When Antarctica went into the deep freeze 19 May 2008 A member of the team looking at the top layer of sediment, deciding where best to sample to get different time intervals. Bringing up a core of mud from 34 million years ago After the core is brought up it is laid out for scientists to describe and take samples. Extreme close up of the 35 million year old foram: Cribrohantkenina inflata. discovered in the cores from Tanzania. More images of these intricate forams can be seen in the 'Up close with Nature' gallery. Scientists from Amgueddfa Cymru – National Museum Wales and Cardiff University have found new evidence of past climate change, which helps solve some of the mystery surrounding the appearance of the vast ice-sheet in Antarctica 34 million years ago. Antarctica hasn't always been covered with ice – the continent lay over the south pole without freezing over for almost 100 million years. Then, about 34 million years ago, a dramatic shift in climate happened at the boundary between the Eocene and Oligocene epochs. The warm greenhouse climate, stable since the extinction of the dinosaurs, became dramatically colder, creating an "ice-house" at the poles that has continued to the present day. Global cooling Many climate scientists are involved in trying to figure out what caused this climate shift. This should tell us more about how the climate responds to major controls like changes in the Earth's orbit around the sun, and the concentration of greenhouse gases in the atmosphere. Past climate changes can be recorded by studying tiny microfossils in layers of deep sea mud. Up until now, scientists found that the oceans appear to have warmed up during this big climatic shift. Their studies suggested that warming seemed to coincide with ice-sheets appearing in both Antarctica and the Arctic. This conflicting evidence, of warming seas while ice-sheets grew, doesn't fit in with computer simulations of the climate at the time; the computer models don't show ice to be present in the Arctic." Tanzania drilling project The solution to this icy puzzle has come from a surprising place – Tanzania in East Africa. The Tanzania Drilling Project team, including scientists from Amgueddfa Cymru and Cardiff University, have been recovering cores of ancient mud deposited on the seafloor millions of years ago (which has since been geologically uplifted into land). The Tanzanian cores are special because large thicknesses of mud were laid down over a relatively short time, meaning that climate changes through time are seen in great detail. Also, beautifully preserved microfossils are found in the cores. The Tanzanian cores provide the first really clear picture of how sea-level fall fits in with the climate shift. Setting the record straight The chemistry of the Tanzanian microfossils has been used to construct records of temperature and ice volume over the interval of the big climate switch. These new records show that the world's oceans did cool as the ice-sheets appeared, and that the volume of ice would have fitted onto Antarctica. So the computer simulations of climate and the past climate data now match up. The focus now is to look for evidence of the ultimate cause of this global cooling. The prime suspect is a gradual reduction of CO2 in the atmosphere, combined with a 'trigger' time when Earth's orbit around the sun made Antarctic summers cold enough for ice to remain frozen all year round. How it works The shell chemistry of pin-head sized animals called forams can tell us how ocean temperatures changed through time. Forams are great tools for studying climates of the past, which helps us learn about the uncertainties of our future greenhouse climate. 1). Forams take chemical elements from the ocean into their shells, using more magnesium at warmer temperatures. 2). Dead forams fall to the sea floor and build up in layers of mud over millions of years. 3). Today, going down through the mud layers is like going back in time. If we can measure the magnesium content of forams going down through the mud, it gives us a record of how ocean temperature changed through time - more magnesium equals warmer temperature. Further Reading Lear, CH, Bailey, TR, Pearson, PN, Coxall, HK, Rosenthal, Y. Cooling and ice growth across the Eocene-Oligocene transition. Geology 36 (3), 251�254. 2008. http://www.gsajournals.org/perlserv/?request=get-abstract&doi=10.1130%2FG24584A.1
The decorated floor tiles from Raglan Castle 6 September 2007 Raglan Castle. The castle's fortifications, including the Great Tower shown at the centre of this view, were established in the 15th century. Image: Cadw (Crown copyright). Late 13th to early 14th-century tile of the Wessex School from the chapel at Raglan. 15th-century Malvern-school tile used at Raglan. 16th-century maiolica tile from the chapel floor laid by Earl William, probably before 1572. Reconstruction of life at Raglan Castle in the 16th century, at the time of the Third Earl of Worcester. Image: Cadw (Crown copyright). Three centuries of fashion and design can be seen in a collection of decorated floor tiles found during building works at Raglan Castle in 1947. In 1549 William Somerset (1526-1589) succeeded to his father's position as third Earl of Worcester and owner of Raglan Castle. From this base in south-east Wales he launched a career that was to see him thrive at the courts of Edward VI (1547-53), Mary (1553-58) and then Elizabeth I (1558-1603). He is buried in Raglan parish church. Such a prominent figure lived a lifestyle that suited his high social standing, and we can see this aspiration in the extensive remodelling that he undertook of the fortress-mansion he had inherited. He set about an extensive programme of modernisation that affected all parts of the castle and its grounds: the hall and accommodation were improved, kitchen and service areas upgraded, a long gallery was introduced and gardens created in Renaissance style. The Castle's furnishings were also updated with items that reflected contemporary European fashion. This is illustrated in the chapel at Raglan. Raglan Chapel The chapel at Raglan dates from at least the 13th century. It had a floor of thick red earthenware tiles with decoration inlaid into its surface using a contrasting colour. Such two-colour tiles often had designs of shields and monograms, over which a clear glaze would be fired. These tiles were the height of fashion in the mid-14th century. About 1460, these tiles were replaced with two-colour tiles of bright yellows and golden browns. This must have provided a rich backcloth for the treasures of the chapel. However, these designs were not to the taste of Earl William. He preferred the fashionable products of the Spanish Netherlands, and used his considerable wealth to purchase tin-glazed earthenware tiles painted in a polychrome style that was popular in the Renaissance period. The result was a dramatic transformation of the chapel, lightening its interior and adding delicacy to its decoration. Sadly, the abandonment of Raglan in the wake of the English Civil War has left few traces of the other changes that Earl William made to the interior furnishings of his castle. We are left instead to speculate on the luxury he must have brought to it, and to reflect on the transient nature of that wealth, surviving as it does in a small collection of painted floor tiles and a handful of other items. Guide to the Tiles Late 13th- to early 14th-century tile of the Wessex School from the chapel at Raglan. It shows two birds feeding from a central tree. Tiles with this design were also used at nearby Tintern Abbey and White Castle. 15th-century Malvern-school tile used at Raglan. The Latin text reads 'May the peace of Christ be amongst us always. Amen'. 16th-century maiolica tile from the chapel floor laid by Earl William, probably before 1572. These tiles were probably imported from the Spanish Netherlands, perhaps Antwerp, where maiolica production had been established in the early 16th century. Background Reading Raglan Castle by J. R. Kenyon. Cadw (2003). 'The chapel at Raglan Castle and its paving tiles' by J. M. Lewis. In Castles in Wales and the Marches by J. R. Kenyon and R. Avent, pp.143-60. University of Wales Press (1987). The medieval tiles of Wales by J. M. Lewis. Amgueddfa Cymru (1999).
Wooden crucifix originally sparkled with gold 4 September 2007 The crucifix figure from Kenys Inferiour, Monmouthshire Detail of the head of the crucifix figure. Detail of the torso and loin-cloth in UV light. Detail of the torso and loin-cloth in reflected light. Scientific examination of a crucifix of the Middle Ages from Kemeys Inferior, south Wales reveals that the wooden object seen today was once richly decorated in vibrant colours and magnificent gold leaf. In 1850, the remains of a carved wooden figure of Christ were discovered in the church of Kemeys Inferior, a few kilometres east of Caerleon, south Wales. An object of exceptional importance Before the Reformation of the 16th century (when England and Wales officially turned from being a Catholic nation to a Protestant one), such figures of Christ were common throughout England and Wales and the Kemeys Christ is the most complete example of only a handful of medieval fragments to survive in Britain, and so is of exceptional importance. Fragments of the Kemeys Inferior figure were found, 'together with skulls and bones', in 'the blocked up rood-staircase' during repairs and alterations to the church in about 1886. It was transferred in 1930 to Amgueddfa Cymru. Although the figure was thought to be from the 14th century, arguments supporting this have never been set out in detail. Dating the figure relies on comparing other sculptures, and it is now thought to be from the late 13th century. Made in Wales Owing to the rarity of surviving figures in Britain from this period it is necessary to study objects from the continent for further clues. For example, late 13th-century crucifix figures from Sweden share several similar characteristics, whereas the 14th-century Christ from Mochdre, Denbighshire, the only comparable wooden figure from Wales, is quite different. The Kemeys Christ was more than likely to have been made in England or Wales. Investigation and analysis of the crucifix Very little of the colour that once covered the wooden figure can be seen today, but routine work done by Amgueddfa Cymru in 1999 led to in-depth investigation of the surface of the object. The figure was X-rayed and viewed under ultra violet (UV) and infra-red (IR) light before being examined under the microscope. This revealed the original colour scheme, with differences between the torso and the arms, previously considered to have been later additions. Vivid and rich colours In contrast to its present condition, the Kemeys Christ originally boasted a vivid and richly coloured appearance as was popular throughout the Middle Ages. Great care was taken in decorating the figure. When new, it would have shone with gold leaf. Examination of the figure has revealed considerable evidence of polychromy (use of many colours), and, like other examples of medieval sculpture, over-painting. Although little colour survives on the arms, the right arm does have two layers, which may suggest replacement of the left arm either during the first half of the 16th century or even earlier. At least three layers of painting have been detected, though the dating of each is problematic. The secondary colour scheme appears to have included gilding on the hair; gold, red and blue on the inside of the loin-cloth; dark brown and black details on the face; a green crown of thorns; and flesh tones in pale pink, with red emphasising the wounds. Stunning polychrome work like this would have been standard on such an important sculpture. The Kemeys figure clearly represents Christ on the cross, who is portrayed alive, with his eyes still open. The Kemeys Christ is a rare survival of pre-Reformation devotional figures once common in the British Isles. With the original height of about 94 cm, this powerful image of Christ's suffering would have been widely seen and prayed to, and formed a purposeful part of everyday life.
Dinosaur relatives swam in south Wales 26 July 2007 Amgueddfa Cymru holds fine specimens of prehistoric marine animals, related to the dinosaurs, that swam off the coast of south Wales. Specimens from Dorset illustrate how, once, an ancient sea linked the two areas. Reconstruction of an ichthyosaur chasing its squid-like prey Tropical Wales About 210 million years ago the small part of the Earth's crust that is now Wales lay well to the south of its present latitude, probably close to the northern tropics, where the land formed part of a huge supercontinent called Pangaea. Our climate was hot and humid, with much of Wales comprising barren uplands surrounded by desert-like mudflats. To the south, and spreading far across into Europe, was a series of large lakes. Wales drowns As the continents drifted northwards the crust broke up and at various times the seas rose and spread across the land. With these spreading seas came new marine animals that we now see fossilised in the rock record. Some of the most beautiful and spectacular are the marine reptiles known as ichthyosaurs (literally, 'fish lizards'), which were distant cousins of the land-living dinosaurs. By 200 million years ago, early in the Jurassic Period of geological time, the sea covered southernmost Wales. On the sea-floor, a blanket of fine lime sands and muds was deposited, which have since been compacted into the horizontally bedded mudstones and limestones forming the familiar cliffs in the Lavernock area and extending westwards from Barry to Southerndown. Abundant fossils Ichthyosaur remains are not uncommon in these rocks, although they are mostly found as isolated teeth and bones. The fragmentation took place following the death of the animals, when the skeletons were broken up by currents and wave action. Only rarely have more complete specimens been found in south Wales. In contrast, rocks of the same age in Somerset and Dorset have long been known as a rich source of complete or almost complete ichthyosaur skeletons. The early Jurassic sea extended from the shoreline area of southern Wales across south-west England and beyond to central Europe. In the progressively offshore, deeper-water areas to the south, wave action and coastal currents were weaker, so skeletons were more likely to sink to the sea floor and remain more or less intact. Even so, such skeletons are still found only comparatively rarely today, so we are very lucky to have several almost complete ichthyosaurs in our collections from Lyme Regis in Dorset. Some of the most impressive are on display in the exhibition Evolution of Wales at National Museum Cardiff. The fact that 200 million years ago the sea was continuous from south Wales across to Dorset means that we can use these beautiful fossils to illustrate part of the history of our area. The Dorset fossils are the same species as those found in the Glamorgan cliffs, and the animals would have been swimming freely between the two regions. The specimens on display show beautifully the streamlined, dolphin-like shape of the ichthyosaurs. They were adapted superbly for rapid swimming, with propulsion by a large, vertical tail and steering with four flipper-like paddles. Their diet probably consisted mostly of fish and squid.
460-million-year-old relatives from Wales and Belgium reunited 26 July 2007 Didymograptus, a 'tuning-fork' graptolite of the kind found commonly in both areas. Pricyclopyge, a large-eyed pelagic trilobite that is widespread in Britain and northwest Europe. Headshield of Ormathops, a benthic trilobite endemic to Bohemia. Llanvirn Farm, Abereiddy, Pembrokeshire In the late 19th century, Henry Hicks, a surgeon from St David's, took up an interest in the ancient rocks of north Pembrokeshire. In 1881, he named the rocks at Abereiddi Bay the "Llanvirn Group", after a nearby farm. Today, this name is internationally recognized and is found in geological publications all over the world - fame indeed for a small farm on the windswept Pembrokeshire coast. Staff at Amgueddfa Cymru have been studying Llanvirn rocks and their fossils for over thirty years. In 2000, Dr R Owens of the Department of Geology was invited to examine fossils from rocks of the Llanvirn Series that are exposed in the Meuse valley in Belgium. Trilobite species found in these rocks were compared to those from the British Isles. Identical fossils from Wales and Belgium Fossils in Llanvirn rocks tend to be difficult to find without a good deal of time and effort. The graptolites and trilobites discovered in Belgium are all identical with those found in Wales and the Lake District. The Llanvirn rocks in which the fossils occur are understood to have been laid down in the deep ocean. During the Ordovician period when Llanvirn rocks were deposited, southern Britain, Belgium and northern Germany were all part of a small continent named Avalonia, separated from the vast continent of Gondwana by the Rheic Ocean. Blind trilobites Trilobites that are thought to have lived only on the sea floor (benthic species) tend to be confined to specific areas, but those thought to have swam the ocean waters (pelagic species) are widely distributed. One of the trilobite species found in Belgium has enormous eyes and is thought to be pelagic. This fossil is common in many areas. By contrast, another one, described originally by Hicks from Abereiddi, is blind, and is thought to have been benthic. However, it also has a wide distribution, which in this case is more difficult to explain. It could have spent a long time as a small larva, allowing it to drift around and causing a wider distribution of the fossils; alternatively it might have been pelagic, living in and around floating masses of seaweed. Ordovician rocks that are younger than those of the Llanvirn Series also crop out in the Meuse valley and these contain trilobite species that are also found in north Wales and northern England. These show that throughout the Ordovician Period, Belgium remained part of Avalonia. However, rocks that occur between these and the earlier Llanvirn rocks contain trilobites unlike those from Britain, but which closely resemble fossils from Bohemia. It is unlikely that part of Avalonia split away, moved closer to Bohemia and then merged back again. So why the similarity of these trilobites to those of Bohemia? The answer could lie in the underwater environment becoming more similar to that of Bohemia than to southern Britain. Although the relative longitudes of Bohemia and Avalonia are unknown, the distance separating the two areas must have been sufficiently close to allow the trilobite larvae to cross between the two and become widely distributed. The outcome of this work has been to confirm close fossil links across parts of Pembrokeshire and Belgium 460 million years ago, but also to highlight problems of fossil distribution that have yet to be fully resolved.
