Saturday, 3 December 2022

1 Day Field Course with Nick Chidlaw

1 Day Field Course with Nick Chidlaw

Nick wanted to run this course in early October; there were enough people who wanted to go on the course but there was difficulty with the date. So he is going to run the course on Sunday the 5th March. Nick has contacted the people who expressed an interest in the October date, but if you want to join, I am sure Nick can find a place for you. All you need to know is in Nicks advertisement which is below.


  A CIRCULAR WALK IN SOUTH GLOUCESTERSHIRE: shallow tropical seas and rivers, ice age valley incision 

Sunday 5th March 2023   10.00 am - 5.00 pm

The generally low-lying landform of much of the county of South Gloucestershire is interrupted near the village of Cromhall by a steep sided, narrow meandering valley lined by rocky crags. The base of the valley was dammed in the 19th century to form a 700m+ long lake, part of the grounds of Tortworth Court (now a hotel). Some 40m deep, the valley is short: indistinguishable from the surrounding countryside only 2 miles to the south of the lake, and likewise so in the open ground on the lake’s north-west side. The stream that feeds and exits the lake is small, and is a ‘misfit’, occupying a valley cut by much more powerful waters during the ice age. Rock exposures, including the natural crags, track cuttings and old quarry workings provide an opportunity to examine the local character of successive stratigraphic units of the Carboniferous Limestone Supergroup. The strata dip 20 – 30 degrees to the south and south east, demonstrating the structural contrast between that found north and south of the ‘Variscan Front’ in the Bristol area, established by the end of the Carboniferous period some 300 Ma. No previous knowledge of geology or the area will be assumed.   


A handout outlining the day’s programme, including location sketch map, geological map and cross section, illustrated geological history and written log of the succession of strata, will be forwarded in advance of the course to those enrolled.

Note that enrollees will need to:

*     Arrange their own transport

*     Bring a packed lunch and any refreshments (e.g. flask of coffee, fruit juice, mineral water etc.)

*     Wear strong footwear with good tread and ankle support, and have waterproof clothing if weather is poor.

*     There will be no requirement to wear hard hats on this course. 

Attendees will be insured against accident for the duration of the course. 

Tuition fee: £30.00 

Contact tutor Dr Nick Chidlaw to enrol and for any queries. 

Deadline for course viability: Friday 6th January. If the course has become viable (minimum of 10 enrolments) by this date, enrolments will be able to continue until 1 week (Sunday 26th February) before the course runs..   

Google Earth oblique image of the study area, looking south showing the abruptly-incised meandering valley and lake near the village of Cromhall. 

Track cutting in the Cromhall Sandstone Formation (Middle part). The character of the Carboniferous Limestone Supergroup changes notably between South Gloucestershire and the Mendips; in this area in the north, reddish quartz sandstones and mudrocks, deposited in rivers, occupy much of its upper part and are virtually absent in the south. 

Saturday, 26 November 2022

Anyone Want an Indoor Geology Course?

Anyone Want an Indoor Geology Course?

The following has appeared on the Teme Valley Geological Society's mailing list. Some of you may be tempted to reply to John Nicklin at



We have previously raised the question of geology courses. Nick Chidlaw has offered a wealth of these, both in and outdoors.  For now perhaps focus on the indoor ones (although the formations are much more visible in the winter months of course). 

 Here is one--£30/person min 10 enrollees:--

PERMIAN STRATA IN NORTH EAST ENGLAND: continental dune fields, marine reefs and karstic collapse 
Indoor day 10.00 am – 5.00 pm  Martley Hall

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. 
Nick also runs a course on our local Martley geology but he felt that you would all know this too well (hands up, I don't, so maybe he assumes too much)

I know email circulations are not usually productive in assembling groups of participants, but let me know if you will. When? If numbers materialise we'll sort it out as Nick is pretty busy.


What If the Asteroid had Missed?

What If the Asteroid had Missed? 

The asteroid hit at the end of the Cretaceous, killed off the dinosaurs (birds are the only survivors) and gave mammals the space to thrive. THIS ARTICLE by a Bath academic speculates on what would have happened if the asteroid strike had not happened.

Was the arrival of intelligent tool-users inevitable? And would they be dinosaur descendants. 

Probably not. Sauropod dinosaurs had a long history of being huge in body, small in brain. From the Jurassic to the end of the Cretaceous this held true.

Carnivorous dinosaurs had a similar history - big bodies, small brains.

This recipe may not have been a precursor of intelligent tool-users but it would have been enough to stop mammals (especially us) from becoming such.

Brain size versus body mass for dinosaurs, mammals, and birds. Nick Longrich

The development of mammals was not inevitable. Monkeys in South America remained as monkeys. Primates in South America never (even after at least three starts) develop large brains - they went extinct. 

Only in Africa did we emerge.

This is inevitably a very speculative article, but well worth reading.

Thursday, 24 November 2022

GeoNews Autumn/Winter 2022 Edition

GeoNews Autumn/Winter 2022 Edition 

The latest edition of GeoNews - the Geo Conservation Newsletter - has been published. You can get it HERE or read it below.

Down to Earth Extra December 2022

Down to Earth Extra December 2022

The December edition of Down to Earth Extra has been published. You can dowload it from HERE or you can read it below.

Friday, 18 November 2022

Why are There 8 Billion of Us?

Why are There 8 Billion of Us? 

You can find one set of answers to this intriguing question HERE. And among the answers is friendliness! Compared to Neanderthals, Homo sapiens (thats us) lived in larger groups and interactions with other groups were more likely. Thus finding a mate from outside your family was more possible. Genetic deformities are less common in Homo sapiens than in Neanderthals.

(As an aside, I have been told that the invention of the bycycle was the cause of vastly improved genetic health in the nineteenth century.)

Homo sapiens may have had a slightly higher rate of reproduction; their friendliness encouraged the creation of networks which allowed the spread of technologies which got us through changes in the worlds climate. Other humanoid species were less resilient.

This is an interesting article, even if much speculation is involved. And it has the following graph which is frightening!

Based on estimates by the History Database of the Global Environment and the UN. Max Roser, CC BY-SA

Saturday, 5 November 2022

Dragonflies in the Carboniferous

Dragonflies in the Carboniferous 

A correspondent has sent me the Newsletter of the British Dragonflies Society which contains an interesting aricle about Griffinflies. You can sign up for their Newsletter near the bottom of THIS PAGE.

To save you going through the rather long newsletter I have reformatted the Griffinfly section and you can get it HERE. Or read it below.

For me the greatest interest was the discussion on the gigantism of the beast and it relationship to the higher oxygen levels of the Carboniferous. Gigantism may have more to do with the lack of predators than with oxygen levels. - Very interesting!