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Glaciovolcanism on Earth & Mars

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This delightful monograph provides an excellent introduction to the hitherto neglected topic of how volcanic eruptions interact with the cryosphere.   The distinctive properties of extensive volcanic deposits were first recognised in Iceland as having occurred during past glaciations.   Since then there has been a growing realization of the particularly dangerous hazards produced by magma coming into contact with ice and meltwater, and enhanced production of fine volcanic ash.  

Glaciovolcanism played a significant part in the eruptions of Mount St Helens, and melting magnified an otherwise small Andean eruption by producing deadly lahars in 1985 which flowed down from the Nevado del Ruiz killing more than 24,000 people in Columbia.

Following a brief introduction, this well-structured account with numerous photographs, figures, graphs and tabulations, starts with a round-up of main provinces, with mostly Quaternary examples - though, Kerguelen and Spitsbergen are easily omitted, and it is inconceivable that many eruptions in France did not occur in the vicinity of ice.   Indeed, even in the Eifel maars were probably erupted though permafrost:  any tentative evidence may simply have been overlooked, as this possibility only occurred to me reading the chapter about Mars with references to rootless cones (p.367).   Eruptions are outlined for fourteen historically observed volcanoes, including Eyja, whose volcanic ash grounded flights during the 2010 Easter holidays, though (unlike the Icelandic topographic survey), Eyjafjallajökull, the name given to its glacier, is used following the literature!  

The technical chapters start with physical properties and chemistry, including how varying silica and volatile content affect the temperature and viscosity of lavas.   Physics includes more complex thermal equations (including (6.6) a very rare error confusing gravity with the gravitational constant), fragmentation processes and modes of emplacement.  Next, analytical methods are outlined, then landforms associated with glacial environments, before a handy guide to the formal terminology for describing glaciovolcanic sequences.   This is backed up by three compositionally themed chapters describing typical volcanic products formed under glacial conditions, including ice-impounded lavas.   The chapter on hazards expands on earlier examples.   Throughout the text is extremely well illustrated, even if the middle pages containing 25 high quality colour versions don't need captions stating that they also appear in black and white.  This is in stark contrast to some of the pages, which are incredibly faintly printed for such an expensive volume.

The penultimate chapter on Mars benefits most from its colour illustrations, as it briefly outlines how low surface gravity of 3·71 ms-2 and atmospheric pressure probably influenced past eruptions.  This is coupled to a very high obliquity with past axial tilts approaching 47° compared to 25° currently, which means Martian glacial periods are the opposite to ours with higher polar insolation and warmer climates than usual.   The final chapter sets out how future research might be enhanced in a number of avenues, including the timing of eruptions in relation to the glacial cycle and likely responses to climate change, plus selecting Martian landing sites which may have harboured extra-terrestrial life sustained by volcanic geothermal heat.   

Reviewed by David Nowell 

References

  • Kortiđ er Prentađ á Íslandi 2009.   Landmannalaugar – Þórsmörk – Fjallabak   1:100,000 sérkort / sheet 4  Icelandic series.  See notes on reverse to deduce that the root of the volcano’s name is Eyja  
  • Nowell, D.A.G., Jones, M.C. and Pyle D.M. 2006.  Episodic Quaternary volcanism in France and Germany.   Journal of Quaternary Science, Vol. 21 (6) 645-675

GLACIOVOLCANISM ON EARTH AND MARS - PRODUCTS, PROCESSES AND PALAEOENVIRONMENTAL SIGNIFICANCE by J L SMELLIE AND B R EDWARDS Published by:  Cambridge University Press 2016. ISBN:  978-1-107-03739-7 List Price £112, $140 xii + 483pp Hardback W: www.Cambridge.org