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5 Posts tagged with the earth_sciences tag




On the nature & causes of volcanism in the Galápagos archipelago


Tuesday 21st May - 4.00 pm - Mineralogy seminar room


Dr Sally A Gibson, Department of Earth Sciences, University of Cambridge, UK.


Diversity appears to be key to understanding natural phenomena in the Galápagos archipelago. Whilst most associate this with the unusual creatures that inhabit the islands it is also true of their volcanic nature.

Historical perspective: The volcanic nature of Galápagos was based on reports of pirates, buccaneers and naval admirals until 1835, when Charles Darwin visited the archipelago during the Beagle voyage. Although widely regarded as a zoologist, Darwin was first and foremost a geologist and especially interested in the formation of volcanic islands. Whilst in Galápagos, most of his time was spent on James Island (now known as Santiago) and here he made a crucial observation regarding the occurrence of different volcanic rock types; he realised that confinement of low-density trachytes to elevated parts and higher-density basalts to lower slopes of the same volcano meant that different types of magma could form in ‘the body of a volcanic mountain’ by sinking of crystals. In this regard he was the first scientist to link the diversity of volcanic rock types to what we now refer to as crystal settling. Darwin’s theory of crystal sinking was published in 1844 but not widely accepted at the time.


21st Century importance: The Galápagos archipelago is a natural laboratory for Earth Scientists and provides a unique opportunity to test models of mantle melting. It is one of the world’s most volcanically active regions with eruptions of predominantly basaltic lavas occurring every 3 to 5 years. Galápagos is located above a mantle plume and adjacent to an oceanic spreading centre. Whilst the greatest volumes of melt occur in the west of the archipelago, close to the postulated axis of the plume, volcanism is widespread. There are no age-progressive linear relationships between activity and distance from the location of the present-day hotspot and no temporal variation in magma type as there is for example at Hawaii. The large geochemical dataset for recently erupted basalts and high-resolution seismic database allow greater constraints to be imposed on the causes of volcanism than for any other archipelago. Melt generation occurs both in the region of active mantle upwelling, which has a radius of ~100 km, and also where plume mantle is being dispersed laterally towards the adjacent spreading centre. The composition of erupted basalts is closely linked to the thickness of the underlying lithosphere: numerical modelling of geochemical and geophysical datasets has revealed that this is relatively thin (45 km) beneath the NE of the archipelago and allows the generation of tholeiitic basalts. Above the current zone of active plume upwelling the lithosphere is thicker (60 km) such that the amount of melting is lower and alkali basalts are generated. Isla Santiago is located in central Galápagos above the margin of the zone of active upwelling and also on the edge of the zone of thin lithosphere. The island is unique in that it has experienced recent eruptions of basaltic melts with extremely varied major- and trace-element and also isotopic compositions. This diversity is a manifestation of both complex physical processes and compositional variations in the underlying mantle plume.

For additional details on attending this or other seminars see


Tuesday 7th May - 4.00 pm

Mineralogy seminar room


Another point of view on sexual selection in prehistoric animals

Dr Rob Knell, Senior Lecturer at Queen Mary University of London.


Sexual selection is one of the most important driving forces in evolution and is responsible for a tremendous amount of the morphological diversity that we see today. Many of the most charismatic prehistoric animals also appear to carry traits that could be explained as the result of sexual selection: horns, crests, plates, sails and many others. Nonetheless, palaeontologists have traditionally avoided using sexual selection as an explanation for these features and have preferred mechanical, thermoregulatory or species-recognition based interpretations, probably because it is very hard to produce testable hypotheses about the behavioural significance of such traits when we are unable to observe an animal's behaviour. This conservative approach is likely to lead to a significant degree of misinterpretation - sexual selection is a ubiquitous and powerful force and there is no reason to discount it as an explanation for morphological diversity in the fossil record. I will examine the problem of how we can detect sexual selection in the fossil record and discuss issues such as sexual dimorphism, allometry and how it changes with sexual maturity, apparent cost and diversity as potentially helpful indicators of sexually selected features in extinct animals.



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Studying new minerals: the nature and value of novelty - Dr Mark Welch (NHM).  Tuesday 26th March 2013, 1600h, Earth Sciences Seminar Room


The geological history of the Earth over the past 4.5 billion years has seen immense diversity in the physical and chemical conditions in the crust.  In these various conditions, different minerals form and for many years a significant part of Museum research undertaken by the Department of Earth Sciences has been the identification and characterisation of minerals new to science. Characterisation of minerals involves a comprehensive determination of atomic-scale structure, composition and diagnostic physical properties using both traditional techniques and advanced analytical equipment.


Apart from their novelty, new minerals offer the chance to develop models of structural hierarchies in which major building principles are uncovered by relating these minerals to others. Time and again new minerals provide insights into perplexing mineralogical problems that often bear upon wider geological or technological issues, such as the possibilities for effective storage or immobilisation of toxic elements, transformations between environmentally radical and benign minerals, or new directions for preparing new synthetic analogues of technological materials such as nanoporous and microporous catalysts and molecular sieves.


In this talk an outline of the new-mineral research currently undertaken will be given, describing the experimental techniques involved in characterising new minerals. A few examples illustrating how the study of new minerals has provided fertile ground for wider scientific research will be described.


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Fungal-plant associations in Palaeozoic-Mesozoic times

Dr Christine Strullu-Derrien, Department of Earth Sciences, NHM

Thursday 15th November
Neil Chalmers Seminar Room, DC2, NHM 15:00



A fungal mode of life (mycelial growth and mode of nutrition) is shared by several living groups of organisms, notably Fungi (Eumycota) and Oomycetes (Stramenopila). Originally, a lot of these groups were called fungi, but now we know that they have quite diverse relationships among eukaryotes. These organisms are known to have coexisted with plants since the dawn of life on land, but their role in plant evolution is still poorly understood.


Recent research based on historic collections of petrified plants is opening up a rich new source of information for the study of fungal-plant associations. Dr Strullu-Derrien will present an overview of recent findings including fossil evidence for fungi and fungi-like symbionts in Palaeozoic and Mesozoic ecosystems.



For additional details on attending this or other seminars see


One-day meeting sponsored by the QRA, QUAVER, NERC and the NHM

Wednesday 19 September 2012, 10 am – 6 pm

Flett Theatre, Natural History Museum. 


Confirmed speakers:


Tony Stuart (Durham) – Megafaunal extinction and survival, with special reference to northern Eurasia

Adrian Lister (NHM) – Mammoth extinction, refugia, and the synergy of climate and people

John Stewart (Bournemouth) & Chris Stringer (NHM) – Range shifts and extinction of Neanderthals and other human populations in the Late Quaternary

Ian Barnes (Royal Holloway) - Applying ancient DNA to Late Quaternary extinctions

Judy Allen, Yvonne Collingham & Brian Huntley (Durham) – Modelling vegetation change and  Late Quaternary extinctions

Martin Street (Neuwied) – Implications of the Western and Central European Late Upper Palaeolithic archaeological record for Late Quaternary Extinctions

Sam Turvey (ZSL) & Susanne Fritz (Frankfurt)  – The ghosts of mammals past: global patterns of mammalian extinction during the Holocene

Jennifer Crees (Imperial): Large mammal extinctions in Holocene Europe: case closed?

Kenneth Rijsdijk (Amsterdam) & the Dodo Research Programme team - Climate induced mass mortality vs. human induced extinction: an interdisciplinary analysis of a dodo mass grave on Mauritius

Ben Collen, Lucie Bland & Martina Di Fonzo (ZSL) – Wildlife in a changing world: predicting how populations decline to extinction

Kate Jones (UCL) - Current and future extinctions: windows into the past


For full programme details and registration (required), please go to