Monday, 29 March 2010

Witnessing the Birth of a New Ocean - April 1st

No, this is not an April Fools' joke, it is the title of the lecture to be given at 7.30 at the BRLSI, 16 Queen Square, Bath by Dr. Thierry Menand from University of Bristol. Further details can be found on the Bath Geological Society website.
Everyone is welcome - visitors £4.00 - free refreshments.

Thursday, 18 March 2010

Hydrogen sulfide emissions along the Namibian coast

Hydrogen sulfide erupted along the coast of Namibia in mid-March 2010. Pale-hued waters along the shore hinted at gaseous rumblings as the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite passed overhead and captured this true-color image on March 13, 2010. Although ocean water appears navy blue farther from shore, water along the coast ranges in colour from peacock green to off-white. Ocean water wells up in this area along the continental shelf. The milky surface waters that coincide with gaseous eruptions along Namibia’s coast have a low oxygen content. As reported in a 2009 study, the frequent hydrogen sulfide emissions in this area result form a combination of factors: ocean-current delivery of oxygen-poor water from the north, oxygen-depleting demands of biological and chemical processes in the local water column, and carbon-rich organic sediments under the water column.
Commercially important fish species have hatching grounds along the Namibian coast, and hydrogen sulfide eruptions can often kill large numbers of fish. In addition, the gas eruptions send a noxious rotten-egg smell inland. These events bring some benefits, however. Sea birds eat the fish carcasses, and humans can make meals of lobsters fleeing onshore to escape the oxygen-deprived waters.
Inland, this MODIS image shows the rippling sand dunes of the Namib Desert, which stretches for hundreds of kilometers along the southern African coast.

Monday, 15 March 2010

27th March - Charterhouse & Burrington Combe

Do join us on Saturday 27th March for this excellent field trip to the Mendip Hills to be led by Dr. Peter Hardy.
Field trip assembly point is at the roadside at the stile into Ubley Warren, ST 504 554 at 10.30 a.m.
Further details about car parking and for the day can be found on the Bath Geological Society website.
At Charterhouse we shall observe the relationship between the land-forms and the geology, especially the three main rock types, i.e. Devonian clastic sediments, Lower Carboniferous shales and limestones. The additional feature which is well seen here is the site of extraction of lead ore over the past two millennia, dating back at least to the Roman occupation of Britain, and the more recent evidence for local smelting of lead from the mineral veins.
At Burrington we shall examine in greater detail the lithologies and fossil content of the above-mentioned sediments, especially those of the limestones, but also a little of the shales. Loose specimens of the Devonian sandstone are also present in the lowest parts of the combe, and in addition we shall see sedimentary deposits from the Palaeozoic/Mesozoic transition of the Triassic sequence, represented here by coarse conglomerates which rest on an early valley floor formed when the combe was a desert wadi on the slopes of the newly elevated hills.
Everyone is welcome - visitors £2.00.
(The photo is from the British Geological Survey - click here for more details)

Friday, 5 March 2010

Geoconservation in Gloucestershire - 17th March

The Geology section of Bristol Naturalists' invites you to ‘Geoconservation in Gloucestershire' by David Owen (Gloucestershire Geology Trust)
David (who was the leader of a very enjoyable Bath GS walk in the Southern Malverns, last summer) will tell us about the work of the Gloucestershire Geology Trust (formerly Gloucestershire RIGS Group).
Wednesday 17 March, 19:30, SH Reynolds Lecture Theatre, Wills Building, Queens Road, Bristol. Everyone welcome.

Tuesday, 2 March 2010