Northern Ireland geology

BGS Image no: P006468

Just E. of Ballintoy Harbour, Co. Antrim. Looking E. Upper Chalk and Tertiary dolerite intrusions just east of Ballintoy Harbour, Co. Antrim. Intrusive plug of Bendoo on right-hand side with chalk stack in centre. Sheep Island still in centre middle distance with Rathlin Island on horizon. View facing east from small cave 200 yd. south-east of Ballintoy Harbour.
Old photograph number:  NI00317

BGS Image ID: P224977

Port Reostin. Looking NE. Spaniard Rock and Chimney Tops. Five flows of dark-weathering Lower Basalts seen above sea level and below the Interbasaltic Bed which outcrop along the path. The overlying irregularly columnar lowest two flows of the Tholeiitic Basalts are seen to the right, the Chimney Tops being the columnar base of the second flow.
Date taken: 01/05/1959
Old photograph number:  NI00290

BGS Image ID: P225388

Irish Harp and Chimney Tops. Looking S. The footpath cut in the Interbasaltic Bed underlies the irregular columns of the first flow of the tholeiitic basalts. The isolated columns of the Chimney Tops are part of the second flow and a small part of the third flow is seen at the cliff top.
Date taken: 01/01/1969
Old photograph number:  NI00712

Posted by Bob McIntosh

Geologists' Association Field Excursion to Leith Hill June 3rd 1912

Geologists' Association Field Excursion to Leith Hill June 3rd 1912. Names of those listed:
C. Bromehead, Miss Cadmore, Miss Bassett, Miss Crosfield, A.C. Young, A Crosland (?), C. Candler (?). Dr. Bernstein, W. Watts, A. Gibbons. H. Lapworth.

From the Geologists' Association 'Carreck Archive' held at the British Geological Survey.

Posted by Bob McIntosh

Cartographic curiosity - Geological Survey of Scotland 1:10,560 Argyll Sheet 18

Geological Survey of Scotland 1:10,560 Argyll Sheet 18. 1878 [eastern half added c.1933]  The 'Clean Copy' deposited for public consultation. 

While searching the old Survey geological maps of the Beinn Mheadhoin/Strontian area for information about mineral workings, Don Cameron, a BGS geologist, came across this handwritten note which seemed to be scurrilously referring to Edward Battersby Bailey (E.B.B.) the then Director of the Geological Survey of Great Britain. Further investigation by Marcus Mulcahy of the BGS Enquiries Team in Edinburgh unearthed the original fieldslip with an admission in Bailey’s handwriting that he mapped the area in question, noting: 'I know this part may be very badly mapped. I did it myself before I knew anything at all about gneiss rocks.' This matches the writing on the 'Clean Copy' above, so its likely that Bailey made the admission before the map was copied! The field slip is shown below.

Original fieldslip: Geological Survey of Scotland 1:10,560 Argyll Sheet 18 NE by 'R.C.B.J.' i.e.   Robert Cyril Briscoe Jones with manuscript notes by  Edward Battersby Bailey.

Note on the maps: A geologist would survey the area by taking a set of Ordnance Survey maps cut up for convenience in the field. The geologist would walk over the ground drawing in the geology he sees and making notes on the field slips and collecting rock samples for identification. In the evening during field days he would 'ink in' the lines he had surveyed. Much later, back in the office a 'Clean Copy' of the map would be made with the final interpretation and deposited in the Survey Library for consultation, the map would also be used when compiling the various published maps. 

To learn about geological mapping in the early days of the Survey visit here. 

Today, the process of mapping is all digital.

Posted by Don Cameron, Marcus Mulcahy, Gill Nixon and Bob McIntosh

Nodule tools, Kent's Cavern, Torquay.

BGS Image ID: P232125

Photographs of nodule tools (breccia) from Kent's Cavern, Torquay. Photographs taken by A.R. Hunt. Photographs are from the British Association for the Advancement of Science photograph collection.

BGS Image ID: P232126

BGS Image ID: P232127

BGS Image ID: P232128

BGS Image ID: P641048

BGS Image ID: P641049

Posted by Bob McIntosh

Black Moss, Dinnet, Aberdeenshire. Kieselguhr or diatomite works 1917

BGS Image ID: P000025

Black Moss, 2.4 km. north of Dinnet Station. Aberdeenshire. 1917. The kieselguhr (diatomite) works. Extracting the kieselguhr. Kieselguhr overlain by peat marking site of silted-up lake. The vertical trenches show the method of draining the peat. Before silting-up, the shallow lakes had an abundant supply of nutrients and silica from the surrounding granites. Conditions were ideal for the prolific growth of lacustrine diatoms and the formation of fairly pure diatomite. Subsequent climate change and lowering lake levels lead to the formation of the overlying peat.

BGS Image ID: P000028

Processing the kieselguhr (diatomite). Drying in open-sided covered sheds. A close-up of the second process in the method of drying the kieselguhr. The cut blocks are clearly seen in rows of low open sheds. On the left blocks are placed on an uncovered low wooden structure with the blocks of the first drying process on the ground behind.

BGS IMage ID: P000031

Inside the large kieselguhr (diatomite) storage sheds. The photograph shows the method of building and piling the dried kieselguhr blocks within the sheds. The blocks are arranged in a herringbone fashion. Two bicycles are propped against the blocks.

BGS Image ID:  P527719

A specimen of diatomite from the deposit at Muir of Dinnet near Ballater, Aberdeenshire. Diatomite is a fine-grained earth substance resembling chalk or white clay in appearance and when dry easily breaking down into a white powder. Some specimens are as light as cork and can absorb four times their weight of water. It is composed of frustules of diatoms, extremely minute siliceous organisms. British Geological Survey Petrology Collection sample number MC 7496. In about 1880 a substance referred to as 'white moss' was reported underneath the peat at Muir of Dinnet. It was recognized as a diatomaceous deposit by the Rev. George Davidson and was regarded as a substance that could replace kieselguhr in the manufacture of dynamite. Practically the whole commercial output was sent to the Ardeer explosive works in Ayrshire where the organic matter was burnt away in kilns before use as an absorbent for nitro-glycerine in the manufacture of dynamite.

Posted by Bob McIntosh

Plates from James Sowerby's British Mineralogy 1802-1817

BGS Image ID: P704650

PLUMBUM Galaena. Sulphure of Lead; Galena. Plate no. 24. From: Sowerby, James. 1802-1817. British Mineralogy: Or Coloured figures intended to elucidate the mineralogy of Great Britain. Plate from vol: 1. page no.55. Modern name: Galena. Location: Collected found in Derbyshire.

BGS Image ID:  P705138

FERRUM carbonatum. Carbonate of Iron in rhomboidal spiculae. Plate no. 512. From: Sowerby, James. 1802-1817. British Mineralogy: Or Coloured figures intended to elucidate the mineralogy of Great Britain. Plate from vol: 5. page no.209. Location: Highgate Tunnel.

BGS Image ID: P704728

SILEX Quartzum, crystallisation. Crystallized Quartz; Cairn Gorum Crystals. Plate no. 102. From: Sowerby, James. 1802-1817. British Mineralogy: Or Coloured figures intended to elucidate the mineralogy of Great Britain. Plate from vol: 2. page no.1. Modern name: Smokey quartz (var. Cairngorm).

Posted by Bob McIntosh

Marbles from the Walter Brown Collection

BGS Image ID: P576068

P576068
Marble specimen. Calabria, Italy. Pallizzi Quarries, Calabria, Italy.
Calabria, Italy. Alternative name: Agrillei. Specimen description: Red/brown, orange and white fragments-veins. Anselm Odling. 

Text from: Watson, J. British and foreign marbles and other ornamental stones. Cambridge : University Press, 1916:

317 AGRILLEI. Pallizzi Quarries, Calabria. This specimen is an example of the dark variety of Calabresian Marble. It is composed of reddish brown and orange-coloured brecciated fragments, in a greyish brown matrix.

BGS Image ID: P576086

Marble specimen. Emperor Red, Portugal. Pedra Furada Quarries, Pero Pinheiro, Estremadura.

Emperor Red, Portugal. Alternative name: Encarnado. Specimen description: Red with pink/white markings and small fossil fragments. 

Text from: Watson, J. British and foreign marbles and other ornamental stones. Cambridge : University Press, 1916:

388 ENCARNADO (Emperor's Red). Pedra Furada Quarries, Pero Pinheiro, Estremadura. This is a red marble varied with streaks of dale pink and white, and faint outlines of small fossils may also be seen. In the British Isles this variety of Portuguese Marble is known commercially as Emperor's Red. It is not only in constant demand in Lisbon and other cities of Portugal for decorative purposes, but it is freely exported to England and other countries for similar work. Good examples of its use may be seen in St Roque's Church, Lisbon, and in the Municipal Hall, the internal decorations of both buildings being largely composed of it.

Emperor's Red is frequently used for ecclesiastical work in England. It appears in the Opus Alexandrinum pavement in the chancel of Bristol Cathedral (1895), and there are other examples in the chancel pavement of Truro Cathedral (1886), and in that of Peterborough (1895). It may be seen in many of the public buildings and hotels in London; for instance, in the Norfolk Hotel, and in the Drapers' Hall, built in 1898, where the handrails of the staircase and some of the door casings are composed of it.
It may interest the Cambridge student to hear that it was intended by Sir Gilbert Scott, the architect of St John's College Chapel, that the Communion-table slab in the chapel should be composed of Portuguese Emperor's Red Marble. It is stated that Sir Gilbert arranged with a marble merchant for the supply, but it was found afterwards that a block of Belgian Rouge Royal Marble (see No. 158 Watson J. British and foreign marbles. 1916.) had been furnished instead.

BGS Image ID: P576016

Marble specimen. Yellow Brocatelle, Spain. Tortosa Quarries, Prov. Tarragona, Spain.
Label name: Yellow Brocatelle, Spain. Alternative name: Tortosa Brocatello. Specimen description: Deep Red; containing yellow, white and transparent fossil fragments. Also known as / Brocatelle d'Espagne. 

Text from: Watson, J. British and foreign marbles and other ornamental stones. Cambridge : University Press, 1916:

421 TORTOSA BROCATELLO. Tortosa Quarries, Prov. Tarragona. This large slab is a typical example of a class of marbles known in Spain as Brocatello, a term applied with slightly different meanings in Spain, France, and Italy. Spanish Brocatello, known usually as Tortosa Brocatello, and sometimes distinguished as Brocatelle d'Espagne, resembles a mottled marble in general appearance, but on closer inspection, it is found to be made up of a red ground, in which there are a multitude of fossils. Many of the shells are crushed, and are so closely packed as to form the body of the marble, a characteristic which causes it to be included in the group of marbles known as Lumachella, a name given to an ancient marble sometimes found in excavations at Rome, chiefly made up of small shells. The groundmass is deep red, but as the numerous fossils vary in colour from yellow to snow white, and are sometimes replaced by colourless transparent calcite, the marble, generally, has a light appearance.

The quarries are situated near Tortosa, a town in the Province of Tarragona. They were worked vigorously in ancient times, and the marble was then known as Marmor Schiston. During the Roman occupation large quantities were sent to Rome. It may be seen in the Church of St Maria Maggiore in that city, there being an example at the side entrance of the chapel. The high altar of St Cecilia is also partly composed of it. The altar of the Transept Chapel of the Church of St Paolo fuori le Mura has colonnettes of Tortosa Brocatello. There are numerous examples of its use in Naples, where columns of it may be seen in the Chapel of St Januarius. It is now chiefly used in Spain for small panels, mantelpieces, and clock cases, for which purposes it is also employed in England. It is, however, sometimes used in this country for ecclesiastical decorative work, together with other marbles. Instances of its use to form a mosaic pavement may be seen in the chancel of Bristol Cathedral (1895), and in those of Truro (1886) and Peterborough (1892).

BGS Image ID: P576026

Marble specimen. Red Onyx. Ain Smara Quarries, Algeria.

Red Onyx. Alternative name: Rouge Agate. Specimen description: Crimson with white, pink, purple and orange veins and mottled markings. M Marius Cantini, Marseilles. 

Text from: Watson, J. British and foreign marbles and other ornamental stones. Cambridge : University Press, 1916:

 694 ROUGE AGATE. Ain Smara Quarries, Constantine. This example represents a much more brilliantly coloured variety of Constantine Onyx Marble than those already described. As the specimen shews, a rich crimson colour dominates, besides which, white, pink, amber, and purple are present in the form of mottled markings and ribboned veins, so that the rock resembles polished agate.

The Walter Brown Collection of marbles is held at the Scottish Mineral and Lapidary Club. They were photographed at the British Geological Survey.

Posted by Bob McIntosh

Landslip, Headon Hill, Totland Bay, 1921

BGI Image ID: P201811

Cliff N. side of Headon Hill, Totland Bay. Isle of Wight. Looking SW. Headon Beds, landslip in foreground. The white band in lower part of cliff is the Limnaean limestone (How Ledge Limestone) at top of Lower Headon Beds. The marine sandy clays of the Middle Headon Beds form the upper part of the cliff. White Limnaean limestone in the lower part of the Upper Headon Beds is indistinctly seen in the slope above the cliff. Ref: 'A short account of the geology of the Isle of Wight', p.115.

BGS Image ID: P201813

BGS Image ID: P201814

Mud-flow, Headon Hill. Fissured crust of mud-flow from slipped clays of the Headon Beds. The water in background is that of a pond in the hollow of a landslip. The fissures are due to a renewal of the slipping in the Lower Headon Beds.

BGS Image ID: P201815

On N. side of Headon Hill, Totland Bay. Looking NE. Mud-flow, Headon Hill. Concentric fissures in crust of mud-flow from the clays of the Headon Beds on the floor of a land-slip hollow. The fissures are due to a series of settlements originating to the right of the view.

Photographs taken March 1921.

Posted by Bob McIntosh

Granite from Ailsa Craig, Scotland

BGS Image ID: P521397

Rock specimen of riebeckite granite. Ailsa Craig, Firth of Clyde, Ayrshire, Scotland. British Geological Survey Petrology Collection sample number EMC3360.

The sample is a pale-coloured coarse-grained igneous rock with a distinctive granitic texture. It is technically a microgranite dominated by pale alkali feldspar crystals embedded in dark riebeckite amphibole and grey quartz.  The distinctive granite of Ailsa Craig forms part of the vast Tertiary Igneous Province of northern Britain. These formed around 60 million years ago. Much of the distinctive scenery of areas such as Arran, Mull, Ardnamurchan, Rum and Skye, and the Antrim Mountains in Northern Ireland, were formed as a result of this huge outpouring of magma. Because these rocks are well exposed and preserved they have been studied in great detail by generations of geologists, and provide an opportunity to study the deeper levels or 'roots' of volcanoes, from which we can learn much about currently active volcanoes today. The riebeckite granite of Ailsa Craig forms a Tertiary granite boss rising out of the Clyde estuary. It is one of a series of Tertiary granites. This blue-grey microgranite is very distinctive and has been extensively used as a marker for tracing the flow directions of Quaternary ice-sheets.

BGS Image ID: P750285

Another specimen of granite from the Ailsa Craig Quarry. British Geological Survey Petrology Collection sample number Econ. 1166.

BGS IMage ID: P001614

View of the old Ailsa Craig curling stone quarry situated on the north coast, Strathclyde Region, showing drilled-out stones 28 cm. in diameter in microgranite. 

The stone has a tough fine-grained lithology and can take a very high polish. It was worked in two colours, the 'red' and 'blue' varieties, the former was rarer and was much preferred. The curling stones were the economically most significant and world-renowned resource of the island. 50 pairs were exported annually in the 1870's rising to 1000 pairs in the 1890's. The quarry restarted 1961 but becoming uneconomic closed again in 1973.

BGS Image ID: P000704

BGS Old photograph number: D02015

Oblique aerial view of the island of Ailsa Craig. Looking south towards the north end of the island. The island is a very prominent landmark in the Firth of Clyde formed of a microgranite boss. Ailsa Craig is formed of an arfvedsonite-aegirine-microgranite intruded by vertical dyke swarms of olivine to alkaline olivine-dolerite with basalt margins. Isotopic dating using the Rb/Sr isochron method dates the microgranite at 61.5 Ma. This makes it Tertiary in age. The remains of the castle can be seen on the skyline on the left. It was built on the orders of the Earl of Cassillis by Thomas Hamilton whose coat of arms may be seen on the walls.

The resistance of the microgranite to erosion compared to the response to the soft Permo-Trias sandstones into which it was intruded was of crucial importance during the phase of glacial erosion. The principal direction of the ice during the last glaciation was south. This is indicated by the slight broadening of the island from north to south, albeit that this outline has been considerably modified by later marine action. The precipitous cliffs are primarily the results of marine erosion but the initiation of a strongly positive topographic feature associated with the microgranite intrusion probably occurred during glaciation.

Posted by Bob McIntosh

Kemnay Quarries, a working granite quarry, 1939.

BGS Image ID: P000136

Kemnay Quarries. Aberdeenshire. General view of the mason's yard. Stockpiled finished stone in a variety of sizes all neatly labelled can be seen in front of the masons' sheds. A steam train is seen mounted on a light railway. In the distance is part of No. 2 Quarry with several blondins stretched across the quarry. The roofs of the sheds could open to allow the travelling steam crane to deposit stone inside for the masons to work on.

BGS Image ID: P000132

Broken granite blocks after blast. Three quarrymen working at splitting a large block, one is wielding a pneumatic drill while the other two are using large crowbars.

Date of photographs: 1939.

An earlier post on Kemnay can be viewed here

Posted by: Bob McIntosh