Geology news

The Grand Bahamas Bank

At hgttp://geology.com/nasa/great-bahamas-bank/ .... there is a NASA image of the Great Bahama Bank as seen from space. It stretches from near the N American land mass to the south, almost reaching Cuba. The image was taken by the MODIS instrument, a spectroradiometer, from a satellite and picks out beautifully the Bahamas Bank system (see below) which is just 33 feet average depth as opposed to its surrounding waters, or deep water channels, that are thousands of feet deep.

The Drying up of the Sahara

At www.physorg.com/print212152097.html ... a study of lake sediments from a dried up lake in northern Chad in the Sahara has shown evidence that the lake was dessicated by a slow process and progressively, beginning in around 6000 years ago (4000BC) and reaching the present condition around AD900. Geochemical and the analysis of sediments were done on a yearly basis to determine when the Sahara went dry.

Ice Ages

The New York Times (see www.nytimes.com/2010/12/18/world/middleeast/18deadsea.html ) has picked up on the story of the Dead Sea sediment cores that are currently being drilled out of the middle of what is the world's deepest inland basin. The first bore hole is thought to have passed through four Ice Ages, some 400,000 years. The cores will be sent to Germany for analysis so the above date is a bit of guesswork.

A Deep Sea waterway

At http://geology.com/noaa/sulawesi-sea/ .... this is an interesting piece of reseach as the Sulwesi Sea even during the Ice Age was a water-way and a barrier between Sunda Land, the part of Indonesia to the west that was joined up with SE Asia, and the large landmass that comprised Australia (somewhat larger than it is now) and New Guinea - and possibly the Solomon Islands too.

Mars - spreading volcano

At http://specialpaper.gsapubs.org/content/470/115.abstract 'Is Tharsis, Mars, a spreading volcano?' - it is thought Tharsis Rise on Mars is spreading outwards and that has produced rifting at the summit with radial tear-fault systems associated with folding round its periphery. It is said by this geological attempt at understanding the feature to be analogous to a terrestrial mid-ocean ridge - without the corresponding subduction zones.

Prehistoric Footprints at Formby

The footprints are said to date back some 5000 to 6000 years ago, see www.archnews.co.uk/world-archaeology/uk-archaeology/4216-prehistoric-human-footprints.html and it seems a lot of amateurs have been scouring through sand dunes near Formby in Lancashire after the disovery of footprints. According to marine scientists the beaches are receding and this disperses sand and sediment and uncovers underlying layers.

Australian fire history

A paper in Quaternary Science Review (see www.physorg.com/print210875954.html ) claims Aborigines were not responsible for landscape fires and other environmental impacts shortly after their arrival, assumed to be around 50,000 years ago - but in  reality, an unknown. On long timescales fire activity in Australia reflects prevailing climate - less during cold glacial periods and greater activity in warmer phases.

Rivers cut notches in glacial valleys

Again, can be found at www.physorg.com/print210777849.html ... a geological conumdrum as rivers form steep inner gorges in some broad glacial valleys in the Alps. The U shaped valleys were formed by slow moving glaciers, eroding the bedrock over hundreds and thousands of years. When the glaciers receded rivers carved V shaped notches, or inner gorges, into the flow of the glacial valleys.

Evidence of biomass burning in ice cores

At www.physorg.com/print210529446.html there is a press release on a paper from the December 2nd issue of Science and it seems that Antarctic ice cores have found some striking evidence of biomass burning in the southern hemisphere over the last 650 years - with a series of peaks and troughs. They go back to 1350AD and therefore embrace the period of the Black Death epidemic (see Mike Baillie, New Light on the Black Death).

Fossils of the Soom Shale deposit

At www.geology.com/press-release/soom-shale/ ... a site near Table Mountain in South Africa has a rock layer a few metres thick that contains the petrified remains of bizarre early life-forms complete with eyes, guts, and muscles. It is a mystery how they were preserved in such a pristine condition but a paper in the December issue of Geology claims it was all down to the wind. A bitter wind blowing off an ice sheet.