In the short Preface, the authors state that their intention is to provide a major advance on the precursor volume by Cas & Wright (Reference Cas and Wright1987) by…‘providing much more detail on key concepts, processes, and deposit characteristics; and providing a comprehensive bibliography of each of the major topics addressed’. In that context, the three authors have succeeded admirably. References are comprehensive and up-to-date (2024). The book is an invaluable resource that all professional volcanologists, whether in industry, universities or government institutes, should have on their shelf, or an e-copy. The text is also understandable by graduate students and it should form the nucleus of university volcanological lecture courses for the foreseeable future. As a specialist on glaciovolcanism, a topic that was largely unknown in 1987, I welcome the additional text on volcanoes that erupted in glacierized terrains, reflecting some of the many advances made in that distinctive category of hydrovolcanism.
In the Introduction, the authors state that ‘a major aim of the book is to provide students and geoscientists with the approach and basis for making their own interpretations and reconstructions of modern, historical and ancient eruption sequences. Therefore, the book will also briefly address methods and approaches that may be useful in documenting and analysing both modern and ancient successions. The book is not an encyclopaedia, and although we present a balanced overview and review of processes and interpretations, we also present our own personal insights and assessments as research scientists with considerable experience in the range of topics discussed’.
The book is long, with over 1800 pages, although perhaps close to half is taken up by excellent diagrams and photographs. For comparison, Cas and Wright (Reference Cas and Wright1987) was ‘just’ 528 pages. An important feature of the new volume is the definition of multiple volcanic eruption types, far more than were previously recognized, as a result of the explosion of interest (with apologies for the pun) and research in volcanology since 1987. Thus, in addition to well-known and long-established eruption types, such as Surtseyan, Hawaiian, Strombolian, Plinian, sub-Plinian, Vulcanian and phreato-Plinian, additional eruption types are identified that many readers may be much less familiar with (some were also unfamiliar to this reviewer), including Ukinrekian, ultra-Plinian, micro-Plinian, phreato-Strombolian, Halemaumauan, Yalian, Poseidic, Neptunian, phreato-Vulcanian, Hunga-Tongan and Tangaroan-Havre. Each type is described, with explanation of how it formed and the characteristics of the deposits, although some deposits are difficult to distinguish from the lithofacies characteristics alone (e.g. the various Plinian categories). Usefully, the different eruption types are displayed spatially on diagrams of fragmentation (% finer than 1 mm) versus dispersal area (km2), and ‘explosiveness’ (degree of fragmentation) versus eruption column height (km). There is a less successful attempt to pre-emptively name some deposits of glaciovolcanic successions as glacio-Surtseyan, glacio-phreatoplinian, etc. However, the authors admit that it is unclear whether there are any discernible distinguishing features other than the glacial environmental context, which would presumably need to be proven separately. Occasionally, a previously-named eruption type is not discussed, e.g. Taalian eruptions. This omission is surprising because Taalian eruptions represent a significant style of volcanism (i.e. phreatomagmatic eruptions, formed by contact between magma and groundwater (Kokelaar, Reference Kokelaar1986)), and clarifying their relationship to Ukinrekian eruptions would be beneficial. The authors also suggest a revision of the long-established classification of Volcanic Explosivity Index (VEI) that had hitherto evolved unsystematically. The revision (identified as VEI* to distinguish it from the older system) is badly needed because of pressure from expanding human habitation and tourism causing increasing encroachment on volcanoes, such that even the smaller eruptive events may pose a considerable risk. Thus, the problematical negative VEI categories that had been proposed for low-intensity eruptions (Houghton et al., Reference Houghton, Swanson, Rausch, Carey, Fagents and Orr2013) can now be avoided. The book also introduces the first classification scheme for ignimbrites based on area versus volume.
Such a large volume is hard to review in depth and would take multiple readings to do it full justice. It is divided into eighteen chapters, many individually running to c. 150-200 pages, and grouped into six sections (Parts A-F; see below). Each chapter is followed by a comprehensive reference list and Part F, composed of three chapters, cumulatively comprises c. 640 pages and could be a book on its own. Every section of the book contains information and source references for multiple examples, hence lecturers shall have little difficulty selecting particular volcanoes and their deposits to illustrate key volcanological principles.
It is worth reiterating the book layout to illustrate its impressive breadth (chapter length (in pages) shown in square brackets):
Part A: Laying the foundation
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1. Introductory concepts [33]
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2. Properties of magmas [37]
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3. Influence of environment on magma properties, eruption processes, and deposits [39]
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4. Fragmentation processes in magmas and volcanic rocks [113]
Part B: Effusive eruptions, lavas and sub-volcanic intrusions
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5. Basaltic and other low-viscosity lavas [81]
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6. High-viscosity silicic lavas (rhyolite, dacite, and andesite) [79]
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7. Komatiite lavas and intrusions [45]
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8. Subvolcanic intrusions [81]
Part C: Explosive eruptions, processes and pyroclastic deposits
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9. Explosive eruption styles, columns, and pyroclastic fallout deposits [173]
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10. Subaerial pyroclastic density currents (pyroclastic flows and surges) [197]
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11. Subaqueous flows of pyroclastic debris and their deposits [93]
Part D: Secondary processes in volcanic settings
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12. Surface sedimentary (epiclastic) processes and deposits in volcanic environments [93]
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13. Syn- to post-emplacement alteration processes [41]
Part E: Terminology and approaches to understanding the geology of volcanoes
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14. Terminology for volcanic deposits and rocks [39]
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15. Documenting the geology of volcanoes and volcanic terrains [77]
Part F: Bringing everything together: The big picture
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16. The geology of volcanoes and their facies models [187]
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17. Volcanism and tectonic setting [163]
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18. Volcanic-hosted resources [291]
The products of magmatic explosive eruptions, described in Part C, are represented by three of the longest chapters. For this reader, there is an imbalance relative to the treatment of explosive hydrovolcanic eruptions, which might have been expanded somewhat. More information on cooling joint sets in lavas and their interpretation, particularly in a hydrovolcanic (including glaciovolcanic) context, would also have been welcome. A summary chart showing the criteria by which subaerially erupted and deposited lithofacies can be distinguished from subaqueously transported and deposited lithofacies (e.g. in a tuff cone) would also be useful, particularly for geologists interested in documenting eruptive palaeoenvironments and landscape development over time. This is important because hydrovolcanic eruptions have distinct hazards and deposit characteristics that warrant more in-depth coverage, and identifying past eruptive environments is an expanding area of interest helping us to understand global change. Komatiites and kimberlites also get what feels like an unusually large amount of attention despite their scarcity worldwide, although the association of kimberlites with diamonds may be an understandable driving factor. The final section (Part F) also introduces the reader to plate tectonic concepts and volcanic-hosted mineralization. That section shall probably be of greatest use to geologists in the minerals industry and those working in Archaean terrains, but it is of value to earth scientists regardless of their field of expertise. While the section on terminology presents a particular approach that may not resonate with all geologists, it is a well-structured attempt to address the challenges of consistent nomenclature in volcanology, a notoriously difficult area. Following its introduction by Cas and Wright (Reference Cas and Wright1987), the authors continue to promote a system of naming deposits initially using epiclastic terminology, which they regard as nongenetic (i.e. descriptive and non-interpretive of origin), a stance contested by some (e.g. White and Houghton, Reference White and Houghton2006). Following various discriminatory procedures (e.g. determining the vesicularity and shapes of the juvenile components), genetic names are ultimately assigned. No mention is made of alternative extant and widely used volcaniclastic terminology schemes, however, such as that by White and Houghton (Reference White and Houghton2006). Table 14.1 is a useful summary of nongenetic names for lithofacies, their essential characteristics and origins, but a triangular ash – lapilli – blocks/bombs diagram, similar to those used in sedimentary petrology, showing fields for tuffs, lapilli tuffs, tuff breccias, etc., would have been a valuable addition for completeness. The provision of coloured flow charts to use in the field to help establish a nongenetic terminology is very useful, as is the visual comparator diagram to help make estimates of relative abundances (e.g. of vesicles or phenocrysts). However, most of the examples of full nongenetic names provided are very cumbersome. For example: ‘serpentine-carbonate altered, moderately sorted, moderately crystal-rich, olivine, cored pelletal lapilli, grain-supported, kimberlitic, coarse sand-size packstone’ is lengthy and difficult to use in routine discussion, highlighting the need for abbreviation. The primary use for nongenetic terminology is during fieldwork, when genetic names are inappropriate unless there is unambiguous evidence of a volcanic origin (usually only seen in active or otherwise very young (mainly Quaternary) volcanic settings). However, in the publication(s) resulting from the fieldwork, I suggest that genetic names should be used to label the different deposits from the outset, since the rationale for the names will also be explained in the paper. This will avoid any confusion from double-naming of lithofacies, i.e. initially using epiclastic names and later using volcanic terminology. So there is no need to call a deposit by an epiclastic name (e.g. a gravelly volcanic sandstone) when, from a summation of the research, it is really a lapilli tuff. Simply call it a lapilli tuff from the outset and show the evidence in the description and interpretation.
Although there are good descriptions of the formation of pāhoehoe and ‘a‘ā lavas, a similar treatment of block lava is surprisingly omitted. The book also only briefly mentions the recognized word for volcano – ice interactions, i.e. glaciovolcanism (miss-spelled as glacio-volcanism). Instead ‘subglacial’ and ‘intraglacial’ are used as synonyms in preference, but are less used by the glaciovolcanic community. The sections on facies models for volcanoes and reconstructing palaeoclimatic settings also omit glaciovolcanic edifices, despite their distinctive facies associations, e.g. abundance of lava-fed deltas, minimal pyroclastic lithofacies and association with products of immense outburst-flood events (jökulhlaups). Given the increasing importance of understanding volcano–ice interactions in a changing climate, referencing key reference texts like Smellie and Edwards (Reference Smellie and Edwards2016) would enhance the book’s relevance.
The only significant typo that I noted was the use of ‘tinda’ instead of tindar (one of the most distinctive glaciovolcanic landforms). An additional minor correction for the next edition of this invaluable reference textbook: the youngest lamproites are actually at Gaussberg (Antarctica; c. 56 ka; Tingey et al., Reference Tingey, MacDougall and Gleadow1983), a small nunatak which is constructed of subglacially emplaced pillow lava. Some text citations for publications are also missing from the reference lists, but are not many. This is usually (only?) text references that are not highlighted in blue, so it is presumably an issue of poor copy-editing by the publisher. Additionally, many of the hot links to web sites do not work. However, the number of criticisms that can be levelled at this volume is vanishingly small and it shall remain a benchmark for decades to come. Every volcanologist and many other earth scientists should have it.