bluuebunny/crossref_metadata_2025 huggingface dataset:
On Perlitic Felsites, probably of Archæan Age, from the Flanks of the Herefordshire Beacon; and on the possible Origin of some Epidosites
Authors: Rutley Frank
Published: October 2009

In a previous communication to this Society a rock was described (No. 20) in which faint indications of a perlitic structure were discernihle. It occurred on the side of the Herefordshire Beacon, overlooking Castle-Morton Common, and a short distance in rear of the well-known cave.

The specimens now under consideration were derived from the Rabbit Warren near the above-mentioned locality; No. 1 from a point about thirty yards above the path, where it touches a small beck which runs between the higher portion of the Beacon and the Warren ; while No. 2 was procured a little above and to the east of this spot, and about halfway up the steep bank of the Warren.

The first is a rather deep greenish-grey to brownish-grey rock, which, on a smoothly-cut surface, shows a meshwork of very delicate veins, darker than the material of which the rock is mainly composed.

The second specimen is of paler colour, a yellowish-green or buff tint predominating.

It was difllcult at the time to procure better samples, and both of these must be regarded as in a considerably advanced stage of alteration. They were, however, kept, as they seemed to show faint indications of perlitic structure, and although, in sections cut from them, the structure is somewhat obscure, there is nevertheless sufficient proof that it is present.

A section taken from specimen No. 1 appears by reflected light, under a low power, to consist of greenish-white to greyish-white matter, broken by small dark specks and curved
On a Hornblende-biotite Rock from Dusky Sound, New Zealand
Authors: Hutton F. W.
Published: October 2009

This rock was collected in Dusky Sound by Mr. W. Docherty, and given to the late Sir J. von Haast, who gave it to me. I do not know its field relations, but undoubtedly it is of eruptive origin and is associated with the Archœan gneisses and schists of that district. As I am not aware of any similar rock having been described, I think that some account of it may be interesting.

The rock is compact, crystalline, of a dark green colour, weathering reddish brown, and the specific gravity varies between 3·00 and 3·07. With a lens it is seen to be composed of two minerals in nearly equal proportions. One is a black mica, the plates of which are sometimes collected into masses 0·1 to 0·2 inch in diameter, but generally scattered through the other mineral. Cleavage-flakes of this mica can be easily detached, and, under the polariscope, prove to be biotite, in which the two optic axes nearly coincide. When thin, these cleavage-laminæ have a greenish tinge by transmitted light

Under the microscope, in thin sections of the rock, the biotite has the usual brown colour and strong dichroism. It often contains crystals of apatite, which is, I think, not usual.

The other mineral, in thin sections, is of a pale bluish-green colour and dichroic, but not strongly so, passing from a pale brownish green to a pale bluish green, some portions being more strongly dichroic than others. With ordinary light very little structure is apparent, but
On the Eozoic and Palæozoic Rocks of the Atlantic Coast of Canada, in Comparison with those of Western Europe and of the Interior of America
Authors: Dawson J. William
Published: October 2009

Since the year 1845 the author has contributed from time to time to the Journal of this Society more than forty papers on the geology of Nova Scotia, New Brunswick, and Prince Edward Island, in which frequent comparisons were made between the rocks and fossils of the Atlantic coast-region and those of the inland plateau of the North-American continent on the one hand, and those of Europe on the other. Many additional details bearing on the more uncertain parts of these subjects have been accumulated in unpublished notes in recent years, while large additions to our information have resulted from the extension of the Geological Survey of Canada, under Logan and Selwyn and their assistants, to those provinces, and from the Geological Survey of Newfoundland under Murray and Howley, while new facts have been accumulating with reference to the continuation of the Atlantic rocks southward on the coast of the United States, and also with regard to the intermediate or “inner marginal” series observed on the Lower St. Lawrence and thence southward. The time seems thus to have arrived when some further and useful comparisons may be made, as well as corrections and amplifications of previous statements; and these seem to be the more necessary, inasmuch as it is evidently difficult for geologists who have not personally studied these districts to correlate with accuracy the geological features of the marginal belts of the two sides of the Atlantic.

The subject is, however, so extensive that within the limits of this
Second Note on the Movement of Scree-Material
Authors: Davison Charles
Published: October 2009

The first results of the experiment described in this note, namely, those relating to the period from May 5 to September 22, 1887, have already been recorded in a paper read before the Geological Society on February 29, 1888.

After a brief interval the experiment was continued under the same conditions as before, from October 4, 1887, to May 5, 1888, with the object of comparing the rates of descent in the winter and summer halves of the year, and also of determining the effects on creeping of rain and snow.

Allowing a
distance of ½ mm. for the interval of 12 days during which the experiment was suspended, the total descent during
the year was 13⅙ mm. (
i. e.
a little more than half an inch), the mean rate of descent being therefore ·00140 inch per day.

Comparison of the Rates of Descent during the Winter and Summer Months
.—Dividing the year of the experiment into winter, from October 4, 1887, to April 3, 1888, and summer, from May 5 to October 4, 1887, and April 3 to May 5, 1888, we have :—

Had the creeping movement been proportional to the range of temperature, the average daily descent during the winter, compared with that during the summer, would have been rather less, namely ·00095 inch per day. Not only, however, is the heat of the sun more intense in summer than in winter, and consequently the effects produced by passing clouds
Directions of Ice-flow in the North of Ireland, as determined by the Observations of the Geological Survey
Authors: Kilroe J. R.
Published: October 2009

The field observations of the Geological Survey, Ireland, being completed, it was considered desirable by the Director to represent those bearing on glacial phenomena in the northern half of the country on a general map, scale ten miles to one inch. Data for this were amply furnished by the one-inch sheets already published, and by those in course of preparation, upon which the usual map-indications of glacial striæ are numerous and distinctly shown. These indications consist of circles denoting the places of observation, lines crossing those circles giving the trends of striæ, and arrowheads attached thereto indicating the directions of ice-fiow when these are determinable.

In carrying out this transfer a remarkable circumstance became apparent, namely, that the striæ were capable of being resolved into two distinct sets, nearly at right angles to each other; which rendered it convenient to appropriate two copies of the general map to the two sets of striæ. The striæ thus transferred have been further connected by continuous lines about three eighths of an inch apart, or have served as guides when the lines do not happen to pass through the exact points of observation. So constant in direction are the striæ of each set over an area of some 16,000 square miles, that they maintain an almost unswerving parallelism to those continuous, though slightly waved lines. Comparatively few deviate more than a few degrees to one side or the other of the general direction, such deviation being adequately accounted for by local inequalities of
On Fulgurites from Monte Viso
Authors: Rutley Frank
Published: October 2009

The specimens described in this paper were collected within six or seven feet of the summit of Monte Viso (about 12,680 feet above the sea-level) by Mr. James Eccles, F.G.S., who kindly forwarded them to me for examination.

The larger one, fig. 1, Pl. III., is a piece of compact bluish-grey rock, about 6½ inches long by 1¾ inch in its greatest breadth. In one part it shows a delicate banding, the direction of which is indicated by an arrow,
b
, placed on the left of the figure. This banding, however, is not distinctly visible on the surface represented, although it is well defined on the back of the specimen, which is bounded on one side by a smooth joint-plane,
c c
, upon portions of which a thin crust of fulgurite-glass has been formed. The outer surfaces are far less even; but if not actually joint-planes, they have, at all events, been directions of easy fission, suggestive of a system of intersecting joints, and these, in several parts, are incrusted with minute pellets and thin films of fulgurite-glass.

The surface shown in fig. 1, Pl. III. (natural size), has been ploughed out by lightning, the track being marked by curved and branching, hemicylindrical furrows,
a a
, varying from about
1/2
inch to
1/32
inch in diameter.

These tubes are lined with a thin crust of dark brown, vesicular fulgurite-glass, and one of the smallest branches of the longest tube is completely filled with this substance. The approximate thickness of
Notes on two Traverses of the Crystalline Rocks of the Alps
Authors: Bonney T. G.
Published: October 2009

Introduction

In the address which I delivered at the Anniversary Meeting of the Society in 1886, I gave a brief outline of some investigations into the petrology and structure of certain districts of the Oberland, Pennine, and Lepontine Alps. These had led me to conclusions which were then stated, and had further indicated to me the principal types of rock recognized by the Swiss geologists, and enabled me, as it were, to translate into stone one of their maps. I then determined to make two traverses of the Alpine chain at distances remote from the central portion (the scene of my previous work) and from each other, so as to acquire a knowledge of the rock-types employed in mapping by geologist outside the Swiss Republic, and compare the crystalline schists or gneisses of these regions with those already known to me. The points, I may again mention, on which I was specially seeking for light were (1) the relation of foliation to pressure, stratification, &c., or, in other words, the history of the genesis of gneisses and schists; (2) the value of the apparent stratigraphical succession which I had observed over a considerable district of the Swiss Alps.

For these purposes it was rerquisite that any section examined should fulfill, as nearly as possible, the following conditions:—

(1)

It should run in a fairly straight line as nearly as might be at right angles to the apparent strike of the rocks.

(2)

It should exhibit a seeming succession as extensive as possible.
On the Jersey Brick-Clay
Authors: Dunlop Andrew
Published: October 2009

A fine yellow clay which occurs in Jersey and in at least some of the other Channel Islands has received little attention from geologists, and the few who have noticed it appear to have considered it merely the result of local weathering. This clay is more or less sandy, and though generally of a dull yellow colour, is sometimes reddish orange. On microscopic examination many of the grains are seen to be somewhat rounded, but the majority of them have sharp angles. In one or two situations the clay effervesces freely with acids, and at some places on the coast it has been found to coat the grass roots with a pipe-like covering. On a small detached island on the south-east coast it contains fantastically-shaped concretions like the “
Mannchen
” of the Rhenish löss. This, however, is probably due to the fact that above the clay at this point there is a bed of shells, all modern, from which carbonate of lime has been washed down by rain. Sometimes the clay exhibits obscure marks of bedding, and at one point in the town of St. Helier, where an excavation had been made for relaying some drains, I noticed distinct lamination. Mr. Green, a well-sinker, has also told me that, in sinking wells, he has often noticed distinct stratification. The lower part of the clay often contains angular stones, sometimes grouped together pretty closely, sometimes at some distance from each other, while occasionally a single stone, or one or two, may be
On some Nodular Felstones of the Lleyn
Authors: Raisin Catherine A.
Published: October 2009

I
n
the descriptions which have been given of various igneous rocks from the Lleyn, no details have, I believe, been published of the two small outcrops near Pwllheli, to which this paper refers. Some specimens, which I collected in 1885, I showed to Professor Bonney, and, at his suggestion, I tried to make a more thorough examination of the rocks. The two masses rise, like small islands, from the drift-covered plain around, and project seawards in the headlands of Pen-y-chain and Careg-y-defaid. They are marked on the Survey map as consisting of intrusive felspar porphyry with agate nodules. I propose, first, to describe the general types of rock, and, secondly, to notice certain structures, especially those connected with the nodules.

I. G
eneral
S
uccession
A
nd
A
ge
O
f
T
he
R
ocks
.

At Pen-y-chain the rocks show distinct evidence of stratification, and the beds seem, on the whole, to dip about N.N.E., although with irregularities, such as might be expected in volcanic masses. Thus the lowest strata which I reached were the rocks near the south or south-westerly point. They form the seaward part of the cliff, against which the long beach from Pwllheli terminates. The rock is darkly veined, with subangular fragments of whitish felstone, which shows faint indications of fluidal structure and contains porphyritic felspar and quartz. This rhyolitic rock seems to have undergone a brecciation
in situ
; for some of the neighbouring fragments were evidently once continuous, and the blackish veins fade off at places and are lost in the felstone.
Notes on the Geology of Madagascar
Authors: Baron R.
Published: October 2009

G
eneral
D
escription

M
adagascar
is as yet almost a
terra incognita
to the geologist, nothing, so far as I am aware, but notices of the most fragmentary kind ever having appeared in regard to its geological features; and, indeed, until the country is surveyed by competent men, we must be content with descriptions of the most general character. In the absence of something more complete, I present the following notes, drawn up from personal observation, to which I have added here and there few remarks taken from other sources, as a slight contribution to our knowledge of the geology of this great island.

The central portion Madagascar is generally regarded as consisting chiefly of granite. Mr. Wallace, for instance, in his ‘Island Life’ (p. 384), says of it: “ A lofty granitic plateau, from 80 to 160 miles wide, and from 3000 to 5000 feet high, occupies its central portion, on which rise peaks and domes of basalt and granite to a height of nearly 9000 feet;” and in the same book there is a physical sketchmap in which the whole of the interior of the island, from about 14° to 23° S. lat., is represented as an “elevated granitic region.” Now if we use the terms “granite” and “granitic” in a wide and popular sense, and include in them the various members of the crystalline series of rocks, the description may be regarded as correct; for by far the greater part of the eastern half of Madagascar consists of gneiss
On the Dentition of
Lepidotus maximus
, Wagner, as illustrated by Specimens from the Kimeridge Clay of Shotover Hill, near Oxford
Authors: Etheridge Robert , Willett Henry
Published: October 2009

The specimens upon which this paper is founded were obtained by one of us (Mr. Henry Willett) from the Kimeridge Clay of Shotover Hill, and at no great distance from each other, although at different times—two in the spring and one in the autumn of 1887, and the fourth in the spring 1888. The size and perfection of these specimens are alone sufficient to warrant their being brought under the notice of the Society; but, besides this, one of them appears to represent a distinct species, probably new to England, if not also to the Kimeridgian fauna of France.

The species of
Lepidotus
known in England are as follows:—

Section L
eptoganoidei

Suborder L
epdosteoidei

The Lepidosteoid Fishes range from the Permian to the present day. They are represented in the Permian rocks by the genus
Acentrophorus
. The following genera range through the British Secondary rocks:c

Many species of
Lepidotus
attain a large size.
Lepidotus maximus
, Wagn. (=
Sphœrodus gigas
, Ag.), from the Lithographic Stone of Solenhofen in Bavaria, measures over 5 feet in length and 2 feet in depth of body; while
L. Mantelli
, Ag., from the Wealden Series (Hastings Sand) is nearly, if not quite, of equal dimensions.

The similarity of the teeth in
Sphœrodus
and in the larger species of
Lepidotus
(such as
L. maximus
) induced Agassiz to abolish the latter genus (but with hesitation) in 1869. Prof. Owen, however, from the microscopic structure of the teeth, regarded the two genera as distinct. On the other hand, many continental palæontologists
On the Production of Secondary Minerals at Shear-zones in the Crystalline Rocks of the Malvern Hills
Authors: Callaway Charles
Published: October 2009

In an introductory paper
*
read before this Society in April 1887, I gave a rough sketch of the mode in which certain of the Malvern schists
†
were produced ; but no attempt was made to offer a complete solution of the questions discussed. At the British Association in 1887 and 1888, and at the International Geological Congress in 1888, I briefly stated certain additional results, reserving particulars of the evidence for more detailed communications. One of the most important branches of the inquiry is the genesis of the respective minerals, especially of the micas. If, as I hope to prove, some of the most abundant minerals are of secondary origin, the ground will be cleared for working out the details of the problem in hand.

Minute particulars of rock-composition will rarely be necessary in this paper. The principal varieties of the Malvern rocks have lately been carefully described by Mr. Rutley
‡
, and, furthermore, I believe that the question is to be settled rather by field-evidence than by the study of minute structure. Indeed, the chief results were decided in the mind of the writer before a single slide had been cut. Nevertheless more than 150 rock-sections have been prepared. Some typical examples of these were submitted to the skilled examination of Dr. H. B. Patton, assistant to Prof. Rosenbusch, of Heidelberg, and he has generously permitted me to incorporate his notes in this communication
§
. My thanks are also duen to Mr. J. J. H. Teall for several valuable suggestions, and his admirable monograph
*
has been of much use. It is satisfactory to note that Mr. Teall has recognized
†
at the Lizard certain "banded gneisses" to which he assigns an origin similar to that of the "injection-schists" of my last paper ; but I understand that he expresses no decision on the genesis of the granite-veins. Prof. Bonney has also favoured me with his opinion on certain points.
Cystechinus crassus
, a new Species from the Radiolarian Marls of Barbados, and the Evidence it affords as to the Age and Origin of those Deposits
Authors: Gregory J. W.
Published: October 2009

The most important addition made by the ‘Challenger’ to our knowledge of the living Echinoidea was unquestionably the discovery of those abyssal Spatangoids which are Ethmophract, Meridosternous, and Adete; it was the close resemblance of these to the Cretaceous Ananchytidæ that led to the well-known and oftrefuted generalization that we are still living in the age of the Chalk. The discovery of a new species of
Cystechinus
, one of the most typical of these genera, in the Radiolarian beds of Barbados is therefore of interest; and this is enhanced by the light it throws on the age and horizon of those well-known deposits.

Of the genus
Cystechinus
Prof. A. Agassiz has only given a comparative diagnosis; in the original description he simply states that it has the general appearance of
Ananchytes
, the simple ambulacral system of the Pourtalesiadæ, and an actinostome less labiate than in that group. He points out that it serves, with the genera
Homolampus
and
Palæotropus
, as a transition from the Spatangidæ to the Nucleolidæ and Echinolampidæ.

In the ‘Challenger’ Report this notice has been somewhat expanded. Here the Galeritic features of the subcentral actinostome and the position of the anal system, the Ananchytid apical disc, the simple pores, the rudimentary auricles, and the proportions of the coronal plates in the ambulacral and interambulacral areas are all noticed.
On a new Genus of Siliceous Sponges from the Lower Calcareous Grit of Yorkshire
Authors: Hinde George Jennings
Published: October 2009

Nearly forty years since, Dr. H. C. Sorby, F.R.S., communicated to this Society a paper on the microscopical structure of the Calcareous Grit of the Yorkshire coast, in which reference was made more particularly to the nature of certain microscopic reniform bodies with which the rock ill places was largely filled. In mineral constitution some of these bodies were of calcite, others of chalcedonic silica, whilst ill others both these minerals were present, and the question as to their original constitution was decided by Dr. Sorby in favour of the calcite, since it was thought extremely iml;robable that, if originally of silica, this material would have been dissolved and replaced by calcite, whereas the substitution of silica in place of calcite was a well-known phenomenon. The definite tbrm and outline of these bodies left no doubt that they were of organic origin, and Dr. Sorby recognized their resemblance to the small siliceous globules which form an outer crust to many existing sponges, but rejected this view on the ground of their supposed calcareous nature, trod he finally concluded that they were small shells, possibly Foraminiferal, in whose inteiior calcareous or siliceous materials had been infiltrated, in the same manner as in the chambers of the Ammonites occurring in the same rock.

Subsequently, in 1876, Prof. J. F. Blake, F.G.S., discovered similar minute bodies in rocks of nearly the same age in Dorsetshire and Wiltshire, and noticed that some of them were hollows enclosed by thin crusts or shells, which dissolved
The Propylites of the Western Isle of Scotland, and their Relation to the Andesites and Diorites of the District
Authors: Judd John W.
Published: October 2009

I. I
ntroduction
.

There exists in the Western Isles of Scotland a great series of lavas which, for the most part, underlie the ophitic olivine-basalts, and constitute the oldest of the ejections of the great Tertiary volcanoes of that district. These rocks were distinguished by me in 1874 under the old English field-name of “Felstones,” and it was stated that they “vary in colour from black, through various shades of green and grey to white; but in almost all cases their surfaces acquire a white crust in consequence of weathering action”

In attempting, at that date, to define more exactly the characters of these lavas, by studying them microscopically in thin sections, I was confronted by two difficulties. In the first place, it soon be became manifest that these more acid lavas of the Western Isles include a great variety of types--differing widely from one another in mineralogical constitution and in structure; and in the second place it was found that the minerals of which those rocks were built up were in a remarkably altered condition.

In both these respects, the “felstones” present a very striking contrast to the overlying series of ophitic olivine-basalts. The latter, as I have shown, are remarkable for their uniformity of composition and character, and, except where influenced by surface-agencies, seldom present any great signs of alteration; they are indeed, as a rule, singularly fresh and unchanged in their appearance.

But in the “felstones” which underlie the basalts the most extreme metamorphism is seen to have
The Devonian Rocks of South Devon
Authors: Ussher W. A. E.
Published: October 2009

§I. I
ntroduction

“ In South Devonshire the rocks are greatly disturbed, broken by faults, standing at various angles, folded, and distorted ; eruptive rocks frequently cut through them, and beds of volcanic ash are interstratified with them, Hence has arisen great dispute and uncertainty as to the true order of succession of deposits, although their fossils were referred to the Devonian age nearly fifty years ago. It will be seen without comment that the South Devonshire sections, from which most of the Middle- and Lower-Devonian fossils have been obtained, are valueless for determining the order of sequence of the faunas. There are many places (I saw such near Newton-Abbot) where limestones, appearing very similar in colour and structure, and within a stone's throw of each other, hold distinct faunas. In fact, the interpretation of the order of the beds is a matter of the greatest difficulty, even when occasional fossils appear.”

Here is the geology of South Devon as epitomized by Professor H. S. Williams, of Ithaca, N.Y., in a paper read before the American Association for the Advancement of Science as lately as Aug. 30, 1889. Explorations in the rocks of Devonshire gave rise to the Devonian System; explorations in France, Belgium, Germany, Russia, and North America have made us acquainted with the succession of the Devonian faunas, and the extraordinary persistence of homotaxcous horizons, such as those characterized by
Stringocephalus
,
Rhynchonella cuboides
, and
Goniatites
, at the same time presenting us with the varied evidences of stratigraphical succession.

The
On Burrows and Tracks of Invertebrate Animals in Palæozoic Rocks, and other Markings
Authors: Dawson J. William
Published: October 2009

§Introduction

The present paper is intended to contribute some recently acquired facts to the solution of questions connected with these often problematical markings; and it will consist rather of short notes, illustrated by photographs, than of a connected discussion of the subject. I propose to notice the nature of certain markings sometimes referred to plants, under the name of
Bilobites
, —to the true nature of the
Scolithus canadensis
of the Potsdam Sandstone,—to certain tubes similar to those of modern
Sabellæ
, —to cylindrical concretions resembling trunks of trees, —and to imitative markings, and peculiar trails of doubtful origin.

§ II. Bilobites, Rusichnites, Protichnites, and Climactichnites.

(Fig. 1 to 6.)

The name
Bilobites
, proposed by Dekay in 1823, was as Newberry has shown, originally applied not to objects of this kind, but to casts of certain bivalv shells. It was therefore dropped in America; but it has been revived and has gained currency in Europe†, as a term including various forms of markings referred to different genera. The dominant characters are a band, or an oval mass, with a median longitudinal furrow or ridge, and marked with transverse or oblique furrows or strim, and with or without a marginal ridge. The writer was enabled to show in 1864 that one of the most remarkable of these impressions, Rusophycus grenvillensis of Billings, and Gruziana-like markings associated with it, were really burrows and tracks of marine animals, probably Crustaceans. He arrived at this conclusion by a careful study of the impressions made by the recent
On some Water-worn and Pebble-worn Stones taken from the Apron of the Holt-Fleet Weir on the River Severn
Authors: Marten Henry John
Published: October 2009

In the year 1844 a weir was constructed by the Severn Commissioners across the River Severn at a place called Holt Fleet, about eight miles above the city of Worcester, with the object of impounding the water above it, for navigation purposes, to a height of 5 feet 4 inches above previous low summer-level.

The weir, a plan and section of which accompany this paper (figs. 7 & 8), is a dam of solid masonry across the river, without any sluices in it; so that the whole of the water passing down the river at that point flows over the crest of the weir and down the slope, or face of the apron, on its lower side.

The crest of the weir is 300 feet in length, and the drainage from 1870 square miles (nearly 1,200,000 acres) of country above it, extending to the Plinlimmon range, is discharged over it.

The stones of which the weir is constructed were taken from an adjoining quarry at Holt Fleet, and consist of a soft red sandstone of the Upper New-Red-Sandstone Formation, marked F. 5 on the one-inch map of the Geological Ordnance Survey.

In the year 1887, or 43 years after the stones were placed on the apron of the weir, an examination was made of them, as some of the stones had become displaced and others showed signs of decay.

The examination brought to light the fact that a large proportion of the stones on the Island side of the central
On the Physical Geology of Tennessee and Adjoining Districts in the United States of America
Authors: Hull Edward
Published: October 2009

P
art
I.—§ 1. I
ntroduction
.

A
recent
visit to the Southern States of North America induces me to lay before the Society some observations on the physical aspect of a peculiarly interesting region traversed by the Tennessee River in the State of the same name and the bordering districts. The geological structure of this district has been ably described by Professor James M. Safford, the State Geologist. The region is now in process of being re-surveyed topographically and geologically under the direction of Major Powell, U.S. Geological Survey, to whom I am much indebted for kind assistance in procuring maps and information. In the present communication I do not propose to enter at any length into the geological structure of the district here described, but only to single out the most striking features connected with its physical structure, and to endeavour to show how they can be accounted for upon those principles of interpretation which, after many years of discussion and research, are generally adopted amongst geologists. Amongst others we shall have to explain the formation of table-lands, and of the erosion of the gorge by which a great river, the Tennessee, traverses a mountain-plateau in pursuing its way towards the ocean, instead of taking a much more direct course.

§ 2. P
hysical
F
eatures
.

1.
The Valley of East Tennessee
.—The physical features of East Tennessee are, when viewed on a large scale, extremely simple, and are a faithful index to the geological structure. Along its eastern margin, where Tennessee joins North
On the Unconformities between the Rock-systems underlying the Cambrian Quartzite in Shropshire
Authors: Callaway Ch.
Published: October 2009

I
ntroduction

A
bout
twelve years ago I devoted some attention to the Archæan rocks of Shropshire, and a commnnication on the subject appeared in the Quarterly Journal (1879, vol. xxxv. p. 643). Additional results were published in the numbers for May, 1882 (vol. xxxviii. p. 119), and November, 1886 (vol. xlii. p. 481). Some details, however, remained for settlement. Of these the most important is the relation between the great volcanic system (Uriconian) and the vast series of sediments which takes its name from the Longmynd. Ten years' additional experience amongst the Archæan rocks has given me some advantage in reviewing my old evidence, and recent criticisms by Prof. Blake call for some notice.

The following is a summary of my published conclusions, with Prof. Blake's objections:—

i.

The volcanic rocks (Uriconian) of the Wrekin and Caer Caradoc are older than the Longmyndian. Prof. Blake admits that they are older than the upper part of the Longmyndian, but contends that they are not older than the lower part of that series. He accordingly separates the Longmyndian into an upper member (Cambrian) and a lower member (Monian). He furthermore expresses the belief that in one locality (Pontesbury) the felsites regarded by me as pre-Longmyndian are really intrusive in rocks which he considers Cambrian.

ii.

The granitic and gneissic rocks (Malvernian) of the Wrekin and other Salopian localities are older than the Uriconian, since they furnish rounded fragments to Uriconian conglomerates. Prof. Blake, on the other hand, holds
On the Age, Formation, and Successive Drift-Stages of the Valley of the Darent ; with Remarks on the Palæolithic Implements of the District, and on the Origin of its Chalk Escarpment
Authors: Prestwich Joseph
Published: October 2009

§1. G
eneral
C
haracter
and
A
ge
of the D
arent
V
alley
.

I
n
former papers t I have touched incidentally upon the drift phenomena of this district, and on the occurrence of a peculiar group of flint implements found on the adjacent Chalk plateau. I now purpose to limit my observations to the circumscribed valley of the Darent, which I have had more special opportunities of studying since my residence at Shoreham.

This valley, including the district surrounding it, is of peculiar interest, from the circumstance that its geological history, beginning with pre-Glacial times, may, with few breaks, be traced to Neolithic times; as also from the light it throws upon the age of some of the Thames-Valley drifts, and from its distinctive groups of Palæolithic implements. It is moreover free from the complication produced in the valleys north of the Thames by the presence of foreign-drift elements, for here the drift is restricted to débris derived from its own drainage-area.

The Darent Valley is one of the few which run through the Chalk escarpment into the so-called Wealden area §, though it does not pass beyond the first outworks, being shut out by the range of the Lower Greensand from the central Weald. To the south of the Chalk range, the valley branches westward in the line of the main stream to near Limpsfield, and eastward to near Ightham in directions parallel with the ranges of the Lower Greensand aud the Chalk, and is terminated by watersheds which separate it in the
On Nepheline Rocks in Brazil.—Part II. The Tingua Mass
Authors: Derby Orville A.
Published: October 2009

In a former paper under the above general title (Quart. Journ. Geol. Soc. vol. xliii. 1887, pp. 457
et seq
.), the distribution, so far as it is at present known, of the nepheline-bearing rocks in Brazil was given, together with a somewhat detailed description of the Pocos de Caldas locality. Since that time three important petrographical papers relating to this group of rocks have appeared, one of which is accompanied by a detailed geological description of the insular, and presumably later, eruptive mass of Fernando de Noronha.

In this and subsequent papers, it is proposed to treat of the other continental localities, with special reference to the geological relations and mode of occurrence of this interesting group. One of the localities enumerated in that paper—the Serra de Bocaina—should be eliminated from the list, as a recent examination shows it to be composed exclusively of gneiss and granite. The specimens reported to have come from this locality are probably from the neighbouring mass of the Serra de Itatiaia.

The peak of Tingua is one of the two prominent masses that break the somewhat monotonous, approximately even-topped out-line of the Serra do Mar, as seen from Rio de Janeiro; the other being the well-known Serra dos Orgões. Of the two, the former, although of less elevation (1600 as compared with 2232 metres), is, to the geological eye at least, the most striking, since its topographical features, and more particularly its conical form and apparent distinctness from the range to which it belongs,
The Tudor Specimen of
Eozoon
Authors: Gregory J. W.
Published: October 2009

The unanimity with which the view of the organic origin of
Eozoon canadense
was received on its announcement in 1865 by Sir William Logan, Dr.(afterwards Sir J. W.) Dawson, and Dr. W. JB. Carpenter, in the Quarterly Journal of this Society, was first seriously broken by the publication, in the succeeding volume, of the memoir by Professors King and Kowney “On the so-called Eozoonal Rock”. In the following year the Quarterly Journal contained a series of “Notes on Fossils recently obtained from the Laurentian Rocks of Canada, and on objections to the organic nature of
Eozoon
” by Dr. (afterwards Sir J. W.) Dawson, the most valuable contribution in which was the description of a specimen found by Mr. H. G. Vennor in a limestone belonging to the Hastings series at Tudor, Hastings county, Ontario. This was identified as
Eozoon canadense
, though as possibly a new variety, by Sir J. W. Dawson, who seemed to consider that this discovery relieved him of the necessity of making any detailed reply to the arguments of his critics, as “furnishing a conclusive answer to all those objections to the organic nature of
Eozoon
which have been founded on comparisons of its structures with the forms of fibrous, dendritic, or concretionary minerals—objections which, however plausible in the case of highly crystalline rocks, in which organic remains may be simulated by merely mineral appearances readily confounded with them, are wholly inapplicable to the present specimen ” §.

The importance of the new discovery depended on the
A Contribution to the Geology of the Southern Transvaal
Authors: Penning W. H.
Published: October 2009

I. I
ntroduction
.

(a)
The Southern Transvaal
.—The area occupied by the Witwatersrand beds offers many facilities for accurate observation. I have been enabled to collect sufficient evidence to fairly establish the relation between the geology of the district and that of the older known gold-fields, and thus to briefly describe the geology of the Southern Transvaal. The accompanying map (PI. Xu shows an area about 350 miles in length and 50 miles in breadth (or 17,500 square miles in extent). Some points require further elucidation ; but the geological features, as expressed on the map and sections, are generally correct according to my interpretation.

For a description of the district here referred to and its eastern border, see Quart. Journ. Geol. Soc. vol. xl. (1884) pp. 658
et seqq
., with map and sections.

The granitic rocks are most frequently fine-grained, and generally include little mica, but sometimes much hornblende. Whether pegmatite, syeni.te, or granitd, they are comparatively little exposed in the Southern Transvaal.

The granite (
a
, on map and sections) is frequently broken through by dykes of diorite, which almost always run nearly north and south. So also are the stratified rocks of all ages broken through in this way ; but the older these are the more numerous are the dykes within them. In the granite, the various minerals have sometimes been re-assorted by the effects of the dykes—layers of quartz and felsite, or of kaolin, flanking the dykes on both sides for considerable distances.

The general absence of fossils
The Cross Fell Inlier
Authors: Nicholson H. A. , Marr J. E.
Published: October 2009

§ I . I
troductory
.

S
ince
the “Description of an Insulated Group of Rocks of Slate and Greenstone in Cumberland and Westmoreland, on the East side of Appleby,” given by Dr. Buckland in the Transactions of the Geological Society (ser. 1, vol. iv. (1817) p. 105), a considerable number of papers have been devoted to the Lower Palmozoic rocks of that region, but as references to these are given in Mr. Whitaker's list of papers bearing upon the geology of the Lake District, published in the late Mr. Clifton Ward's memoir ou “The Geology of the Northern Part of the English Lake District,” it is needless to insert here an account of the bibliography of the area. An excellent summary of the work which has been achieved is given by Mr. X. G. Goodchild in a paper published in the Proceedings of the Geologists' Association for 1889. In this paper also considerable additions are made to our knowledge of the rocks of the Inlier, and to these we shall have occasion to refer.

In the present paper, we have attempted to fix the ages of the various formations of Lower Palmozoic rocks in the Cross Fell district, to determine their organic contents, and to compare them with the corresponding rocks of other areas, rather than to give a detailed description of the general structure of the region. This latter will no doubt be done by the officers of the Geological Survey who have been engaged in mapping the district, with far
The Inferior Oolite of the Cotteswold Hills, with special Reference to its Microscopical Structure
Authors: Wethered Edward
Published: October 2009

P
art
I.—T
he
G
eneral
S
tructure
.

(a)
Introduction

T
he
main divisions of the Inferior Oolite in the Cotteswold Hills are known to geologists who have made a study of Jurassic rocks, but to those who have not done so and to foreigners they may be less familiar. In order, therefore, that my remarks may be the more easily understood, I indicate the following main divisions which I propose to adopt, deferring my explanations of them till later on. They are given in descending order :—

Ragstones.

Upper Freestones.

Ragstones

Oolite Marl.

Lower Freestones.

Pea Grit.

Transition Beds, resting on the Upper Lias.

(b)
The Transition Beds
.

Position and General Structure
.—There has been considerable discussion among geologists as to where the line is to be drawn between the Inferior Oolite and the Upper Lias. To give even a summary of the controversy would take up considerable space and tend to divert the reader's attention from the primary object of this paper. I will, therefore, only mention the views of two geologists who may be said to represent the respective contentions. The late Dr. Wright, F.R.S., referring to the zone of
Harpoceras opalinum
, said : “This zone was formerly grouped with the Cephalopods-bed of Frocester ; but, as it contains some species which are limited to this horizon and are associates of
H. opalinum
, it is best to
On Wells in West Suffolk Boulder-clay
Authors: Hill Edwin
Published: October 2009

On taking up my residence in the heart of the Suffolk Boulder-clay, I at once began to enquire the depths of wells, in order to learn the thickness of its mass. The nature of the answers was unexpected. The depths at which water is obtained appeared altogether irregular and capricious ; ulitmately it seemed necessary to conclude that in some cases, possibly in many, the water is met with not below but in the interior of the Clay itself.

Here is an instance. A well in an outhouse of this Rectory (Cockfield, seven miles S.S.E. of Bury St. Edmund's) gives water at a depth of 35 feet. Another, outside its grounds, 120 yards W., obtained till this depth was reached. But another, the same distance N.N.W. of the first, is only some 8 or 10 feet in depth. Boulder-clay forms the subsoil to within a few inches of the surface, which in the case of each of these wells is about 300 feet above Ordnance datum.

Other wells have the following depths, the distances and directions being measured from the Rectory :—One half a mile N.N.E. (surface about 290 feet) 50 feet ; another a quarter of a mile N. (300 feet) 70 feet. In the opposite direction, at Cockfield New Hall, three quarters of a mile S.W. (255 feet), water was found at various depths down to 35 feet, but at the New Barn, a quarter of a mile farther S.W. (aboutt 280 feet), the depth was 126 feet.
On the Inverness Earthquakes of November 15 to December 14, 1890
Authors: Davison Charles
Published: October 2009

I. I
ntroduction
.

The earthquakes felt towards the close of last year in the district round Inverness form an interesting chapter in the recent physical history of Great Britain. Fortunately, the first undoubted shock was the most severe one, and this drew the attention of numerous observers to the slighter, but not less important, earthquakes which succeeded it. In some respects the evidence is incomplete, owing to the early house at which many of the shocks occurred ; but it is on the whole full enough to indicate in outline the succession of events and their relation to the geological structure of the district.

In studying these earthquakes the accounts given in the local newspapers have been found of some service, but I have chiefly relied on records sent to me in reply to a series of questions which were circulated as widely as possible throughout and near the disturbed area. At the end of this paper I have acknowledged in detail the help thus received ; but I wish here to offer my hearty thanks to those who have assisted me—first, for the valuable information which they have placed at my disposal, without which this paper could not have been attempted, but not less for the unfailing courtesy and kindness with which my enquiries have been received.

During the period mentioned at least eleven undoubted shocks were felt. Besides these, there were nine others, each depending on the evidence of one witness only, but they were noticed and recorded by
On
Dacrytherium ovinum
from the Isle of Wight and Quercy
Authors: Lydekker R.
Published: October 2009

As far back as 1857 Sir Richard Owen described and figured in this Society's Journal the nearly complete mandible of an Ungulate mammal from the Headon beds (Lower Oligocene) of the Isle of Wight under the name of
Dichobune ovina
. Subsequently it was pointed out by P. Gervais that this species could not belong to the genus
Dichobune
(or
Dichobunus
, as it should be called), but that it was closely allied to
Xiphoclon
. At a still later period I myself came to the conclusion that the so-called
Dichobune ovina
should be referred to the genus
Dacrytherium
, established by Dr. H. Filhol on specimens obtained from the Quercy Phosphorites of Central France, and I accordingly adopted for the name of the species
Dacrytherium ovinum
.

With regard to the French specimens on which the genus and species
Dacrytherium Cayluxi
were established by Dr. Filhol,it may be observed that the most important are a cranium and a mandible, which were said to be associated. These specimens were subsequently described in the ‘Ann. Sci. Geol.’ vol. viii. (1877) pp. 217
et seq
., the cranium being represented in pl. xviii. figs. 311–313, and the mandible in pl. x. figs. 254–256. It being assumed that the cranium and mandible were associated, neither was specially distinguished as the type, but since the name
Dacrytherium
was appropriately given from the presence of a large lachrymal fossa in the cranium, it is manifest that the latter must be regarded as the actual type of the genus and species.

In Referring
Supplementary Remarks on Glen Roy
Authors: Jamieson T. F.
Published: October 2009

In order to have a right conception of the manner in which the Glen Roy Lake originated it is necessary to have some knowledge of the state of matters that preceded it. During the Glacial period the ice upon the West side of Scotland seems to have been vastly thicker than it was on the East, owing no doubt to the snowfall having been much heavier in the former district, just as is now the case with the rainfall there. The amount of rain in the West Highlands is twice or three times what it is on the East coast. This is due not so much to the greater height of the hills as to the fact that the clouds of vapour coming from the Atlantic have most of their moisture condensed there. It is there that the wet sponge is first squeezed. The rain-gauge on the top of Ben Nevis has yielded no less than 145 inches of water in the course of a single year, whereas at Laggan, in the upper part of Strath Spey, the average is 46, and on the shores of the Moray Firth only from 25 to 30 inches. It is also important to observe that it is
during winter
that the greatest precipitation takes place. In some seasons as much falls on Ben Nevis in the month of December alone as there does near Inverness in the course of a whole year.

We shall probably not be war wrong in assuming that during