Thursday, 9 January 2020

Blobs in the Mantle

Blobs in the Mantle

There are blobs in the mantle. Are they hotter areas or are they a different composition?



Two enormous regions of ultra-hot material sit beneath Africa and the Pacific Ocean.
Olena Shmahalo/Quanta Magazine; source data: Sanne Cottaar


A correspondent has brought THIS ARTICLE to my attention. It discusses the possibilities and describes how they were found. And this gives them their name - Large Low-Shear-Velocity Provinces or LLSVPs. 

The different composition theory seems to be winning at the moment. But is the composition difference due to crystal settling during cooling or are they parts of Theia, the Mars sized body whose impact with the Earth gave rise to the Moon?

Obviously there is a lot still to be settled about these blobs including the affect they have on the Earths surface. Read the article to get some idea of how little we know!

Saturday, 4 January 2020

6th to 12th January 2020


NEXT WEEKS EVENTS

6th to 12th January 2020


THE FOLLOWING IS AN EXTRACT FROM BRISTOL AND WEST COUNTRY GEOLOGY CALENDARS

MORE DETAILS CAN BE FOUND IN THE BRISTOL AND THE WEST COUNTRY CALENDARS AND ON THE WEB SITES OF THE RELEVANT SOCIETY OR ORGANISATION.


MONDAY 6TH



Tuesday 7th



wednesday 8th



thursday 6th



Friday 7th



saturday 8th

South Wales G A - Lecture
When
Saturday, 11 Jan 2020
Where
Venue to be confirmed (map)
Description
Holiday Geology
--------------------------------

DGAG AGM
When
Sat, 11 January, 14:00 – 17:00
Where
Broadmayne Village Hall, Cowleaze Rd, Broadmayne, Dorchester, Dorset, DT2 8EW (map)
Description
Saturday January 11th: DGAG AGM, Broadmayne Village Hall. 2 p.m.-5 p.m. 


sunday 9th




Fertilising the oceans with iron

Fertilising the Oceans with Iron

A correspondent has brought THIS ARTICLE to my attention. He did it for two reasons: 

  1. It is a very interesting article and 
  2. My photograph of Banded Iron Formation which I wrote about some time ago, is used to illustrate it. See HERE.
The first reason is the more important one - of course. 

I didn't realise how complicated the chemistry of iron in the oceans and atmosphere was. Iron is the fourth most abundant element in the Earth's crust but is almost absent in the oceans. Its absence can hinder the growth of diatoms and other beasties. If there was more iron available, more diatoms could form, removing carbon dioxide from the atmosphere. Sounds simple, but it is not. Read the article to understand some of the complications!

Iron-rich dust launched into the air by winds swirls around the Southern Ocean. Understanding how iron’s chemistry shifts during its journey from earth to air to sea will be important for developing better climate models. (William Putnam and Arlindo da Silva, NASA / Goddard Space Flight Center)

Monday, 30 December 2019

DOWN TO EARTH EXTRA - JANUARY 2020


DOWN TO EARTH EXTRA - January 2020


You can get the latest edition HERE.



PROPOSED TWO INDOOR COURSES IN MARCH 2020

Proposed Two Indoor Courses in March 2020

Nick Chidlaw has contacted me about two courses he would like to run in Thornbury in early March.

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-


Information on courses
I am currently offering two 1-day courses for next March; these are indoor-based, and describe field areas where I have organised events in the past. These courses may be attractive to people who are not in a position to visit these areas e.g. insufficient time available because of family / work commitments, or health problems.
Details of each course is provided at the bottom of this message.
Each course would comprise powerpoint-based lectures, together with examination of hand specimens of relevant mineral and rock types, and published geological maps of the field areas. The hand specimens have been collected by the tutor in the field areas described.
A handout outlining the day’s programme containing sketch maps and other relevant drawings, stratigraphic tables and a list of optional reading,  would be provided on each course. No prior knowledge of geology or the study areas would be assumed.  
Please note that these courses are run on the same weekend and in the same venue, but are independent of one another – you can enrol on both if you wish to, or one of them, according to your interests / availability.
Venue for both courses
The Buckingham Room (single storey building by the car park) at The Chantry, 52 Castle Street, Thornbury, South Gloucestershire. BS35 1HB. See website for further details www.thechantry.org.uk

I will provide Information on accommodation options to those who live beyond reasonable commuting distance. 
On each course, attendees would bring their own packed lunch and other refreshments, or go into the town for lunch.  
Tuition Fee 
£27.00 per person for each course.
Payment of Tuition Fee
Cheque payable to me sent to 8, Silver Street, Dursley, Glos. GL11 4ND. Bank Trans can be arranged if required (let me know).
Deadline for viability of both courses 
Saturday 1st February (5 weeks before the courses are due to run).
Both courses to have a minimum of 10 attendees / fee equivalent. Maximum of 30 attendees on each course. If viability for either or both courses is reached, those enrolled will be informed on the deadline date and arrangements will be able to continue. Further enrolments can be made up to 1 week before the courses are due to run. If the minimum number of attendees / fee equivalent is not reached for either course by the deadline, that course will be cancelled and fees received will be returned to those who have sent them in.
Any queries, do get in touch with the tutor nickchidlaw@gmail.com

- - - - - - - - - - - - - - - -
PERMIAN STRATA IN NORTH EAST ENGLAND: continental dune fields, marine reefs and karstic collapse


Permian Slump Olistolith, Trowe Point

Saturday 7th March 10.00 am – 5.00 pm
During the Permian period (299 – 252 million years ago), the crust that became the British Isles was located just north of the equator, under a hot, dry climate. Here, continental environments characterised the period, except in parts of north, where in Mid and Late Permian times episodic marine incursions laid down mostly carbonate sediments with interbedded evaporites. In the north east of England, Permian strata of both continental and marine origin are well represented and exposed, particularly along the attractive coastline. They are impressive, reflecting a variety of environments: continental dune fields, succeeded by both deep and shallow water shelf deposits, including an extensive bryozoan reef belt 20 miles long and up to 100m high. In some of the marine strata, fish, land plants and land reptile remains are preserved. Localised as well as extensive wholesale landsliding of the marine shelf  is evident. In what are now the onshore areas, the evaporites (chiefly halite and anhydrite) were subsequently mostly dissolved, forming impressive collapse features. Bizarre concretionary structures, which may have developed in much more recent geological times, characterize some of the carbonates.      

- - - - - - - - - - - - - -  
METAMORPHISM AND MINERALIZATION IN THE BRISTOL – MENDIP AREA

Pb & Zn Ores with Calcite, Radstock Museum

Sunday 8th March 10.00 am – 5.00 pm
Following the end of the Carboniferous period around 300 million years ago, the area of the earth’s crust that became the British Isles began to stretch and heat as the North Atlantic Rift basin began to form. In the west of England, subsiding rift basins developed where the Cotswolds and Somerset Levels now lie. Between these places, in the Bristol – Mendip area, the crust was under tension at times, causing opening of lines of weakness including faults, joints and fissures. Into these created spaces, and cave systems, descending and ascending chemical –rich fluids accumulated, cooling and crystalizing to form mineral deposits. They include deposits of iron and manganese in Triassic times, and chiefly lead and zinc sulphides in Middle Jurassic times. Associated with the latter, other fluids spread extensively through porous strata in some areas, metamorphosing them to a silica-rich rock. Subsequently, many of these mineral deposits became of significant economic importance to man. This course will familiarise attendees with the history and character of this mineralization, and the impressive variety of mineral types that have been collected in the area in the past.  

Saturday, 14 December 2019

16th December 2019 to 5th January 2020


NEXT WEEKS EVENTS

16th December 2019 to 5th January 2020


THE FOLLOWING IS AN EXTRACT FROM BRISTOL AND WEST COUNTRY GEOLOGY CALENDARS

MORE DETAILS CAN BE FOUND IN THE BRISTOL AND THE WEST COUNTRY CALENDARS AND ON THE WEB SITES OF THE RELEVANT SOCIETY OR ORGANISATION.


MONDAY 16TH


tuesday 17th

SMFS Evening Meeting
When
Tue, 17 December, 19:30 – 21:30
Where
The Friends' Meeting House, 1A, Ordnance Rd, Southampton. SO15 2AZ (map)
Description
“Geological Cartoons; historical & modern” – presentation by our Chairman Phil James.

Members’ Display Table: Geological Funnies!

Details at http://www.sotonminfoss.org.uk/smfsprog.htm

Wednesday 18th


Thursday 19th

Thornbury Geology Group, 7.30pm, The Chantry, Thornbury
When
Thu, 19 December, 19:00 – 21:30
Description
Thornbury Geology Group, 7.30pm at The Chantry, Thornbury, and every 3rd Thursday in the month.  

Friday 20th


Saturday 21st


sunday 22nd


monday 23rd

Geostudies - Annual Dinner
When
Mon, 23 December, 19:30 – 22:00
Where
The Watersmeet Hartpury, Gloucester GL19 3BT, UK (map)
Description
Annual Geological Reunion Dinner at Watersmeet, Hartpury 7.30 for 8.00pm 

tuesday 24th


WEDNESDAY 25TH


THURSDAY 26TH


FRIDAY 27TH


SATURDAY 28th


SUNDAY 29th


MONDAY 30th


TUESDAY 31st

WEDNESDAY 1st


THURSDAY 2nd


FRIDAY 3rd


SATURDAY 4TH


SUNDAY 5TH



Sunday, 8 December 2019

Dorset Building Stone

Dorset Building Stone

A correspondent has brought THIS FASCINATING SITE to my notice. And it has an accompanying BLOG. So far I have just skimmed a few articles but I am impressed by the thoroughness of the coverage. 

I now know that the Parish Church of St. Peter and St. Paul in Blandford was built by the Bastard brothers using Upper Greensand but they placed the bedding vertically rather than in the natural horizontal position and therefore it has weathered badly. Despite their unfortunate name the brothers produced the finest Georgian church outside London and rebuilt the town after a devastating fire in 1731. 

The site is full of such interesting detail and is obviously a labour of love - well worth looking at - again and again!