Geological aspects of my X-mas tree

My daughter and I decorated the family X-mas tree a few days ago. A little earlier than usual, but I guess we are both eager for X-mas to start, each in our own way. She is longing for the X-mas presents and I am in need of some holidays ūüôā

Our X-mas tree this year is an Abies nordmanniana (Steven) Spach, one very much like the one on the photo below.

Abies nordmanniana
 
As a palaeontologist specialized in the Late Palaeozoic to Early Mesozoic I would of course have loved a Wollemia nobilis or the Wollemi pine as a X-mas tree, but it is on the endangered species list. The Wollemi pine, which probably evolved in the Early Cretaceous, some 110 million years ago, is an araucariacean conifer that was believed extinct until it was discovered growing in some remote sandstone gorges some 150 km northwest of Sydney, Australia.
 
But Abies nordmanniana is not on the endagered species list, and so it is a much better choice for a X-mas tree. It is native to the Caucasus, Armenia and areas around the Black Sea. Abies nordmanniana probably evolved from an ancestral Mediterranean form during the Pliocene, i.e. between2.6 and 5.3 million years ago (Linares, 2011). Hence, geologically speaking my X-mas tree is a fairly young species.
 
I have never worked with the Pliocene, but it was an interesting time period. Due to a combination of global cooling and drying  grasslands and savannas spread enormously during the Pliocene, creating new environments where long-legged grazing mammals, the ancestors of e.g. zebras and antilopes, could evolve. During the Pliocene North and South America connected through the Panamanian land-bridge, and allowed interchange of species between two continents that had been separated for a long time. This eventually lead to the extinction of most of the South American marsupials and native ungulates. So in fact, the Pliocene was quite a dramatic period.
 
Anyhow, my Abies nordmanniana looks lovely with its X-mas decorations¬†ūüôā
 
Merry Christmas!
 
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Upcoming GTS 2012 presents major changes in the Triassic

Last week I participated in the FORCE meeting “Applications of biostratigraphy to the Norwegian Continental Shelf” in Stavanger, Norway. Besides many other interesting biostratigraphic talks, Felix Gradstein presented the upcoming 2012 edition of the Geologic Time Scale (GTS)¬†(FORCE meeting abstracts, Gradstein et al.,¬†page 6).

Compared to the last GTS2004 there will be some remarkable changes, especially concerning the Triassic, where the ages of four Middle to Upper Triassic stages have changed between 6 and 12 million years.

The new GTS2012 will be published by Elsevier in mid 2012.

Katla is rumbling

Iceland’s biggest volcano, Katla, is rumbling.¬†During the last month¬†there have been more than 500 tremours in and around the caldera. Reaching 1512 m a.s.l. the 10 km wide caldera poses a more severe threat¬†than the¬†recent eruptions¬†of¬†Grimsv√∂tn (May 2011) and Eyjafjallaj√∂kull (March 2010), where especially the latter caused major disruptions in the air traffic over northern Europe.¬†

The caldera is partly capped by a glacier. If Katla erupts melting glacier ice could cause flash mudflows. Volcanic ash from Katla also have the potential of reaching higher up in the atmosphere, casing devastation not only on Iceland.

In 1783 the Laki fissure eruptions, located within the same volcanic zone as Katla, erupted continuously for 8 months. A minor version of the floodbasalt volcanism typical of large igneous provinces, the Laki fissure released huge amounts of ash, hydroflouric acid and sulfuric acid (Stephenson et al., 2003), causing massive destruction on Iceland, where every fifth islander and half of the livestock were killed.

The Laki volcanic fissure on Iceland. Original photo on http:// marsoweb.nas.nasa.gov/ HiRISE/science_themes/volcanology.html

But the devastation reached farther than that. A sulfuric ash cloud from the eruption was distributed over the northern Hemisphere. Historical records from France and England report severe health issues for both people and animals, as well as misgrowth of crops and fruit. In the aftermath of the atmospheric pollution from the Laki eruptions, colder climate and increased mortality plagued Europe for a decade (Grattan, 2005).

Historical records show that Katla usually erupts every 40-80 years. The last major eruption was in 1918. Volcanologists are worried because they are not sure what to expect. Volcanoes are unpredictable and the impact of an eruption depends largely on its size, volume, ash composition and climatic conditions.

 Read more on Sky news and BBC news