particular and for similar structures in general.

J. P. Iddings (2), in 1891, in a review of these igneous spherulites, pointed out that their essential feature was crystallization outwards from a centre or from a number of neighbouring centres, with a divergent or radiate arrangement, and that any concentric zoning or banding present was incidental to the radiate growth, since such bands or zones become truncated at points of contact with an obstacle, or with an adjacent spherulite.

Dr. Alfred Harker (3), in his ‘Natural History of Igneous Kocks’, discussed these igneous structures, and suggested that they had been formed by relatively rapid crystallization from saturated or supersaturated solutions.

In sedimentary rocks, spherulitic structures occur sometimes in the form of large isolated individuals, and sometimes as colonies of small interfering units. The latter variety which, on the one hand, possesses many of the features of igneous spherulites, appears to pass gradually, on the other hand, by an increase in the amount of zoning or banding, into true oolitic structures.

Modern research in colloid chemistry has brought new facts to
Report on the Non-Marine Mollusca
Authors: Kennard Alfred Santer , Woodward Bernard Barham
Published: October 2009

Botanic Garden Pit, Cambridge.

Fifteen species were obtained from this section, namely :—

Of these, the most interesting form is
Sphærium dickinii
Clessin. We have previously recorded this species from the Pleistocene of Crayford and Barnwell Abbey as S.
mænanum
Kobelt, but Clessin’s name has priority. It is quite unknown from any other of the Pleistocene deposits in these islands. This gravel is probably of the same age as that of Barnwell Abbey.

Milton Road, Cambridge.

We have identified twenty species from this deposit, namely :—

Although no extinct forms were present, it is a typical mid-Pleistocene assemblage, and this deposit is probably of the same age as the gravel of Barnwell Abbey.

Travellers’ Rest Pit, Cambridge.

From the upper gravels of this section three species were obtained, namely :—

It is quite impossible to say anything as to the age of this deposit, except that it may be late Pleistocene.

Bordeaux Pit, Little Chesterford (Essex).

We have identified ten species from this deposit, namely :—

This faunule would appear to indicate rather a late Pleistocene age.

From the Black Gable, Storey’s Way, Cambridge, a valve of
Corbicula fluminalis
(Müller) was obtained at a depth of 3 feet, probably indicating a deposit of the same age as the Barnwell Abbey gravel.

Pear Tree Inn Pit, Hildersham.

From this section we have determined eleven species, namely:—

This deposit is probably of late Pleistocene age.

Manea.

The various pits in the neighbourhood of Manea have yielded the following species :—

All these
The Geology of the Cayman Islands (British West Indies), and their Relation to the Bartlett Trough
Authors: Matley Charles Alfred
Published: October 2009

The Cayman Islands, a small dependency of the British Empire, with a local government controlled by the Government of Jamaica, occupy an isolated position of exceptional interest, both geographical and geological, in the Caribbean Sea. Situated between Jamaica and Cuba, and flanked on the south by the great depression of the Bartlett Trough, which descends over 20,000 feet within 18 miles of the shores of Grand Cayman, they are the only projecting peaks in the submarine ridge that extends from the Sierra Maestra of Cuba to the Misteriosa Bank in the direction of British Honduras. This ridge, though a recognized submarine feature, is irregular, and a depression of 7000 feet lies in it between Grand Cayman and the Lesser Caymans.

The dependency consists of three islands, of which the two smaller, Cayman Brac and Little Cayman, are separated by only 4 miles of sea, while the third, Grand Cayman, is about 60 miles away. Cayman Brac is situated about 125 miles north-west of Montego Bay (Jamaica), and Grand Cayman lies 178 miles west-north-west of Negril Point, the nearest point of Jamaica, and about 150 miles from the Isle of Pines (Cuba). The combined area of the three islands is about 100 square miles. Columbus discovered the Lesser Caymans in 1503, and named them ‘Las Tortugas’, as the shores were swarming with turtle. Grand Cayman was discovered at some later unknown date, and is first recorded in history as being in the occupation of Spanish buccaneers. Europeans appear to have been
On Bolopora undosa
gen. et sp. nov.: a Rock-building Bryozoan with Phosphatized Skeleton, from the Basal Arenig Rocks of Ffestiniog, (North Wales)
Authors: Lewis Herbert Price
Published: October 2009

In the course of many years' map-making and searching for fossils among the cleaved and altered Cambrian and Ordovician rocks which compose the Moelwyns and the Manod, and the Slate-Belt of Blaenau Ffestiniog, Prof. W. G. Fearnsides has noted the almost general occurrence of streaks and nodules of some dark fine-grained, banded, chert-like material in the basal part of certain conglomeratic lenticles or beds, at or near the surface of discordance where Tremadoc and Arenig rocks adjoin, that is, in the lowest layers of the so-called ‘Garth Grit’. In 1913, when Prof. E. J. Garwood gave his Presidential Address on ‘Algæ as Rock-Builders’ to Section C at the Birmingham Meeting of the British Association, Prof. Fearnsides exhibited specimens of the nodular material which he had collected from the basal layers of the Garth Grit exposed in the cliff at the head of Cwm Bowydd, 100 yards south of the new hospital at Blaenau Ffestiniog, and from Bryn Glas. At that time, Prof. Fearnsides had recognized that the micro-structure of the nodules afforded evidence of their organic origin, and suggested that they had been built up by algal incrustation upon a grit or pebble base. As, however, biologists were unable to discern any real resemblance between micro-sections of the nodules and those of algae, no interpretation of their structure was at that time forthcoming.

Since the Birmingham B.A. Meeting, quarrymen, endeavouring to exploit an unproved vein of slate at Bryn Glas, west of Llyn Morwynion, have opened further chambers in the
Naos pagoda
(Salter), the Type of a New Genus of Silurian Corals.
Authors: Lang William Dickson
Published: October 2009

I.—In 1873, J. W. Salter described a new species of Rugose Coral as follows:— ‘The genus [Ptychophyllum] is not confined to Britain. An Arctic form from the northern expeditions is in the cabinet o the Geol. Survey. In this the successive growths of the calyx are so regular and the limb turned so much back, that the whole resembles a Chinese pagoda, whence the name Ptychophyllum pagoda Salter.’

Salter's description and the specimens which he has described appear to have remained unnoticed. R. S. Bassler has overlooked the species in his ‘Bibliographic Index of American Ordovician & Silurian Fossils’; nor can I find any reference to it in other literature. There are, however, in the British Museum (Natural History) three specimens of the G. H. Morton collection, labelled ‘
Ptychophyllum pagoda
, Salter, Niagara Group, Melville Island’ (Brit. Mus. R 4805-806, R 25163), and three specimens clearly of the same species (Brit. Mus. R 4983, R 25165-66), labelled ‘? Niagara Group, ? Disaster Bay, Arctic America’. It is nearly certain that the last were handed over by the Geological Survey to the British Museum in 1880, with other fossils from Arctic America, and that they are Salter's syntypes. It is desirable, therefore, that Salter's
Ptychophyllum pagoda
should be figured and described in detail. The specimens are silicified, and externally coated with beekite. Internally, the structure is beautifully preserved, and shows relationship both with
Chonophyllum
and
Ptychophyllum
.

Diagnosis.—Simple Rugose corals with the outer part of the calice reflexed, and differing from
Ptychophyllum
in
The Geology of the Country between Drygarn and Abergwesyn, (Breconshire)
Authors: Davies Kenneth Arthur
Published: October 2009

The region with which this paper deals lies in the north-western corner of Breconshire, and is situated some 5 miles north of Llanwrtyd Wells, the nearest place of note. The area surveyed is one bordered on the south-west by the rivers G-wesyn and Culant, both tributaries of the Irfon, and stretches roughly 4 miles to the north of this line; its western boundary is marked by the Irfon—Towy watershed. Abergwesyn, a small village, stands at the junction of the Irfon and the G-wesyn.

The district comprises part of the plateau of Central Wales, and is drained by the Towy and tributaries of the Wye, of which the Irfon, roughly bisecting the area, is the most important. The Irfon and its two main tributaries, the Gwesyn and the Cammarch, cut through the rocks generally at right angles to the strike, so that the streams (at least on the south side, where the valleys are deeply incised) afford good sections through the greater part of the succession.

The country on the north, however, closes in to form a desolate moorland at a height of about 1600 feet, rising to 2115 feet in Drygarn, a prominent mountain-top which can be seen from most parts of Central Wales. This northern region is thickly covered with peat, so that the rock-exposures are much fewer and of by no means so satisfactory a character as on the southern side of the area.

The district has, apparently, never been described in detail, and there are no difinite
The Geology of North-East Land (Spitsbergen)
Authors: Sandford Kenneth Stuart
Published: October 2009

This paper is the result of exploration carried out in 1924 by the Oxford University Arctic Expedition, and observations are also included which were made by Mr. C. S. Elton with the Merton College Expedition of 1923.

North-East Land is about 100 miles long from east to west, and some 80 miles from north to south. That it is so little known is due to its peculiar position remote from the Gulf Stream, which keeps the western coast of the main island of Spitsbergen remarkably clear of ice-pack. On the other hand, North-East Land is struck by the cold Polar current which brings large quantities of ice from the neighbourhood of Franz Josef Land. This current divides, to pass along both the northern and the southern coasts. These factors, together with almost incessant fog, combine to make North-East Land difficult of approach, except late in the season or in unusually favourable years. Moreover, unless an expedition is prepared to winter there, the time available for scientific research is extremely limited.

We owe our introduction to the geology of the northern coast to Baron A. E. NOrdenskiöld (1), who, in the spring of 1873, sledging along the sea-ice, made close observation of its structure (2). Landing near its eastern end he traversed the dome of ice to a point about half-way down the western coast, whence he skirted the shore back to Low Island and returned by water tp his base at Mossel Bay (see fig. 7, p. 632).

Among others
Jurassic Chronology: III—Some Faunal Horizons in Cornbrash
Authors: Buckman S. S.
Published: October 2009

This communication was commenced and mainly written several years ago: it was intended to form the concluding part of the paper on Watton Cliff (III, 8) following after consideration of Fuller's Earth, Great Oolite, etc., strata. But that paper grew to a length which rendered necessary exclusion of studies of strata later than Inferior Oolite. Now lack of time makes further partition necessary, so that the Cornbrash portion is taken by itself.

The Cornbrash has usually been described as a comparatively thin band of limestone-rock stretching continuously across England from the coast of Dorset to the coast of Yorkshire, parting the Oxford Clay above from Forest Marble Clay below. It is implied in such description that the Cornbrash is a synchronous deposit, which took a short time to form, and that it contains a comparatively homogeneous fauna.

Is such a view correct, or is the continuity of the Cornbrash deceptive? Is not this band of limestone made up of various heterochronous deposits and how far is its fauna homogeneous?

Many years ago, my father noticed the phenomena which form a basis of the present studies—the distribution of dissimilar faunas —in regard to the brachiopods of the Cornbrash. In 1853, speaking on the subject at the Meeting of the British Association for the Advancement of Science (II, 2) he remarks: ‘The author expressed his opinion that certain oolitic Terebratulæ (viz.
T. digona, obovata, lagenalis, ornithocephala
) should be considered as forming one species, at the same time admitting that these forms characterized
The Nature and Origin of Soil-Polygons in Spitsbergen
Authors: Elton Charles S.
Published: October 2009

The observations recorded in this paper are largely the result of work carried out during the summer of 1924, the bulk of which was done on Reindeer Peninsula, Liefde Bay, in Northern Spitsbergen, and, unless otherwise stated, the notes refer to that place. I wish to acknowledge my indebtedness to Mr. George Binney, the leader of the Oxford University Arctic Expedition, for giving me every facility that lay in his power, and to Dr. K. S. Sandford, geologist to the expedition, who has allowed me to use some of his observations, and whose advice has been of great value. I also wish to thank Mr. R. C. Spiller for examining and giving me his opinion on some soil-samples; Mr. O. W. Richards for certain useful notes on polygons; and Mr. D. Kempson for the care with which he has made prints of some of the photographs.

While investigating the factors which affect the distribution and succession of Arctic animals and plant-communities I was brought up against certain problems of surface-geology, and found it necessary to solve these before progress could be made with the other work. The most important of these problems was presented by the various polygonal arrangements of the soil, which are known to be peculiar to Arctic and Alpine regions, and have now been shown to play a definite part in the processes of weathering and disintegration of rock in such regions. Further, by affecting the nature and drainage-conditions of the soil, they have very marked effects
On Old Red Sandstone Plants showing Structure, from Brecon, South Wales
Authors: Heard Albert
Published: October 2009

The plants that are described in this communication represent the first recorded occurrence of well-preserved early Devonian plants in England and Wales.

The fossil locality was first observed by Mr. F. N. Gossling, B.A., of the Post Office Survey Department, who informed Prof. A. H. Cox of the occurrence. Prof. Cox and I subsequently examined the locality, and collected a large number of specimens, and I am greatly indebted to Prof. Cox for handing over to me the investigation of the fossil plants. The quarry from which the fossil plants were collected is situate on the western side of the road between Merthyr and Brecon, and lies 7½ miles south of Brecon. (See fig. 1, p. 196.)

The plant-remains are entombed in sage-green arenaceous shales, which are intercalated among the typical sage-green sandstones of the Senni Beds of this locality. The fossil plants appear to be confined to the sediments of finer grain.

Some of the plants in this Brecon assemblage of early Devonian types assume an increased importance, on account of their perfect mode of preservation, which enables a more or less complete account of the anatomy of the vegetative organs to be furnished.

The plants exhibit great diversity in their mode of preservation. At first sight, most of the fossils appear to consist of carbonaceous material. A closer investigation, however, reveals the fact that in many cases a carbonaceous film merely covers the interior of the stem, which has been subject to varying degrees of pyritization.

In some
The Geology of Snowdon, North Wales
Authors: Williams Howel
Published: October 2009

I. Introduction.

The area to be described is limited on the north-east by the Pass of Llanberis from near the village of Nant Peris to Pen-y-gwrhyd; on the south-east by the Vale of Gwynant down to Beddgelert; on the south-west by the Colwyn and Gwyrfai valleys to near the village of Salem; and on the north-west by the supposed line of junction between the Cambrian and the Ordovician rocks. The approximately quadrilateral area of Ordovician rocks thus defined has an extent of about 30 square miles. It is represented on portions of the 1-inch Ordnance Survey maps 106 & 119, of the 6-inch sheet, Caernarvonshire 22, and of the Quarter-sheets 16 S.E., 17 S.W., 21 N.E. & S.E., 27 N.E., & 28 N.W. It includes parts of the Quarter-sheets 75 N.E. & 78 S.E. of the 1-inch Geological Survey map (old series).

The general configuration of Snowdon is represented on the map, PL. XXIX. Prof. W. M. Davis's paper on ‘Glacial Erosion in North Wales’ [42] affords a useful guide to the topography, and is considered adequate for the present purpose.

(a) Historical Review.

On his first visit to North Wales in 1831, Sedgwick drew a section through Snowdon, in which he depicted the synclinal structure of the summit and the descending sequence of beds towards the north-west. From this section and from others across Y Glyder Fawr and Moel Hebog, he ascertained the general parallelism of the fold-axes in this part of Caernarvonshire. Subsequently, he determined the general succession
On some Mammalian Remains from Lake Nyasa
Authors: Hopwood Arthur Tindell
Published: October 2009

Though the kindness of Dr. F. Dixey I have been privileged to examine a number of fragments brought back by him from the Chiwondo Beds of Uraha Hill, Lake Nyasa. They are very much broken up, and only three pieces are in sufficiently good condition to allow of a generic name being applied to them. Nevertheless, they are of great interest, since they are the first vertebrate remains to be obtained from that region, and since they indicate a fresh means of throwing light on the problems connected with the Great Rift-Valley.

The bones are highly mineralized, of a greyish colour, and are badly cracked and fissured. Some at least of the cracking was effected before burial, but much of it is due to subsequent weathering. The matrix is a coarse quartzose grit with a calcareous cement. It is very hard, with numerous pockets of soft unconsolidated matter. in this respect it resembles the deposits of the Albert Nyanza and of the Victoria Nyanza. The Albert Nyanza deposits are cemented by oxides of iron, and are dark brown or black; but the fossils collected by Dr. Felix Oswald in the neighbourhood of Lake Victoria are, so far as the state of preservation is concerned, hardly to be distinguished from those collected by Dr. Dixey.

This does not prove that the beds near Lakes Nyasa and Victoria are of the same age. It is most unwise to rely on lithology as a means of correlation, especially when dealing with lacustrine deposits.
A Critical Revision of the Rugose Corals described by W. Lonsdale in Murchison's ‘Silurian System’
Authors: Lang William Dickson , Smith Stanley
Published: October 2009

W. Lonsdale, in R. I. Murchison's ‘Silurian System’, 1839, pp. 675–94, pis. xv, xv
bis
, xvi, & xvi
bis
, described and figured a number of Silurian corals and polyzoa. In view of the prominence of this work in the literature of Palæozoic corals and polyzoa, and the importance to nomenclature of a right interpretation of many of Lonsdale's figured forms, it is desirable that whenever possible the types and figured specimens should be re-examined and their internal structure carefully investigated.

It should be noted that our paper deals solely with the Rugose corals. The genotypes of several genera are involved, as well as the types of a number of species. Many of Lonsdale's forms have been misinterpreted by later authors, and placed by them in the synonymies of totally different coral-species.

Our paper has issued as a by-product of a work of wider scope begun in 1923—namely, an investigation of all the genera to which Palæozoic corals have been referred, with a view to determining their genotypes; it is also auxiliary to our impending publication dealing with the Silurian corals described in Linnæus's ‘Corallia Baltica’ and with the genera and species involved in a consideration of these. It aims at identifying unmistakably Lonsdale's Rugose coral-species, describing in detail those which do not come within the scope of our other work, and only very briefly considering such as will be fully described in that work. It has, however, been found desirable to consider also several of McCoy's types, as well as
The Geology of the Country between Llanelidan and Bryneglwys
Authors: Blackie Robert Churchill
Published: October 2009

The district here described lies partly in southern Denbighshire and partly in north-eastern Merionethshire. It covers an area of about twenty square miles, and includes the upper part of the Vale of Clwyd, and the upland region on the south of it. The parishes of Derwen, Grwyddelwern, Llanelidan, a large part of Bryneglwys and part of Llansantfraid-Grlyn-Dyfrdwy are included in the area. A close geological and geographical relationship exists between the present district and the main mass of the Denbighshire Moors on the north-west. The region consists of a more or less flat-topped upland which has been dissected by numerous valleys. The average height of the land is 1000 feet, but to north, west, and south it descends below 600 feet O.D.

Towards the east the area is connected by a ridge extending from Moel Traan to Mynydd-Cricor, averaging 1000 feet in height. The district here described thus forms a more or less rectangular tract of relatively high land surrounded on three sides by low-lying valleys.

The grain of the country runs from south-west to north-east, and is thus of Caledonian trend. A system of parallel valleys, most of which carry streams, separates the ridges. Less well-marked valleys also cut the upland in a west to east direction, intersecting the former at angles of about 60°. Where the two valley-systems meet, rather flat and swampy ground is usual.

On the north the uplands descend steeply to the upper part of the Vale of the Clwyd. The river Clywd follows this
The Old Red Sandstone of the Bristol District
Authors: Wallis Frederick Stretton
Published: October 2009

The object of this investigation was to study the Old Red Sandstone of the Bristol district from the stratigraphical, palæontological, and petrographical aspects, with the view of elucidating the source of the sediments, their mode of transportation, and the conditions of deposition.

To this end, a British Association Research Committee was appointed at the Edinburgh (1921) meeting. To Dr. H. Bolton, Chairman of this Committee, I am indebted for the suggestion of this research and for the opportunity of carrying it out under the auspices of the Bristol Museum.

Interim reports were presented at the Annual Meetings of the Association from 1922 to 1925, and the final report was submitted in 1926.

The areas of Old Red Sandstone involved in the folded and faulted ‘Bristol Uplift’ were taken as the limits of the investigation (map, p. 762). They comprise:—

a.

Outcrops within the ridge of Avonian rocks stretching from Penpole Point through Westbury to Durdham Down.

b.

The area stretching from the River Avon (left bank) to the neighbourhood of Clapton-in-Gordano.

c.

A coastal ridge between Portishead and Clevedon.

wing to the almost complete absence of organic remains, the Old Red Sandstone has received little attention from local geologists, and records of sections are framed in very general terms.

In 1846 D. Williams gave a detailed account of the Old Red Sandstone sequence on the right bank of the Avon Gorge as it was then visible some twenty years before