Dear All,
Whilst certainly not comprehensive, this is an interesting Link if only for
the photograph... which is somewhat interesting in that the lithology is a
conglomerate.
Farey's description in his vol. (kindly supplied by Chris), is indeed
v.interesting in that it suggests that the stresses involved are not confined
to the slikenside itself but to ground some way beyond. It is also of note
that he states that he was not able to find out whether the Eyam mining area
slikensides were still behaving as they were, suggesting that either no
more had been found (unlikely), or, that the area might have become
de-stressed due to mining activity - a possible scenario, but maybe the phenomenon
might be confined to a certain region of depth... with these mines having by
this time passed below this region. Possibly certain lithologies might be
more prone to holding and retaining fault stress more than others? - softer
lithologies such as shale would absorb/readily disperse rather than hold
tension, whereas a hard lithology would retain it and become brittle.
I ponder on one point. I wonder how widely the stresses involved in these
particular areas/occurances, will be dispersed once they have been
sufficiently relieved by mining activity in a certain area? Is it possible that once
such 'activity' as has been referred to ceases (as described by Farey
etc.), that the whole slikenside is deactivated and relieved of tension? One
wonders at the connection between other slikensides and their association
with each other... and the association with faults (mineralised or not), in
other words might there be a 'swarm' of them in this particular area very
localised area of Derbs.? - and within a certain depth range (and might they
have been created by the faults?). The lack of reported occurrences of this
phenomenon after the dates referred to does seem to suggest that 'something
has happened'.
Regards, Bernard
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_http://en.wikipedia.org/wiki/Slickensides_
(http://en.wikipedia.org/wiki/Slickensides)
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