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Post by dazbt on May 23, 2009 17:32:13 GMT -5
I've seen this subject disscussed recently in some detail on another (more academic) message board, group forum, as I am sure other members of this CCM forum have as well. I wondered what thoughts and experience others might have on this subject, I have a reason for asking that I will put forward later.
Slickensiding is basically accepted as being the resultant polished surface created at the point of an interface of seperated strata where at least one surface has moved against the other. (I think)
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Post by John on May 23, 2009 18:07:10 GMT -5
Was enthralled by the academics too! ;D
From the NCB's booklet on "Coal"
" The rocks close to the break or fault plane are generally crushed and broken, and the surfaces are often highly polished because one side has slipped under enormous pressure over the other. Such polished surfaces are called "slickensides"".
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Post by tygwyn on Aug 12, 2012 18:05:10 GMT -5
Plenty of evidence of this occurence in the South Wales coalfield,Jumps we used to call them,minor faults really,caused by pressure from the main faults.
Apparently,a big problem in the Margam Mine,and them still wanting to use 300m longwalls,i ask you.
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Post by dazbt on Aug 13, 2012 1:14:20 GMT -5
Here's a snippet linking both this slickensiding topic and Spanker's mention of Eyam Edge (Derbyshire) mining;
A Lead Ore Explosion in Hay Cliff Mine, Derbyshire, 1738
This excerpt from White's History, Gazetteer and Directory of the County of Derby, 1857
"Hay Cliff Mine, in Eyam Edge, now no longer worked, was once the grand depository of that extraordinary phenomenon, in the mineral world, provincially called Slickensides. The external appearance of this curious species of galena is well known wherever mineralogy has been studied, At the present time, good specimens of it are extremely rare, and can only be met with in cabinets that have been long established. In those mines where it has most prevailed, it exhibits but little variety, either in form or character. An upright pillar of limestone-rock, intermixed with calcareous spar, contains the exploding ore; the surface is thinly coated over with lead, which resembles a covering of plumbago, and it is extremely smooth, bright, and even. The effects of this extraordinary mineral are not less singular than terrific. A blow with a hammer, a stroke or a scratch with a miner's pick, are sufficient to rend the rocks asunder with which it is united. The stroke is immediately succeeded by a crackling noise, accompanied with a sound not unlike the hum of a swarm of bees; shortly afterwards an explosion follows, so loud and appalling, that even the miners, though a hardy and daring race of men, turn pale and tremble at the shock. In the year 1738, an explosion took place in the Haycliff mine, when two hundred and fifty barrels of material wore blown out at one blast, each barrel containing 350 pounds weight. During the explosion, the earth had a tremulous motion, as if shook by an earthquake."
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