Wednesday, 31 December 2014

March 2015 - Two one-day courses - Scotland and Cotswolds

Nick Chidlaw is offering two 1–day courses next March, using a format that has pleasingly attracted many students on previous occasions; these are indoor-based, and describe field areas to which Nick has run courses in the past. One of them describes a particularly striking example of volcanic geology in east central Scotland, the other focuses on the diverse strata deposited during the Ice Age in part of the west of England, many of which are only occasionally exposed. The courses may be attractive particularly to people who are not in a position to visit field locations, e.g. insufficient time available because of family/work commitments, health problems, or may be interested in the opportunity to study lithologies from exposures that are no longer extant. 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.
The venue is the Buckingham Room (single storey building by the car park) at The Chantry, 52 Castle Street, Thornbury, South Glos. BS35 1HB.  Tel: (01454) 414268. See venue website for further details, including location map.
On each course attendees would bring their own packed lunch and other refreshments, or go into the town for lunch.
These two 1–day courses have a fee of £25.00 each.
If you / anybody else you know would like to attend either or both of these offered courses, please contact Nick Chidlaw.
Please note: these courses are to run on the same weekend, but are independent of each other; you can enrol on both if you wish to, or one of them, according to your interests / availability.
The deadline for the minimum number (10) of enrolments is Saturday 7th February (4 weeks before the courses are due to run). Maximum number of attendees on each course 30. If the minimum number for each course is reached by this deadline, the arrangements will be able to continue, if not, the course(s) not reaching viability will be cancelled, and fees received will be returned to those who sent them in, soon after. Enrolments above the minimum numbers for each course will be able to continue for up to 1 week before it is due to run.

Saturday 7th March. 10.00 am – 5.00 pm

From latest Devonian times, through the Carboniferous period and into Early Permian times, the crust of what is now northern Britain was firstly stretched, later compressed and finally stretched again by plate tectonic forces. These forces caused movement on major geological fault systems, releasing pressure in the crust and allowing magmas to rise from inside the earth, both into the adjacent crust and onto the surface above. In Scotland, from c. 350 million years ago during the early Carboniferous, this igneous activity continued episodically for the next 100 million years producing, besides intrusive rocks such as the enormous Midland Valley Sill-complex, over 6600 cubic kms of lavas. Most of the magma generated was of ‘mafic’ (magnesium and iron rich) composition, crystallizing as dolerites and basalts, and associated pyroclastics. During this time, the crust that became the British Isles was located in equatorial latitudes, and central Scotland was occupied mostly by swamp, lake and river systems in which abundant plant debris produced carbon-rich sediments. The interaction of the magmatic activity with these sediments and environments produced some striking results, including the formation of curious carbonate rocks called ‘white trap’, and catastrophic explosions of ‘Surtseyan’-type when magma erupted up into water.  Across the eastern part of the county of Fife, an impressive number of discrete volcanic centres (over 100 recognised) occur, many along the coast where their interior ‘architecture’ can be examined in excellent exposures. This indoor day describes cryptovents and collapsed tuff-rings from the Fife and East Lothian coasts, sub-volcanic plugs at the Lomond Hills and North Berwick, basalt and spilite lavas at Kinghorn, and the volcanic complex at Arthur’s Seat, overlooking central Edinburgh.             
A handout outlining the day’s programme, and a list of optional suggested reading, will be provided on the course. No prior knowledge of geology or the study area is assumed. 

Sunday 8th March. 10.00 am – 5.00 pm

The Quaternary corresponds to the geological period we are currently living in; it includes what is popularly known as ‘The Ice Age’, together with the much milder climatic episode that began when the last glaciers in the British Isles disappeared, and which continues to the present day. The Quaternary period is currently accepted internationally to have begun about 2.6 million years ago, and is divided into two major parts: the Pleistocene epoch (corresponding to ‘The Ice Age’), and the post-glacial Holocene epoch, divided at about 8,000 years ago.  Detailed studies show that The Ice Age was in fact composed of cold or glacial conditions alternating with interglacial climates as warm, or warmer, than today, each of these alternations lasting tens of thousands of years. In Britain as elsewhere, this climatic ‘restlessness’ has had dramatic consequences: as ice sheets have grown and retreated, they have changed sea levels, caused extensive erosion of the earth’s crust, movement and deposition of the resulting sediments, caused the crust itself to sink and rise, river systems to drastically change their courses as well as downcutting or infilling their valleys, and forced animal and plant life to migrate, leading in some cases to extinction.
Erosion in the British Isles has been very extensive during the Quaternary, so that deposits older than about 600,000 years are very fragmentary. In the uplands such as in Scotland and Wales, repeated glacial action has successively modified landforms and removed older Quaternary sediments, resulting in a limited legacy from which to deduce events. In the lower lands of eastern and southern England, where glaciers reached their maximum extents, the landforms and sediments are better preserved, and the oldest and most diverse record can be found. The Severn Vale and Cotswolds, lying within this tract, has a great variety of Quaternary landforms and deposits, developed over a wide time range. On this course you will be introduced to these landforms, including anomalous river drainage patterns, dry valleys, river terraces, estuarine platforms and landslides; and deposits laid down by rivers, glaciers, freeze-thaw action, springs, and the Severn Estuary. These deposits are mostly not normally exposed, but some become temporarily so by man e.g. for sand and gravel extraction, and ground engineering projects; the tutor has examined a number of these, and their details will be described. Course highlights include the Cotswold scarp being one of the most extensive areas of landslides in the British Isles, and evidence for the Severn Vale not existing prior to the beginning of the Quaternary.
A handout outlining the day’s programme, and a list of optional suggested reading, would be provided on the course. No prior knowledge of geology or the study area is assumed.

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