Geology news

From Dartmoor to the Scillies, one slab of granite

In the 'Sunday Times Book of the Countryside' (1983) there is a very nice diagram of the SW peninsular (Cornwall and Devon). It seems that one giant block of granite rises from a single core, or batholith - which reaches down to an unknown depth below the surface. The upper parts of the granite slab protude from the surface on Dartmoor, Bodmin Moor, the hills around St Austell, Lands End ... and the Isles of Scilly.

Climate Change over thousands of years

This post is informative ... see www.esd.ornl.gov/projects/qen/transit.html 'Sudden Climate transitions during the Quaternary' ... and is about a whole series of rapid climate transitions over the time span of the last few million years. The most detailed information concerns the YD to Holocene temperature change at 9500BC - which happened very quickly. However, the speed of this change is representative of similar but less well documented climate transitions prior to that date.

The short and the long of the Siberian Traps

A new paper has suggested the Siberian Traps caused a long drawn out mass extinction at the Permian/Triassic boundary - described as a 'mass dying event' by some geologists as a result of so many species becoming extinct - to be replaced during the Triassic by new species that appear to have expanded relatively quickly. However, back in November the timeline of the event was much quicker - see http://web.mit.edu/newsoffice/2011/mass-extinction-1118.html where it is said it took place in the blink of an eye in geological time, a mere 20,000 years.

Gibraltar's bottom waters

At www.sciencedaily.com/releases/2012/01/120125113147.htm there is a report on research off the coast of Spain near Gibraltar and in the Gulf of Cadiz where sediment cores were drawn up for study. The Strait of Gibraltar re-opened just 6 million years ago, fairly recent in the geological time-scale. Way down on the bottom off Gibraltar the Mediterranean waters are pouring into the Atlantic like a cascade. As the Mediterranean is more salty than the Atlantic it sinks, plunging 1000 metres downslope and scours the sea floor carving out canyons and building up mountains of mud.

Interesting geology on the sea floor

At www.sciencedaily.com/releases/2012/01/120110114434.htm there is a piece on deep sea vents in the Caribbean - with a difference (published in Nature Communications, January 10th). The vents, or deep sea hot springs we might say, are 5km down in a rift on the Caribbean sea floor. What is novel however is the discovery of 'black smokers', which are vents too, on the upper slope of an undersea mountain which rises 3km from the sea bottom. The mountain formed, it is claimed, when a vast slab of rock was twisted up out of the ocean floor. How did that happen?

The Quasicrystal

A rock from a mineral collection donated to a museum in Florence has an origin in the Koryan mountains in the Kamchatka peninsular. It was recently found to include grains of icosahedrite, a quasicrystalline mineral that was first discovered in a laboratory, according to a paper in PNAS - see www.physorg.com/print245661710.html. It is the inner structure of these minerals that is novel as rather than being clusters of atoms as in ordinary crystals their composition is much more intricate and can form strange shapes such as a 20 sided icosahedron - with the symmetry of a ball.

Do the Plates move around the globe, or is that an illusion?

The actual idea of continental drift has never been accepted - what we have in the consensus theory of Plate Tectonics is something more subtle. In this all the plates move but in different directions and at different speeds, and the plates consist of both continental crust as well as the attached sea floor bottom. In Wegener's theory it was just the continental crust that moved, and Africa, it was said, was formerly joined to South America and NW Europe to Newfoundland and the Appalachians.

New island(s)

We have already seen that an undersea volcano is in the process of creating a new island in the Atlantic - adding it to the Canaries, Now, a new island has emerged in the midst of another group of islands - in the Red Sea (see www.physorg.com/print244271429.html). It was spotted by a NASA camera onboard an orbiting satellite (image included) and this too was formed from volcanic activity on the seabed - off the coast of Yemen.

Canaries volcano and a spaceship at the edge the solar system

The under-sea volcano that has erupted deep on the sea-bed off the Canary island of El Hierro is now just 60m below the surface - and still growing. It will either create a new island in the Atlantic or will become an extension of the southern shore of El Hierro. There is also seismic activity to the north of El Hierro and over the last 4 months there has been some 11,000 tremors across El Hierro itself (see www.bbc.co.uk/news/magazine-15917740)

Bumping the Crust

At www.scientificamerican.com/article.cfm?id=japan-earthquake-moves-seafloor we learn that the Fukushima earthquake moved the sea floor as much as 50m laterally and 16m vertically. In addition, the crust as a whole did not move forwards by 50m but varied between the coastline and the nearby trench (thought to be a subduction zone) which means that closer to the coast it was just a movement of a few feet, and out at sea rising to 20 and 30m and even further out to 50m movement.