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Book review … Volcanoes: Global Perspectives by John P. Lockwood & Richard W. Hazlett 4 July 2010

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A little while ago the people at Wiley-Blackwell got in touch to say that they had a new volcanology book out, Volcanoes: Global Perspectives by Lockwood & Hazlett, and would I be interested in reviewing it here on The Volcanism Blog. The answer, of course, was yes, and a review copy of the book speedily arrived. The review itself has, alas, not been so speedily delivered because of this blog’s recent hiatus, but here it is at last. In brief: I loved this book.

  • John P. Lockwood & Richard W. Hazlett, Volcanoes: Global Perspectives (Chichester: Wiley-Blackwell, 2010).

Cover image for Volcanoes: Global PerspectivesAs the preface makes clear, this book has been decades in the making, and it was well worth the wait. Volcanoes: Global Perspectives is a great overview of volcanology, an excellent textbook and a very good read. Some books on volcanism have as their central focus what volcanoes are; this one is as interested in how they are experienced, and it is this that gives it an extra freshness and energy. The authors emphasize throughout the importance of direct engagement with volcanoes in the field, and they waste no time in immersing the reader straightaway in their own dramatic first-hand experiences of eruptive activity at a ‘grey’ or explosive volcano (Galunggung, 1982) and a ‘red’ or effusive volcano (Kilauea, 1974). This is the kind of thing that makes people want to become volcanologists: it also firmly establishes in the reader’s mind the beauty and drama of volcanoes, their danger and their fascination, their complexity, their importance, and the manifold forms their activities take.

From there follows a lively, informal but crystal-clear exposition of practically every aspect of volcanism and volcanology that a reader wishing to be well-informed, whether specialist or not, needs to know about. Consciously avoiding specialist terminology, the authors nevertheless achieve the requisite detail and depth as they explain and explore the global context of plate tectonics that gives rise to volcanism, the nature and origin of magma, the characteristics of volcanic eruptions and their products, and the role of volcanoes and volcanism in shaping landforms. Finally, a fascinating final section of the book looks at ‘humanistic volcanology’, covering the significance of volcanoes in life, climate and human history, volcanic hazards and risks, and the economics of volcanism. It is admirable that these aspects of volcanism are not regarded as peripheral but are treated at length and in depth in this way.

Numerous well-chosen photographs and well-designed diagrams, maps, charts and tables illuminate the text, and throughout readers are invited to engage with the issues and test their own understanding through ‘questions for thought, study, and discussion’. The text in general is informal in style but clear and precise, always well-constructed, with a logical flow of analysis and many signposts to keep the reader’s progress through the potentially bewildering plethora of topics covered focused and on track. There are guides to further reading with every chapter, and the list of ‘references’ at the back constitutes an extensive volcanological bibliography.

It should also be mentioned that, despite its long gestation period, this book is very up-to-date: among the eruptions cited are the Chaiten eruption of 2008-10, the Hunga Tonga subsea eruption of March 2009, Sarychev Peak’s 2009 activity, and the deep-sea explosive activity found at West Mata in the Lau basin in May 2009 is described. The coverage of volcanoes and eruptions is truly global, and volcanism elsewhere in the solar system is not disregarded, being nicely explored in a section of the delightfully-named chapter ‘Volcanoes Unseen and Far Away’.

In summary, this book can be strongly recommended as a substantial but highly accessible survey of volcanism suited to specialist and non-specialist audiences alike. Readers in the latter group should not be put off by the apparent level of detail present in the book: some prior acquaintance with volcanology and some basic understanding of geology will be a help, but anyone who approaches the subject of volcanoes with enthusiasm, interest and a desire to learn will get a huge amount out of this book. It ought to reach the widest possible audience.

‘Volcanoes themselves are the best teachers of volcanology’ say the authors at the beginning of this book, and that is true; but superb textbooks such as Volcanoes: Global Perspectives are the next best thing.

Publishers’ page for Volcanoes: Global Perspectives.
An interview with the authors.
Review by Erik Klemetti at Eruptions.
J. P. Lockwood’s website.
Richard W. Hazlitt’s page at Pomona College.

The Volcanism Blog

Krakatau, 27 August 1883 27 August 2009

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'View of Krakatoa during the earlier stage of the eruption. From a photograph taken on Sunday the 27th of May, 1883' - plate I from The Eruption of Krakatoa and Subsequent Phenomena (London, 1888)

It was 126 years ago today, on 27 August 1883, that the most recent large-scale eruption of Krakatau (or Krakatoa, if you prefer) reached its final cataclysmic stage. An appropriate day, then, to draw the attention of interested readers to the fact that possibly the most detailed contemporary scientific study of the eruption, the Royal Society’s 500-page report on The Eruption of Krakatoa and Subsequent Phenomena (1888), is freely available to download from the Internet Archive.

Fgures 2 and 3 from The Eruption of Krakatoa and Subsequent Phenomena (London, 1888)

The book has been fully digitized by Google, but it is a curious fact that Google chooses not to make the full text of this out-of-copyright publication available via Google Books. It is, however, freely available to read and download (along with many other texts that Google has digitized but has seemingly decided to keep to itself) through its inclusion in the Internet Archive.

The Eruption of Krakatoa and Subsequent Phenomena can be accessed via this page at the Internet Archive. The PDF of the entire book (27.2 MB) cannot be found via the ‘Google.com’ link given on that page, but can be downloaded through this direct link.

The Volcanism Blog

Aesthetic geology – Sir William Hamilton’s ‘Campi Phlegraei’ 14 June 2008

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[This article is written as a contribution to Accretionary Wedge #10, ‘Aesthetic Geology’, which is being hosted by Geological Musings in the Taconic Mountains.]

For an article addressing the topic ‘aesthetic geology’ it seems appropriate to look at what is certainly one of the most aesthetically beautiful geological works ever published: Sir William Hamilton’s Campi Phlegraei: Observations on the Volcanos of the Two Sicilies (1776).

Sir William Hamilton (1730-1803), perhaps best-known today as the husband of Emma Hamilton, mistress of Admiral Lord Nelson, was in his own right a skilled diplomatist, a celebrated connoisseur and collector, and a respected natural historian. In his own time he was honoured in particular for his contributions to the study of volcanoes, acquiring the title ‘the modern Pliny’ for his studies of Vesuvius.

Campi Phlegraei (1776) - plate III, view of Naples

Above: Campi Phlegraei, plate III, a view of Naples. This view shows Naples and Vesuvius as a harmonious whole, with traffic on the road and vessels in the bay serving to illustrate the place of the volcano as part of the city’s daily life. The figures reacting to their surroundings draw the viewer in and emphasize the importance of an active engagement with the landscape.

Hamilton arrived in Naples as British envoy to the Neapolitan royal court in 1764, and became fascinated by Vesuvius. Shortly after his arrival the volcano went into an eruptive phase that lasted until 1767, giving Hamilton ample opportunity to observe and report upon its behaviour. In 1766 he was elected a Fellow of the Royal Society and the core of his volcano studies was contained in a series of letters written to be read aloud at the society’s meetings and published in its Transactions. It was these letters that were collected together into one volume as Campi Phlegraei in 1776. The text was accompanied by fifty-four lavish illustrations, prepared by the artist Pietro Fabris under Hamilton’s direction, and hand-coloured. The resulting volume was very expensive to produce, and placed a great deal of strain upon Hamilton’s always fragile finances, but has become celebrated as one of the great monuments of eighteenth-century science.

Campi Phlegraei (1776) - plate VI, view of the 20 October 1767 eruption of Vesuvius

Above: Plate VI of Campi Phlegraei shows the eruption of 20 October 1767. On the left is the harbour breakwater or mole of Naples, with its lighthouse, and shipping in the harbour. A lava flow is spreading as it descends the flanks of the volcano towards the sea; lightning is visible in the eruption cloud. This night-time view of Vesuvius is one of the most dramatic illustrations in Campi Phlegraei, with the volcano as a grand and sublime object. Yet the peaceful harbour in the foreground suggests that the works of man can co-exist with the volcano.

Hamilton believed passionately in the importance of careful, direct observation of natural phenomena, and Campi Phlegraei is intended to make the various aspects of Vesuvius’s activity available to those unable to see the volcano directly themselves. He ensured that Fabri’s illustrations were as accurate and detailed as possible, reflecting his aim of offering ‘accurate and faithfull observations on the operations of nature, related with simplicity and truth’. The desire to view phenomena directly for oneself, and to form one’s own opinion on the basis of the evidence, can be seen as a central principle of the Enlightenment.

Campi Phlegraei (1776) - plate XII, 1760-61 eruption of Vesuvius

Above: Plate XII of Campi Phlegraei is a dramatic scene of advancing lava flows from the eruption of December 1760 to January 1761. Hamilton used the original caption of this image to argue against those who believed that the seat of a volcano’s ‘fire’ was always near the summit.

One of the fundamental debates of eighteenth-century geological study was whether volcanoes represented peripheral or central phenomena in the structure and workings of the Earth. ‘Neptunists’ argued for the sedimentary origin of all rocks and believed volcanoes were the superficial result of localized combustion, having no geological significance; ‘Plutonists’ saw heat as the most important agent in the history of the planet, with volcanoes as an essential expression of its operation. Hamilton’s observations of Vesuvius, and his reading of the surrounding landscape in terms of the volcanism of the past, led him to the conclusion that volcanoes were a central geological phenomenon, based on a deep-seated heat source, and that there had been volcanic action throughout the history of the Earth. He also saw volcanic action as a positive, creative principle, producing fertility, reshaping the landscape, an agent of re-creation rather than destruction. The illustrations in his Campi Phlegraei convey the grandeur and power of the volcano, but also seek to embody and convey these ideas: they aim to communicate information as well as to inspire wonder. They are an expression of a new scientific aesthetic.

David Constantine, Fields of Fire: A Life of Sir William Hamilton (London: Weidenfeld & Nicolson, 2001)
Ian Jenkins & Kim Sloan (eds.), Vases and Volcanoes: Sir William Hamilton and his Collection (London: British Museum Press, 1996)
Joachim von der Thüsen, ‘Painting and the rise of volcanology: Sir William Hamilton’s Campi Phlegraei, Endeavour, vol. 23, no. 3 (1999), pp. 106-109
Karen Wood, ‘Making and circulating knowledge through Sir William Hamilton’s Campi Phlegraei, British Journal for the History of Science, vol. 39, no. 1 (March 2006), pp. 67-96

Sir William Hamilton, Campi Phlegraei – Glasgow University Special Collections Department
Sir William Hamilton, Campi Phlegraei – Georgetown University/Campania Libraries
Campi Phlegraei – from the Science Museum Library

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The latest volcanoes in the British Isles – a lecture from 1895 3 June 2008

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[From The Liverpool Mercury, 26 December 1895, p. 2]

The presidential address in connection with the Geological Society of Glasgow was delivered by Sir Archibald Geikie, the Director-General of the Geological Survey of Great Britain.

Sir Archibald Geikie said his first duty was to thank the members of the Geological Society for the honour conferred upon him some time ago in electing him their president. He had a keen interest in the society. It was now more than 30 years since that connection began, and one of his earliest papers was published in the first volume of their transactions. Although he had no prepared address to deliver to them that night, he proposed to speak to them on a subject that had occupied him closely for the last 20 years, and more particularly the last seven — the story of the last volcanoes in eruption in the British Isles. Our islands were especially fortunate in the wonderfully complete record which we had within our borders of the history of volcanic action, and these were nearer than the time of the soft clays on which London was built. There was an almost continuous line of volcanic eruption along the western border of the European Continent. Our country was placed on what one might call the critical line of the European Continent. He proposed to sketch rapidly the story of the last volcanoes. These were active along the great line of valleys between the Outer Hebrides on the west and the mainland of Scotland on the east, and they extended from the South of Antrim right through that hollow, through the line of the Inner Hebrides, and on to the Faroe Islands. During the last two years he had been able to extend his researches amongs those rocks in the Faroe Islands, and he had been specially interested to find that the story of volcanic action was told there even more fully and more clearly than it was within our own islands, a result partly due to the difference of climate, greater denudation, and the greater height. The Icelandic geologist — for there was really only one — complained that geologists in their text-books and in their memoirs had been in the habit of quoting Etna and Vesuvius as types of volcanic action, and pointed out that in Iceland they would find the most potent forms of volcanic activity. He sympathised with that geologist, for he found that the story of our own volcanic history was more clearly made known by the study of the Icelandic volcanoes. One of the first features that struck them in looking at the history of the modern Icelandic volcanoes was that they did not form mountains like Etna or Vesuvius, but were the production of great fissures. When a volcanic eruption was to take place the ground seemed to have been rent into long, rectilinear fissures, of which two series at least had been discovered — one running in a north and south line, and the other running from south-west to north-east. In some cases the lava had risen up through these fissures, and flowed out tranquilly now to one side and now to the other. Most frequently it happened, however, that the lava formed great long lines of volcanic cones so close together that they actually touched each other. From the base of these cones the lava streams flowed now to the one side and now to the other, and solidified over the surface. As each eruption occurred the surface was again covered over, and so altered the topography of the country. In some cases the intervals between the outpourings of lava would be very considerable, and along the western coast of Skye and the west of Mull there was found a red layer with one of dark, almost black, rock on the top of it. Sir Archibald Geikie referred to the fact that last year, when yachting among the Western Islands, he discovered some new facts of considerable importance in considering the volcanic action in that region. Last year he also visited the Faroe Islands, and was able at one part to trace distinctly no less than five old volcano vents which had been completely buried by about six, eight, or perhaps even ten thousand feet of volcanic material. He also referred to a visit which he was able to pay to St. Kilda this year, and to get to the junction of the two masses of rock. He found the black gabbro riddled with a network of fine light-coloured rock, such as was found in Mull of Skye and Rum, but on a much larger and grander scale than in any of these islands. He hoped to be able to make a more thorough examination next year, if the weather would permit him. The volcanic period of which he had been speaking belonged to a very recent geological period — and belonged to a time actually later than the soft clay on which the city of London was built. He concluded by referring to the interesting shores of the Faroe Islands, where the imagination, which was apt to be carried away by the contemplation of scenery so splendid, was always checked by those solemn, unmoved lines always in front of them, and where they could actually obtain numerical data to control them. (Applause.)

Sir Archibald Geikie (1835-1924) – biography from NAHSTE
Sir Archibald Giekie (1835-1924) – another biography from Scottish Geology
Sir Archibald Geikie, The Scenery of Scotland (1887) – an online edition prepared by Dr David C. Bossard
Geographical Evolution: An Introduction – text of an 1879 lecture by Geikie

The Volcanism Blog

J. Logan Lobley’s ‘Mount Vesuvius’ (1889) 1 April 2008

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A nineteenth-century volcanological work available for free and in full via the Internet Archive‘s American Libraries project: J. Logan Lobley, Mount Vesuvius. A Descriptive, Historical, and Geological Account of the Volcano and its Surroundings (London: Roper & Rowley, 1889).

Mount Vesuvius, the world-famed volcano of Southern Italy, has been for many centuries an object of great interest to the inhabitants of Europe. In ancient times, the conspicuous position of the mountain in one of the fairest and most frequented portions of the Roman dominions – the resort of the most wealthy, most famous, and most noble of the citizens of Rome – and the terrible character and dreadful results of the eruption of the year 79, combined to render Vesuvius an object of especial interest and wonder.

List of chapter headings: I: The Neapolitan volcanic region. II: The surroundings of Vesuvius. III: The mountain. IV: History to 1850. V: History: 1851-1868. VI: History: 1869-1888. VII: Geology of Vesuvius. VIII: Volcanic action. IX: Volcanic products. X: The minerals of Vesuvius. XI: The flora of Vesuvius.

The author was Professor of Physiography and Astronomy at the City of London College, and author of Geology for All (1888) among many other things.

Read Mount Vesuvius, in a choice of formats, here.

The Volcanism Blog

Volcanoes, Basalt, and the Discovery of Geological Time: an online exhibition 30 March 2008

Posted by admin in history of volcanology, images, volcano culture, volcanological works, web resources.
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‘Vulcan’s Forge and Fingal’s Cave: Volcanoes, Basalt, and the Discovery of Geological Time’ was an exhibition presented at the Linda Hall Library, Kansas City, Missouri, from October 2003 to March 2004. Why tell you about an exhibition that closed four years ago? Because, thanks to the LHL’s enlightened and imaginative approach to the internet, it left a wonderful website behind it.

The exhibition presented over sixty rare books and journals from the period 1650-1830, representing changing perceptions of basalt and the significance of the understanding of basalt’s igneous (as opposed to aqueous) nature and of the phenomenon of volcanism for the growing recognition of the immensity of geological time. The online exhibition is divided into seventeen richly-illustrated sections which display sixty-six printed items dealing with basalt and volcanism, many of them spectacular and beautiful as well as fascinating. The presentation of these items is crystal-clear and immaculate, the texts are informative and thought-provoking, and the organization and navigation is straightforward.

Vesuvius and EtnaBasalt along the RhineDerbyshire Toadstone … it’s all here. Highly recommended.

Vulcan’s Forge and Fingal’s Cave – entrance page for the online exhibition
Online Exhibitions – Linda Hall Library – list of the online exhibitions available at the LHL
Linda Hall Library of Science, Engineering & Technology – main page for the LHL

The Volcanism Blog

The life history of a volcano: a lecture from 1891 22 February 2008

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A Geological Study.

[From The Leeds Mercury, 30 May 1891, p. 5]

At the meeting of the Leeds Geological Association on April 21st, in the absence of Mr. S. Chadwick, F.G.S., who was announced to read a paper on “Flint from the Yorkshire Chalk,” a lecture on “Volcanoes” was given by the Hon. Secretary (Mr. W. L. Carter, M.A., F.G.S.) illustrated by a number of beautiful lantern slides.

What is a volcano? The old answer was, “A burning mountain, from the summit of which issue flames and smoke.” This, the lecturer said, was a misconception from beginning to end. A volcano is essentially an opening in the earth’s crust communicating with the heated interior. The volcanic mountain is the mass of materials which has been ejected from this aperture. A volcano does not burn, “i.e.,” there is no combustion at the summit, but it emits large quantities of steam and fine ash, which together form the so-called smoke, and streams of white hot lava, the flashing light from which reflected by the overhanging clouds looks like flame. The name “volcano” comes from the Island of Vulcano, near Sicily, which was styled by the ancients “The Forge of Vulcan.” This volcano is now fairly quiescent, and a chemical works was established in the crater some years ago, by an enterprising Scotch firm, for the condensation of the sulphurous and other chemical gases which it gave off. One night, however, an eruption took place, blowing the manufactory into the air, and effectually stopping that branch of industry. One naturally turns to Italy for examples of volcanoes, because it is easily accessible, and illustrations of all stages of volcanic action are found there. There are three Italian volcano districts — (1) the Roman, in which there is no active vent, but perfect craters and great crater lakes; (2) the Sicilian; and (3) the Neapolitan, both of which are partly terrestrial and partly marine. With regard to the supposed connection of the sea with volcanic action, as a source of water-supply, it is interesting to note that the two regions which still touch the sea are active, whilst the Roman region, which has been separated from it by the advance of the coast-line, is extinct.

Formation of the volcano.

One especially good instance of the birth of a volcano has been recorded by four eye-witnesses. In September, 1858 [sic: clearly an error, the correct date is 1538], Monte Nuovo, a hill 430 feet high, and 8,000 feet in circumference, was raised in three days on the shore of the Bay of Naples. There had been earthquakes for two years, which increased in frequency, when a fissure was formed which emitted springs, first of cold and then of boiling water. On Sunday night, September 29th, the earth suddenly burst open, and great quantities of ashes mixed with water were ejected, covering the country for miles round, and the sea retreated for some distance. No lava issued from the cone, which was entirely composed of ashes; and there has been no eruption on the same spot since. Thus is formed the simple volcanic cone. Passing on to more mature stages of volcanic existence, we will take Vesuvius as an example. In prehistoric times, this mountain would have formed a perfect cone, the top of which, being blown away, produced the wide crater-plain which existed up to A.D. 79. Previously there is a no record of volcanic activity, but in that year the western side of the old volcano was blown away, and a new cone formed. By this eruption Pompeii and several other towns in the district were destroyed. Since then the volcano has been in constant activity. Vesuvius is divided into several zones. The lower cultivated slope, merging into the plain, is composed of disintegrated volcanic rock, and is very fertile. This extends to 1,500ft. above the sea-level. The Desert Platform, a barren and desolate waste continually invaded by fresh lava streams, reaches from 1,500ft. to 2,500ft. On the eastern side is the ridge of Monte Somma, which half encircles the active vent, and is part of the original cone destroyed by the eruption of A.D. 79. The present cone is three miles in circumference, and 1,500ft. in height above the Desert Platform. The summit alters with every eruption, and smaller secondary cones are formed inside the chief crater. Etna is a more complex example of the colossal volcano. It is 10,840ft. above sea-level, and there are several zones of vegetation between the base and the desert region. There you see nothing but scoriae, lava, and snow. The great height of this cone causes the hydrostatic pressure in the central pipe to be too great to allow of the lava now reaching the central crater; and by the yielding of the sides, parasitic or daughter cones are formed. At subsequent stages in the existence of a volcanic cone the ground underneath becomes fissured, and an easier vent for the volcanic forces being thus provided, small cones or puys are formed in the plain around the base of the volcano.

The Eruption.

As an example of a great eruption, we may take that of Vesuvius in 1872, in which several adventurous tourists lost their lives. The flow of lava was so profuse that Professor Palmieri wrote — “The cone seemed completely perforated, and lava oozed, as it were, through its whole surface. I cannot better express it than by saying — Vesuvius sweated fire.” Terrific discharges took place from the summit, ejecting enormous quantities of steam and ashes, reaching 5,000ft. above the top of the mountain, which were carried slowly along by upper air currents. Darkness was produced over a considerable area, and the rain of ashes devastated the crops and caused great alarm. One lava stream on the western side carried away large portions of two villages and so rapid was its flow that the villagers were barely able to save their portable possessions, and some lost everything. The decadence of the eruption was accompanies by a storm of thunder and rain, which brought down the hurtful gases and salts from the great cloud, shrivelling up grass, vines, and trees. Eruptions are not, however, always so violent as this, and in the case of Stromboli the sequence of events can be watched at close quarters without danger. Stromboli is a volcanic cone near Sicily, which rises out of the Mediterranean to a height of 3,090ft. and has been in constant activity for at least 2,000 years. The crater is in the side of the mountain, and from it clouds of vapour issue continually. The outbursts occur at intervals of from one to twenty minutes, and are unequal in intensity. By care an observer can climb to a point above the crater and watch the eruption. The black slaggy bottom of the crater is traversed by fissures, from which many jets of vapour curl quietly up. From larger apertures bursts of steam take place at intervals and molten rock wells out. In other openings a viscid substance is seen slowly heaving up and down, until a gigantic bubble is formed, which, bursting violently, sets free a great mass of steam, which carries great fragments of the molten rock high into the atmosphere. Thus in this working model, as it were, of a volcano, we see the essentials of all volcanic eruptions: — 1. The existence of apertures communicating with the interior of the globe. 2. The presence of lightly heated matter beneath the surface. 3. Great quantities of subterranean water, which by contact with this molten rock becomes suddenly converted into steam. These three conditions explain eruptions alike on the smallest and the largest scale.

Products of Eruption.

Many vapours are given off by a volcano, including acid gases, such as chlorine, hydrochloric acid, and sulphurated hydrogen. In less active stages carbonic acid is emitted in large quantities. Steam, however, is the most important vaporous product of volcanic action, forming 990-1000ths of the whole cloud. It has been calculated that during an eruption at Etna, which lasted one hundred days, that the steam emitted each day would, if condensed, have produced four and a half million gallons of water. Thus we cannot be surprised that floods of water play a considerable part in the devastation which accompanies a volcanic eruption. These water floods are produced either by the condensation of steam, or by the melting of masses of snow, owing to the rapid rise in temperature, or by the disruption of subterranean reservoirs. An instance of the last was seen in Java in 1817, when a lake of hot, acid water, filling a large crater, was suddenly discharged, with frightful destruction. Water rushing down the cone collects the volcanic dust, and forms a mud lava, which afterwards consolidates into tuff. It was by such a mud lava that Herculaneum was engulfed in A.D. 79. Various fragmentary materials are ejected by the force of an eruption. The finest of these form a light grey powder called ashes, though they are not products of combustion. So fine is this ash that Mr. Whymper estimated that though two millions of tons were ejected in one eruption of Cotopaxi, there would be from 4,000 to 25,000 particles in each grain weight. During an eruption in Nicaragua in 1835, there was darkness over an area of thirty-five miles in radius; the ground twenty-four miles from the mountain was covered ten feet deep, and the ash fell 700 miles from the centre of eruption. Larger fragments, from the size of a pea to that of a walnut, and great blocks, are often ejected from volcanoes. In Java, in 1772, a vally nine miles long was filled with angular blocks to a depth of 50 feet. Volcanic bombs, which are lumps of lava, rounded by rapid rotation as they move through the air, are found in almost all sizes. Lava is molten rock resembling slag. It is white hot at its exit from the crater, but soon becomes a dull red. Lavas differ in liquidity according to the amount of the included steam, and also according to their chemical composition and temperature. Viscous lavas give off very little steam and take on ropy structure owing to the crinkling of the cooling surface by the continued movement of the lower layers. Liquid lavas give off much steam, are rapid in flow, and form a sharp, cindery surface. Trachytic (basic) lavas from thin, widely extended sheets. The enormous size of some lava streams may be estimated from the fact that the flow from one eruption in Iceland would form a mountain greater than Mont Blanc.

Volcanic Decrepitude.

Having thus dealt with the mature and vigorous volcano, it remains to enumerate the characteristic of its declining strength. These consist largely of vaporous emanations. A notable instance is that of the Solfatara, a crater in the Phlegraean (Burning) Fields to the north of Naples. It evolves gases and sulphurous fumes, depositing pure sulphur. Its last eruption was in 1198. Geysers (gushers), which are eruptive fountains of water and steam, exist in areas of decaying volcanic activity. Sinter cones and terraces are also formed by the emission of hot springs holding silica in solution. At a further stage carbonic acid gas alone is given off, as in the case of the Dog’s Grotto near Naples. Extinct craters are found in many parts of the world, and there are many examples in the Phlegraean Fields. The largest is Astroni, which is one mile in diameter, having in the centre a boss of trachytic rock, which probably is the plug of the old vent. Now the crater is overgrown with oaks and undergrowth, and is used as a Royal preserve for hunting wild boar and other big game.

Dissected Volcanoes.

The action of atmospheric agencies on extinct volcanic cones gradually lays bare their innermost parts, and reveals many interesting details of structure. There have been in times past several volcanoes in Britain larger than Etna. The Mull volcano, which was once upwards of 12,000ft. in height, is now reduced to a group of hills about 3,000ft. high. In Skye there is the wreck of a similar colossal cone, and Ben Nevis is carved from the inner masses of another such mountain. Arthur’s Seat, Snowdon, and Cader Idris are also formed of volcanic rocks. That volcanic action is not yet entirely spent in the British area is evidenced by hot springs and earthquakes. The hot spring at Bath, for instance, pours forth daily 180,000 gallons of water at 120 degrees Fahrenheit, and it is said that the materials which it has brought to the surface in solution during the last 2,000 years would be sufficient to form a cone as large as Monte Nuovo. Earthquake shocks are also occasionally felt in our country, such as that which did so much damage in Essex and Suffolk a few years ago, showing the existence of pent-up forces beneath the surface. The successive stages in the existence of a volcano have thus been traced from its earliest commencement in a mere fissure, around which a simple cone was built up, to a colossal volcano such as Etna, with numerous daughter cones. From this period of full maturity we have followed the fiery giant into a state of decrepitude, when he is able to fume and nothing else. Then comes the period of extinction, and as time goes on the cone is broken down by atmospheric denudation until its hidden framework is brought to light, and entering nature’s dissecting-room we are able to study the anatomy of the volcano, and thus many of the mysteries of its life history are made clear to us.

An interesting discussion followed, in which Messrs. Thrippleton, Jefferson, Bedford, and the President took part, and the thanks of the meeting were unanimously given to the lecturer, and to Mr. Bedford for his management of the lantern. A hearty vote of thanks also was accorded to those who had lent lantern slides, and especially to Mr. Branson for a splended series of Italian views.

The Volcanism Blog

‘Fiery Mountains’: volcanoes in Sir Thomas Pope Blount’s ‘Natural History’, 1693 17 January 2008

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The English author and essayist Thomas Pope Blount (1649-97) published A Natural History: Containing Many not Common Observations: Extracted out of the best Modern Writers, in 1693. As its subtitles suggest, this was a work of synthesis rather than direct and original observation. Blount was a tireless reader and accumulator of other writers’ wisdom – his most notable work, Censura celebrorum authorum (1690), was a collection of things famous authors had said about each other – and in this work he brings together observations from a wide range of contemporary authorities, accommodating them in an overall argument which reflects a belief in the divine authorship of the universe. As he writes in his preface, ‘Every Flower of the Field, every Fibre of a Plant, every Particle of an Insect, carries with it the Impress of its Maker, and can (if duly consider’d) read us Lectures of Ethicks or Divinity’. Among the aspects of natural history that Blount considers are ‘VULCANO’s, or SUBTERRANEAN FIRES’ (pp. 388-402; further page references appear in brackets below).

Blount reflects the common view of his era, prominent in discussion of volcanoes from the sixteenth century to the eighteenth, that volcanism is produced by the combustion of minerals beneath the surface of the earth.

There are Subterraneous Cavities, which they call VOLCANO’s, or Fiery Mountains; that belch out Flames, Smoke and Ashes, and sometimes great Stones and broken Rocks, and Lumps of Earth, or some Metallick mixture; and throw them to an incredible distance by the force of the Eruption. These argue great vacuities in the Bowels of the Earth, and Magazines of Combustible Matter treasur’d up in them. And as the Exhalations within these places must be copious, so they must lie in long Mines or Trains to do such great Execution, and to last so long. (388-9)

He draws on the writings of Thomas Burnet (1635-1715), whose Telluris Theoria Sacra (The Sacred History of the Earth) was published in 1681 and depicted the earth pierced and hollowed out by inner cavities, many of which were at times filled with fire. The effects of these ‘Magazines of Fire’ can be seen across the globe:

… throughout all Regions and Countries, in the West-Indies and in the East, in the Northern and Southern parts of the Earth, there are some of these VOLCANO’s, which are sensible evidences that the Earth is incompact and full of Caverns; besides, the roarings and bellowings that use to be heard before an Eruption of these VOLCANO’s, argue some dreadful hollowness in the belly or under the Roots of the Mountain, where the Exhalations struggle before they can break their Prison. (393-4)

Burnet, a clergyman, saw the wrinkled, uneven surface of the earth as evidence of the Fall of humanity from the pristine innocence of the Garden of Eden, and the presence of volcanoes as a sign that the world was filled with fires which would eventually destroy the entire planet. Blount argued from the evidence of Vesuvius and Etna that the power of volcanic action was declining over time, observing that the ‘Eruptions of VESUVIUS seem to be more frequent and less violent of late’ (388), and that in Etna’s case ‘these Eruptions of Fire are not now so ordinary as formerly; the matter which gave Fuel to it, being wasted by continual Burnings’ (397), which would not support Burnet’s view. Indeed, Blount does not pursue Burnet’s cosmogeny to its catastrophic conclusion: he is more concerned with the practical questions of why volcanoes are there and how they work, and in particular ‘what can be the Fuel of so lasting a Burning, that hath calcin’d so much matter, and spew’d out such prodigious quantities’ (395). Along with many of his contemporaries, influenced by the heritage of alchemical experimentation, he believed that sulphur played a vital role in feeding the fires of volcanic activity:

It is plain there are vast Veins of SULPHUR all along in this Soil, and it seems in this Mountain they run along through some Mines and Rocks, and as their slow Consumption, produceth a perpetual Smoke, so when the Air within is so much ratified that it must open it self, it throws up those Masses of Mettle [i.e. metal] and Rock that shut it in; but how this Fire draws in Air to nourish its Flame, is not so easily apprehended; unless there is either a Conveyance of Air under Ground, by some undiscover’d Vacuity; or a more insensible transmission of Air, through the Pores of the Earth. (395)

Such vast subterranean fires would demand a great supply of air, and Blount again reflects the wisdom of his time (and draws on theories that had their origin in Ancient Greece) in suggesting that powerful winds blow constantly through cavities and vacancies in the earth. These imprisoned winds sustain the processes of underground combustion and, by forcing openings in the rock itself, producing vents through which the fires gain access to the surface: ‘the Subterranean Winds kindle and eject these Fires, and open the mass of Earth, under which they are shut up’ (399).

Blount dismisses the notion that these underground fires are ignited by chance events such as lightning strikes and sparks from ‘one Stone striking another’ (399), favouring instead the argument of Dr Martin Lyster, put forward in a paper on ‘Of the Nature of Earth-quakes’ in the Philosophical Transactions (1683), that combustion is innate to the substances concerned:

That Learned Physician, and most Sagacious Inquirer into Nature, Dr. Martin Lyster, saith, That amongst Minerals, the Pyrites, both in Gross and in Vapour, is actually of one accord fired. He instances the VULCANO’s all the World over for a proof of it; for, saith he, we with great probability believe them to be Mountains made up in great part of Pyrites (the Breath whereof is SULPHUR Ex tota Substantia,) by the qualities of SULPHUR thence Sublimed, and the Application of the Load-Stone to the Ejected Cinder. (400-1).

Taking up Lyster’s argument that ‘these VULCANO’s were naturally kindled of themselves, at or near the Creation’, Blount conveys the notion that volcanoes are not inharmonious intrusions into the world but are a natural expression of the combination of elements brought together in a divinely-ordered universe: ‘it seems to me, saith the Doctor [Lyster], as natural to have actual Fire in the Terrestrial World from the Creation, as to have Sea and Water‘ (401-2).

Volcanoes posed a problem to those who saw the universe as the harmonious and beautiful creation of a beneficent deity: they appeared ugly, destructive, violent and purposeless. Blount ends his discussion of volcanoes by suggesting that they can be accommodated as an aspect of an overall balance of fundamental elements. They are a part of the divinely-created fabric of the universe.

Sir Thomas Pope Blount, Bt., A Natural History: Containing Many not Common Observations: Extracted out of the best Modern Writers (London: R. Bentley, 1693).

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James Little: a rector writes on volcanoes, 1820 5 December 2007

Posted by admin in history of volcanology, Tambora, volcanological works, volcanology.
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In 1820 the Rev James Little, rector of the Irish parish of Lackan, published Conjectures on the Physical Causes of Earthquakes and Volcanoes, in which it is proposed to explain these Phœnomena on a New Hypothesis, of the Structure of the Earth, and of the Existence of an Internal Atmosphere communicating with ours (references to the pages of this work are given in brackets below). As is so often the case with works of this period, the subtitle gives away the main argument: Little was an advocate of theory of the hollow Earth, and believed that fire constantly rushed through vast empty spaces beneath the Earth’s surface, undermining it (leading to earthquakes) and occasionally breaking through to the atmosphere above (producing volcanoes).

Little was convinced that his era was characterized by an ‘unusual frequency of Earthquakes and Volcanic Eruptions’ (4), an unusual perception at a time when most geologists held that these phenomena had been more marked in the past than in the present. He refers to ‘the more rainy and inclement seasons, especially of the present (1817) subsequent to them’ (4), suggesting that he may have been thinking in particular of the recent cataclysmic eruption of Tambora in 1815 and its marked effects upon global climate; and indeed he describes the eruption of ‘Tamboro’ in some detail (23-5).

Little’s theory of the interior structure of the Earth does not depend upon the entire globe being hollow, but envisages a highly complex system of interconnected cavities. He writes that ‘a considerable part, if not almost the whole of the surface of this globe, both land and water, is undermined with cavities, set on fire, scattered irregularly underneath its surface’ (53). His conception of this network of cavities is almost architectural, and echoes contemporary notions of the sublime:

… this surface resting on the solid parts variously posited; like a tract of Bridges ramified in every direction, and formed of irregular arches, varying in span, in breadth, and in order of position; resting on their abutments; and some of them of the fearful dimensions of a thousand miles square, sometimes violently shaken throughout their whole extent, and (as we might from any thing except our confidence in the Architect, justly apprehend,) in danger from this construction, of one day falling down, far beneath the ocean, into a warmer bed than appertains to it. (53)

As the mention of the beneficent ‘Architect’ above underlines, Little was a clergyman, and his discussion of volcanic activity is naturally informed by his Christian standpoint. He is concerned, as were many of his contemporaries, to find an interpretation of such destructive phenomena consistent with the idea of a loving God, arguing that the earth tremors that always accompany volcanic eruptions serve as a warning mechanism:

I recite chiefly the accounts of the eruptions of volcanoes, because these are always attended by the shocks of Earthquakes, more or less violent … both arise from the same cause, and that the former are the preservative appointed by the author of nature, against the destructive effects of the latter. (5)

His attempts to argue through this conviction lead him to a recognition that the apparently unstable structure of the Earth’s surface hardly seems to possess the harmonious and enduring character of divine creation: ‘I confess I deem more reverendly of the beauty and solidity of the architecture of the Deity, than to suppose that such a structure came from his Hands’ (53). Yet his conviction that God has built warning mechanisms into His creation, and that it is the duty of humanity to understand and heed those warnings, reconciles the apparent contradiction and enables Little to point a moral with wider application: ‘However, He may contrive to warn us mortals, that we rest only on His unknown foundations, which will fail partially or totally when He pleases, but not from their own instability’ (53).

As for the ‘fires’ of volcanism, Little rejects the theory that they are ‘produced by combustible minerals existing in veins and caverns in the bowels of the earth and spontaneously igniting and exploding’ (39), but does not really make any attempt to put forward a theory of his own, taking refuge in a theological explanation of the presence of fire beneath the earth’s surface:

… we must suppose the existence of subterraneous fire, which so often and in so many places makes its terrific appearance; and it must either be casually kindled in separate vaults … or permanently undispersed and lining the concave surface of the shell of the globe. I confess the latter to be my opinion, and that the more just and philosophical description of it is that given by the sublime prophet Isaiah; ‘that Tophet is ordained of old, yea for the King is it prepared; he hath made it deep and large; the pile thereof is fire and much wood; the breath of the Lord, like a stream of brimstone doth kindle it.’ Isaiah 33.33. (61)

Little’s work is a mixture of scientific observation and religious explanation. He had an interest in scientific matters, having published A Description of a Reflecting Level or an Artificial Horizon for taking Altitudes of the Celestial Bodies, &c. in 1800, and was well-read in accounts of earthquakes and volcanic eruptions, noting that earth tremors always precede the latter (5), and that the eruptions of volcanoes such as Vesuvius tend to follow settled sequences of events (18). He also notes ‘the elevation of the surface of that region where the shock is to be’ in the case of many earthquakes (93). In interpreting the ‘fires’ of volcanism as a form of combustion he was representative of the scientific orthodoxy of his era. When he comes to explain these phenomena, however, he writes as a Christian minister, seeking messages of divine benevolence even in the destruction of earthquakes and volcanoes, and finding hellfire rushing through the caverns of the underworld.

The Rev. James Little, Conjectures on the Physical Causes of Earthquakes and Volcanoes, in which it is proposed to explain these Phœnomena on a New Hypothesis, of the Structure of the Earth, and of the Existence of an Internal Atmosphere communicating with ours (Dublin: James Byrn, 1820).

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