Limestone Bands Research Articles

The fossiliferous rocks of the Borrowstounness Coal-field

I. Lower Rocks. The lower marine (the so-called ‶mountain″) limestone usually taken as the inferior limit of the Scottish Carboniferous Limestone series is nowhere very distinctly seen on the Linlithgowshire coast, but the numerous blocks scattered about on the beach may be taken as an indication that its outcrop is about a mile and a quarter to the west of Blackness Castle, under the drift which at that place prevents the rock from being seen.* The thin argillaceous limestone or ‶cementstone″ which crops on the foreshore a short distance farther east, appears to be totally unfossiliferous, and has no resemblance to the great encrinal limestone of Charleston on the opposite shore of the Firth. The neighbouring rocks are chiefly shales and thin calcareous sandstones with fragmentary plant remains such as calamite stems, leaves, and scales of Lepidodendron, &c. The shales often contain beds of clay ironstone nodules, in some of which are to be found marine shells associated with small pieces of Calamites and other land plants. Orthoceras undatum (Flem.) is the only fossil which it has been my fortune to find in these nodules in a perfect state. The next rocks in the ascending series are sandstones, with ferruginous limestone bands and beds of shale. Immediately below the tuff at Carriden is a bed of black shale on which rests a coal seam a few inches in thickness. It is in turn overlaid by a bed of hard sandstone whose surface is covered with beautiful sharply-cut impressions of Spirophyton

Excursion to the Island of Inchkeith. 2nd July 1881

The party, numbering about thirty, left Leith in the tug ‶Fiery Cross″ for Inchkeith. The tide was at its lowest, and this enabled the party, who were led by Mr John Henderson, to survey all the strata on the shore under high-water mark. Around the northern end and a portion of the easterly side of the island, the beds are as well displayed as if pictured and sectioned on a geological map. Some new roads made in connection with the fortifications cut the strata diagonally, exposing fine sections by which the observations around the coast can be checked. Five-sixths or more of the island are great sheets of igneous rocks, between which are thinner bands of sedimentary deposits, including shales, two thin seams of coal, some highly calcareous shales, and bands of limestone. Many of the shales contain large numbers of fossil ostracodes and minute phyllopods, amongst which an Estheria (?) is abundant. A scale of Megalichthys was obtained, the first, it was understood found on the island. A prehistoric kitchen-midden was crossed on one of the new roads. When the rocks had been surveyed in situ, Mr Henderson gave an outline sketch of the leading divisions of the Carboniferous formation as developed in the counties bordering both sides of the Forth. Going somewhat into detail on the rocks comprising Inchkeith, he explained the character of the several strata, and said their geological horizon was near the top of the Calciferous Sandstone series. Observations had been directed to the junctions

III.—Note on two Palæozoic Crustaceans from Nova Scotia

The specimen referred to in the following note is I believe the first example of a Macrourous Crustacean from the Carboniferous of Nova Scotia; and it is interesting to find, as pointed out to me by Mr. Woodward, that its affinities are so close with the long known Palœocarabus dubius of Prestwich, and Anthra-palœmon of Salter, from the English and Scottish Coal-measures. It was found by Mr. Albert G. Hill, manager of the Cumberland Coal-mine, at the South Joggins in Nova Scotia, in one of the bands of black bituminous limestone which occur in the middle part of the Coal Formation.

The British Association

REPORTS.Third Report on the Sub-Wealden Exploration.—Mr. W. Topley made a statement on this subject, embodying the chief points of the report drawn up by Mr. H. Willett and himself. Up to the year 1872 nothing was known as to the beds which lie below the Wealden strata in the south-east of England. The lowest beds exposed were those on the north and north-west of Battle, long worked for limestone. The age of these beds was doubtful, some geologists correlating them with the Purbecks of Dorsetshire, others regarding them as Wealden but of somewhat exceptional character. In 1872, when the Association met at Brighton, Mr. H. Willett proposed to commence a bore hole in these doubtful strata, with a twofold object: (1) to determine the order, thickness, and character of the Secondary rocks below the Weald; (2) to prove the Palæozoic rocks which were supposed to lie beneath at a depth which could be reached. Judging from what is known of the Secondary strata near Boulogne, and comparing them with those exposed in the middle of England, it was hoped that the Palæozoic rocks would be reached at a depth not greater than 1,700 feet from the surface. In August 1874 the boring had reached a depth of 1,030 feet, and was then delayed in consequence of an accident to the rods. This hole was ultimately abandoned, and a new boring was commenced in February 1875, which has been carried to a depth of 1,812 feet. At this point the work has been stopped, in consequence of great difficulties in keeping the hole clear, and it is not proposed to continue the boring further. From the surface down to 175 feet the strata are shales and impure limestones, with gypsum in the lower part. These beds are referred to Purbecks, and with them are now classed the lowest rocks exposed at the surface, formerly called the “Ashburnham Beds.” From 175 to 257 feet the strata are chiefly sand and sandstones; these are held to represent the Portland Beds. Below 257 feet there is a great series of bituminous shales and clays, with occasional bands of cement stone and sandstone. Kimmeridge Clay fossils extend down to 1,656 feet at least, possibly lower; so that this formation is here at least 1,400 feet thick. The bottom beds of the boring, just reached, are oolitic in structure, and contain bands of hard limestone. To this extent, then, the Secondary rocks have been traversed, and their order and structure ascertained. A discovery of some commercial value has been made, for two companies are in existence to work the gypsum. One of these has been for some time in operation; a shaft has been sunk and the mineral is now being raised. Scarcely less important is the knowledge now attained that no supply of water can be got by deep wells or borings into the Sub-Wealden strata. As regards the Palaeozoic rocks, the boring has not had the success that was anticipated. The Secondary strata have proved too thick, and there is little or no hope of reaching the older rocks here._ A boring is now in progress at Cross Ness by the Metropolitan Board of Works; this will be carried through the gault, and may possibly throw some light on this question.

Notes on a Railway-section of the Lower Lias and Rhætics between Stratford-on-Avon and Fenny Compton, on the Occurrence of the Rhætics near Kineton, and the Insect-beds near Knowle, in Warwickshire, and on the Recent Discovery of the Rhætics near Leicester

A short distance from the Railway Station at Stratford-on-Avon, on the branch line to Fenny Compton, the red marl (new red sandstone) appears with overlying Keuper sandstone, capped by the usual drift. The Lower Lias comes in a little further on, where the strata are much disturbed and are thrown up in the form of a small anticlinal, and are displaced for a short distance on each side of the axis of disturbance, but are horizontal on the opposite of the cutting. Near the station at Eatington the Lima- and other beds are exposed in a cutting about sixty feet deep, consisting of the usual series of bands of limestone divided by shales here undisturbed, the lowest strata cropping out to the west with a dip to the east. They contain the usual characteristic fossils, though these are not very numerous. About a mile and a half from the station, in an easterly direction, the Rhætic (Penarth) beds make their first appearance, and are here composed of whitish shale, twenty feet thick, with irregular included nodules of limestone with Estheria , overlain by the White Lias much shattered and broken, which has evidently been redeposited with some intermixture of drift. At Walton Hill the black shales are seen underlying the “Estheria-bed;” but only a small portion is exposed, and the thickness is unknown; but possibly the “bone-bed” might be found lower down in the river Dene below.

On the Coalfield of Brora, Sutherlandshire

On the Coalfield of Brora, Sutherlandshire

On some Bivalve Entomostraca, chiefly Cypridinidæ, of the Carboniferous Formations

On some Bivalve Entomostraca, chiefly Cypridinidæ, of the Carboniferous Formations

On the Origin of Clay-Ironstone

A. 1. C lay-ironstone * is an impure carbonate of iron, containing generally from 30 to 33 per cent. of metallic iron mingled with varying proportions of clay, oxide of manganese, lime, and magnesia. 2. When the principal foreign matter in this mineral is of a bituminous or combustible nature the variety thus formed is called “Black band”†. This combustible matter often amounts to 25 or 30 per cent. 3. Sometimes lime so far predominates in Clay-ironstone as to give it the general appearance of a compact limestone, when the presence of iron may be detected by the great weight of the mass, and by the decomposition of the exterior, which turns a dark brown to the depth of a quarter of an inch or more on oxidation. 4. Through the intermediate forms it passes into a pure limestone. Such limestone bands are characterized by being densely compact, very hard, dark-coloured, and by being devoid of organic remains. B. 1. The foregoing varieties occur throughout the vast thickness of delta-deposits whose remains now constitute the Carboniferous formations. They lie in beds varying in thickness from a fraction of an inch to about 2 feet. 2. When the top of a bed is exposed it is often found to be traversed by a series of cracks, which present the general appearance of a net of very unequal and irregular mesh. These cracks are filled with sediment like that in which the bed of Clay-ironstone lies. 3. Very frequently the beds of all varietes

On the Lower Silurian rocks in the neighbourhood of Galashiels

I. Introductory. The Lower Silurian rocks of Scotland, largely developed as they are in the south, and in spite of the great labour that has been bestowed upon them, are by far the least known of all the fossiliferous formations of this country. While the maps of the Government Geological Survey are coloured in all the subdivisions of the strata of the other formations included in the area, the Lower Silurians are merely indicated by a common purple tint, and not the slightest attempt at a subdivision is made. Even the single bed of limestone they contain below the horizon of that of the west coast is doubtfully referred to the Llandeilo, and the sign of interrogation is carefully placed before its title. Nicol, Harkness, J. C. Moore, and many other eminent geologists, have worked different portions of these ancient deposits since the publication of ‶The Silurial System,″ but as yet very little progress has really been made in correlating its different parts with those of the type formation of the sister country. Now this want of accurate information is due to two causes: 1 st, The strata are so rapidly folded and contorted, and are consequently so intricate and confused, while at the same time they present so few differences lithologically, that anything like a physical separation of its masses is well-nigh impossible; and, 2 d, The whole formation, if we except of a few isolated bands of limestone towards the west, and some bands of anthracitic shale that make their

Zoophyta

This class is represented by a considerable number of genera and species, some of which are so abundant in certain horizons that their stony skeletons now form whole bands of limestone. Corals, being truly marine in their habitat, are never found in the strata of our upper coal measures, nor in the brackish or fresh-water beds that alternate with the limestone series or lower coal measures. They are always associated with fossils which represent true oceanic conditions, like the marine fauna of our present seas. About twenty genera and treble that number of species have already been recorded as found in our strata; and, as the work of investigation goes on, it is likely that other forms will yet be detected. The greatest number is found in the lower limestone series, some of which seem to be characteristic of this division, such as Lithodendron, Lithostrotion, Syringopora, Cyathophyllum, Amplexus, Heterophyllia, Michelinia, etc. Several of the genera have, however, a wider vertical range, being found in the lower, as well as in the upper limestones and shales. These are chiefly Clisiophyllum, Zaphrentis, Stenopora, and Alveolites; but corals, so far as I have observed, seem to be nowhere very abundant in the upper limestone series. Many of the Scottish carboniferous corals, being embedded in soft clay shale and calcareous shale, have their internal structure better preserved than specimens obtained from hard limestone, which are often so much crystallized internally that their finer septa are in many cases entirely obliterated. The localities of easiest This 250-word extract was created in the absence of an abstract

XVIII. Notes on the Section of Strata in the Gilmorehill Quarry, and Boulder-Clay, on the site of the New University Buildings, Glasgow

During the working of the sandstone in the western portion of the Gilmorehill grounds, for the purpose of obtaining stone for the New University Buildings, an interesting section of carboniferous strata has been exposed, which belongs to that division of our coal measures lying between the upper and the lower limestone series found to the north and west of Glasgow. Throughout the district this group of rocks is best known as the Possil and Govan ironstone series, from the valuable bands of that ore which it contains. But the equivalents of the group are also to be found in other tracts of our western Scottish coalfield, as at Kilsyth, Wilsontown, Carluke, and Lesmahagow, to the north-east, east, and south-east, and in the west at Johnstone and Dalry. The group of strata in which the Gilmorehill beds are placed, ranges from about 440 fathoms under the upper red sandstone of the Lanarkshire coalfield, down to the horizon of the Govan ironstone, which is stated to lie about 588 fathoms under the above-mentioned red sandstone. This series of rocks, nearly 900 feet in thickness, is therefore in the position of the middle division of the carboniferous limestone system of this and other countries, yet in the Glasgow district it contains very few persistent bands of limestone or other calcareous strata. The mineralogical aspect of the group is so much alike to that of our upper coal measures, that I have no doubt but that they were deposited under somewhat similar conditions. The This 250-word extract was created in the absence of an abstract

On New Specimens of Eozoon

S ince the subject of Laurentian fossils was placed before this Society in the papers of Dr. Dawson, Dr. Carpenter, Dr. T. Sterry Hunt, and myself in 1865, additional specimens of Eozoon have been obtained during the explorations of the Geological Survey of Canada. These, as in the case of the specimens first discovered, have been submitted to the examination of Dr. Dawson; and it will be observed, from his remarks contained in the paper which is to follow, that one of them has afforded further, and what appears to him conclusive, evidence of their organic character. The specimens and remarks have been submitted to Dr. Carpenter, who coincides with Dr. Dawson; and the object of what I have to say in connexion with these new specimens is merely to point out the localities in which they have been procured. The most important of these specimens was met with last summer by Mr. G. H. Vennor, one of the assistants on the Canadian Geological Survey, in the township of Tudor and county of Hastings, Canada West, about forty-five miles inland from the north shore of Lake Ontario, west of Kingston. It occurred on the surface of a layer, inches thick, or dark-grey micaceous limestone or calc-schist, near the middle of a great zone of similar rock, which is interstratified with beds of yellowish-brown sandstone, grey close-grained siliceous limestone, white coarsely granular limestone, and bands of dark-bluish compact limestone and black pyritiferous slates, to the whole of which Mr. Vennor gives a

On the Lias Outliers at Knowle and Wootton Warwen in South Warwickshire, and on the Presence of the Lias or Rhætic Bone-bed at Copt Heath, its furthest Northern Extension hitherto recognized in that County

T he Liassic outlier at Copt Heath, near Knowle, eleven miles south-east of Birmingham, has been referred to in the ‘Geological Transactions’ by my lamented friend, the late Hugh E. Strickland, and it was first noticed by my friend Dr. Lloyd; but it does not appear that any particular account has been given either of the one near Knowle or of the others in the neighbourhood of Wootton Warwen, which are, however, of sufficient interest to deserve a more detailed report. The outlier at Knowle is of limited extent, being about a mile and a half in length and half a mile broad. It occurs in the midst of the Red Marl, by which it is surrounded on all sides. A few bands of limestone are seen cropping out on the side of the canal; but the main mass is quarried by a shaft, so that the order of succession is not very easy to be traced; and as the works did not pay, they have been again closed, though a quantity of stone was raised in 1857. Judging from the blocks of stone and shale still remaining, they seem to represent the Saurian beds; and the presence of beautifully preserved specimens of Ammonites planorbis confirms this. Some of the masses of limestone are of large size, and contain remains of Saurians, scales of Fish, Ostrea, Modiola, Cardium , and a few other shells; the black laminated shales yield, besides the A. planorbis , a small Pecten and plates of a Cidaris . It

On the Mode of Formation of Limestone Bands

The existence of layers of limestone at various intervals among the rocks, while in the intermediate strata there is a remarkable deficiency of that substance, is a fact which I have not seen hitherto satisfactorily accounted for, but of which we may hope to find some rational explanation.

On Canadian Caverns

In the foregoing account it has been my aim and endeavour to describe the geological formations in which the caverns existed; this will be seen at a glance in the following table:—Taking the two classes together as representing thirty distinct series of cavernous localities, one is found in the New Red Sandstone formation, two in the Carboniferous, two in the Devonian or Old Red, seven in the limestones of the Upper, two in those of the Middle, and six in those of the Lower Silurian formation, three in the Huronian rocks of Sir William Logan, and seven in the Laurentian rocks of the same geologist. In the last of these they are present in the interstratified bands of crystalline limestone, characteristic of this formation in Canada.

On some Cretaceous Rocks in the South-Eastern Portion of Jamaica

B elow the thick Tertiary deposits in Jamaica are found thin beds of fossiliferous limestone, underlaid by igneous rocks. These strata form the subject of the following communication. The newest bed of the fossiliferous limestones is exposed on the north side of the Plantain-garden River, three miles west of Bath. This section shows a bed of compact limestone, 8 feet thick, resting on a thick bed of conglomerate, and overlaid by shale. The shale is of a dark colour and without organic remains. The limestone is compact and grey, with thin veins of calc-spar; it contains numerous fossils, all of them characteristic of Cretaceous or other Secondary strata, viz. Inoceramus, Hippurites , and Nerinœa . The conglomerate is composed of rounded pebbles of igneous rocks and a white fossiliferous limestone; it is succeeded by a great thickness of unfossiliferous black shale. A quarter of a mile higher up the river there is a section of some vertical beds of limestone, probably older than the series already described. A bed of conglomerate separates them from great masses of porphyry. This section (see woodcut) exhibits thin bands of limestone, alternating with shale, containing limestone-nodules. Some of the thin bands of limestone are crowded with fossils, principally Inoceramus, Hippurites , and a species of Bulla (?). These fossilfferous beds are succeeded by a bed of conglomerate, 12 yards thick, composed entirely of pebbles of porphyry, identical in structure and colour with the adjacent mass. The conglomerate is not altered at its junction with the igneous rock. The

On a Section of a part of the Fifeshire Coast

This section of the Carboniferous strata, as exposed on the northern shore of the Firth of Forth, from Anstruther to Burntisland, represents the strata, at about high-water mark, arranged as occupying the space due to their real thickness only. The Carboniferous rocks in this section present three great natural groups:—1, the Lower Carboniferous; 2, the Mountain-limestone; and 3, the Upper Carboniferous, or the workable coal-measures. From Anstruther, on the cast, to beyond Pittenweem the sequence of strata is clear, exhibiting a magnificent series of the Lower Carboniferous rocks (approximately 3800 feet thick), consisting of freshwater or estuarine shales and sandstones, with a few bands of limestone, one of which latter is of marine origin. The comparative abundance of Sphenopteris affinis characterizes the upper portion of this inferior group; and of Cyclopteris , its lower portion. The Burdiehouse limestone belongs to the upper portion; and, like the other calcareous bands, gets thinner eastwardly. The Granton beds, on the contrary, appear to belong to the lower portion. The lowest portion of this Lower Carboniferous series has Cyclopteris , Stigmaria , Carpolithes , and Cypridœ . The marine band—an argillaceous limestone, in the middle of the series—has Encrinites , Fenestella , Nucula tumida , N. attenuata , and Productus semirecticulatus . The upper half of the series contains Sphenopteris affinis , Cypridœ in abudance, and Palœoniscus . The strata have a westward inclination, with a gradually increasing angle of dip, which is still greater towards St. Monance, as the section traverses the “Mountain-limestone” series. This consists of sandstones and shales, with five or six beds

On the Vertical and Meridional Lamination of the Primary Rocks

Abstract The author described wide regions in several parts of the world as exhibiting in their geological structure the phænomena of successive vertical bands of schistose and crystalline rocks, parallel with each other, and having a meridional strike. This structural condition was illustrated by several extensive and highly finished sections, some of them traversing several hundred miles, made from the author's own observation in Panama, South America, Australia, and Ceylon. The section across the Andes, for instance, exhibited parallel bands of quartzites, porphyry, mica-schists, greenstone, granite, gneiss, hornblende schists, trachyte, crystalline limestone, talcose schists, and clay-slates, occurring in variable succession, with a N. and S. strike, and with an almost uniform vertical dip. In plains and other places where the laminated structure has not been disturbed by local causes, the cleavage planes were shown to be more or less vertical; but sometimes in high ridges with precipitous flanks the bands and laminæ of rocks drop on both sides, from want of lateral support, thus giving the appearance of a radial or fanshaped structure. Here and there on the edges of these laminated rocks rest horizontal sedimentary deposits; and it was pointed out that many of these exhibited at the point of contact with the older rocks evidence of their undergoing the process of vertical cleavage or lamination ; the lines of stratification becoming gradually obliterated. Even compact mud and soil lying on the edges of the schistose rocks have been observed by the author to be subject (under certain conditions) to cleavage and interlamination with calcareous and siliceous matter. Mr. E. Hopkins maintained that in all parts of the world the old crystalline or “primary” rocks exhibit (with local exceptions, insignificant when compared with the whole) a uniform vertical cleavage or foliation, with a north and south direction ; and that the rocks in those countries, like Australia, part of India, Siberia, South America, Central America, and California, which preserve this meridional uniformity, are productive of gold, platina, silver, and precious stones on the decomposed edges of the schists ; whilst those regions which have been disturbed or bent from their normal position are more or less productive in masses of the ordinary minerals, and are comparatively barren of the precious products. In speaking of the meridional structure, Mr. Hopkins alludes to the N.E. variation of the cleavageplanes in the northern hemisphere, more especially in the United States and Europe; but, nevertheless, he believes that the general uniformity approximates more nearly to the true meridian than the magnetic meridian does. The author observed also that, from his acquaintance during numerous mining operations with the deep-seated rock-masses of the Andes and elsewhere, he was convinced that the great base below was more or less granitic strongly saturated with mineral waters, and that it passed upwards by insensible gradations from a crystalline heterogeneous compound to a laminated rock (as gneiss), and still higher up to schists in vertical planes ; the peculiar varieties of the higher rocks being dependent on the mineral character of the “parent rock” below; the schistose rocks forming, in short, the external terminations of the great universal crystalline base. Mr. E. Hopkins referred to some important remarks on parallel lamination of nearly vertical rocks and on cleavage, made indeendently by Humboldt*, M'Culloch† Sedgwick‡, and De la Beche§ and, leaving for further consideration the question as to how the lamination and cleavage of rocks were brought about, he concluded by recommending the study of the primary rocks, with their various transitions and foliations, to the special notice of geologists, as being of extreme interest, and likely to throw great light on several important points in geological science.

On the Southern Border of the Highlands of Scotland

Having lately visited many of the passes leading into the Highlands, I found the arrangement of the rocks along the border so different from what I had been led to expect by what has been published on the subject, that I venture to offer the following remarks upon the Border formations, although I am far from having materials for a complete account of them. Mr. Nicol's ‘Guide to the Geology of Scotland’ gives us a good summary of what was known on the subject up to 1844, and little or nothing has been added since; his account, therefore, will often be referred to. In MacCulloch's Map of Scotland a band of blue colour, indicating “Clay-slate or Greywacke,” stretches across Scotland from Stonehaven to Bute and Arran, bounded on the south by the Old Red Sandstone, and on the north by mica schist, and within this clay-slate are represented the bands of limestone of Loch Lomond and Aberfoyle. Mr. Nicol's map includes in the same band of clay-slate the limestones of Callander and that on the South Esk near Cortachie. Mr. Buist's Map of Perthshire, published in the forty-fifth number of the Journal of the Highland Society, draws into the same Clay-slate Formation the limestone between Dunkeld and Blair Gowrie.

Sketch of the Structure of parts of North and South Wales

Summary The fossil evidences here cited indicate— 1. That the sandstones skirting the Longmynds are the upper beds of the Caradoc. 2. That they were deposited under peculiar local conditions. 3. That they were deposited around the margin of land. 4. That in all probability they were deep-sea deposits around high and steep land. 5. That the land was of Llandeilo flags or older rocks. 6. That they are in sequence with the limestone bands at the base of the Wenlocks. 7. That part of the Meifod fossiliferous beds are in a lower parallel, and probably Middle Caradoc.