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28 June 2021

Summer Programme 2021: NEWS

 

The Committee met last Friday evening, and after a detailed discussion we concluded that in view of all the current uncertainties we could not yet feel confident about arranging full-scale field trips, at least for the next two months.

To fill this gap, we have arranged two more ‘virtual field trips’ using Zoom, and Peter Reynolds and Andy Moffat have very kindly agreed to lead these. Both will be at 7.30 pm, and the details are:

 

Wednesday 14 July – Peter Reynolds: 'Underground in Assynt'

Most members of our Society are familiar with Assynt. It is a classic area for the study of geology. They will also probably be aware that it contains caves. The Bone Caves in particular are familiar to most visitors. However, there is far more to underground Assynt than the Bone Caves. Beneath the limestone there are many kilometres of passages large and small as well as vast chambers and even archaeological remains.

If ever there was a sport that is connected to geology it is caving, and Peter has been caving in Assynt for many years. He will give us a guided tour of some of the major cave systems as well as describing the history of cave exploration in the area.

 

Wednesday 11 August – Andy Moffat: The missing millions, the 'dead continent' and the boring billion:  The Lewisian-Torridonian unconformity at Clachtoll, NW Sutherland.

Andy will discuss the superbly exposed and accessible Lewisian-Torridonian coastal unconformity at Clachtoll where there are also other geological features including shear zones and hydraulic fractured gneiss.  

We will 'visit' each of the three beaches where, as the beach size decreases, in turn the geological complexity increases.  There are also nearby inland unconformity exposures. 

The Lewisian formed 3.0 billion years ago from metamorphosed granitic-like rocks.  Where exposed at Clachtoll, it shows repeated metamorphic events with the last recorded (Inverian Event) in the eroded and exposed rocks 2.45 billion years ago. 

The basal conglomeritic Torridonian Stoer Group was deposited on the eroded Lewisian 1.2 billion years ago.  

This geological gap across the unconformity represents 1.25 billion years of missing Earth history.  What does this mean and what other geological processes during this time are represented elsewhere on the planet?

We will also look at unconformities in general.  Some of which are obvious, others much less so.

The basal Torridonian conglomerate may also be confused with brecciated shear zones.  In addition, beach boulders of hydraulic fractured gneiss superficially resemble a breccio-conglomerate.  We will look at the clues to distinguish easily between these rocks.

Images of rock exposures will also be presented of outcrops not normally visible except at very low tides or when beach sand has been stripped away by storms.

Alan Thompson will send out the usual Zoom joining details shortly before each talk.

 

In addition, it is hoped to arrange some small-scale recces, the outcome of which would be either a virtual field trip, or a plan to visit again with a bigger group, or both. Ideas (not promises!) under discussion are:

- Ullapool Thrust – Alan Thompson and Anne Cockroft

- Portmahomack  – Dave Longstaff

- Elgin fossils (museum and in field) – Dave Longstaff and Alison Wright

- Meall a Ghiubhais  - Stephen Young

We plan to visit these locations over the next month or so and review what is possible.  These will be in very small groups and arranged at short notice.  If you would like to join in, please contact me or the relevant leader- see below for email addresses. 

If you have other ideas or suggestions, we are keen to hear them.

 

Finally, we are hoping to run a field trip to Portsoy in September. Further details will follow in due course.

 

Alan:                  alanrossthompson@hotmail.com 

Anne:                 hgssec@gmail.com

Dave:                 daveandkaren21@btinternet.com

Stephen:            sstyoung84@gmail.com

 

Winter Programme 2021/22

Matters may be clearer by September, but at present we do not know what we will be allowed to do, or what all our members will be confident about doing, in the way of live meetings.

We are therefore putting together a winter programme which can be run using Zoom (one at least certainly will be) but keeping the option of changing to live meetings if that is realistic.  We know that some members prefer the Zoom meetings and we will consider how they can be included if/when we go back to live meetings.  The programme is almost complete and the details will follow when it has been confirmed.

 

Shetland 2022

We are determined to visit Shetland in 2022.  The plan is very much as previously discussed, and provisional dates are:  1 June evening leave Aberdeen on ferry, 10 June morning arrive Aberdeen.  The numbers are limited, and the 14 members who signed up for 2020 get first refusal but, if you are interested, please contact Anne Cockroft.

 

Best wishes,

 

Stephen

Chairman, HGS

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