Belfry Bulletin Number 173

B

No 173 July 1962

Monthly Journal Of The Bristol Exploration Club

B Vol. XVI No. 7

The annual season for form filling is now upon us! In this issue of the B.B., you will find the entry form for the 1962 photographic competition. Next month will come the usual nomination form for the 1963 committee and in September's B.B. will be the voting form.

All of which goes to show that the A.G.M. and dinner is not as far away as you might think. Most people reckoned that last year’s dinner was a good one. We all hope to make this year's an even better one. It's at the Cliff Hotel, Cheddar on Saturday, October 6th.

Although it is hoped that the general standard of the entries for tie photographic competition will be even higher than last years, don't be kept from entering because you think that your slide or print is not good enough. It may be that your entry has that something which catches the eye of the judges; but even if it hasn't, you may like to have the chance to have it compared with the best the club can do. Have a bash!

The song competition does not appeal to as large a section of the club as the photographic competition.

This year, we are going, to rehearse it beforehand and also arrange it so that you don’t have to be afflicted with it if you don't want to. For those who like this sort of thing, we hope that somewhere - in some sordid garret maybe - the winning song is even now being written.

Finally, DON'T FORGET THE CLOSING DATES!!! _______________________________________________________________________________________

CAVING LOG 1st April. St. Cuthbert's. Mikes Palmer & Wheadon, and Albert to Cerberus Series & thence to Pyrolusite.

1st April. St. Cuthbert's. J. Eatough, M.Baker, R. Bennett, K. Franklyn, C.A. Marriott. Collected the Eatough maypole from Upper Traverse Chamber and took it into Cerberus. Both high level passages in Mud Ball Chamber maypoled. One on right proved to lead to Lake Chamber. Signs of a previous visit. Rift continues on far side of Lake Chamber and will be maypoled at a later date. Exploration continued in Coral Series. Passages above the rift near Annexe Chamber were pushed without success. Attention was switched to Coral Chamber and a new pitch discovered by Mike. This was not descended as no ladder had been taken.

A further hole was looked at but found to connect back to Coral Chamber. It is proposed to call the rift “Fracture Rift” and the leaders will be informed of this proposal.

Coombe Down Freestone Quarries. 2nd April (1 am). M.R.O. Rescue. M. Baker, M. Palmer, P. Buck, M. Wheadon, H. Kenney, J. Hanwall. A two hour search for missing schoolboys. An interesting trip (if possible at 1 am) in a maze of mine workings that are in a rather dangerous condition. First time the B.E.C. has gone caving with a bitch (police dog). We never did see the boys!

7th April. Goatchurch. Ray Chris, Phil and John from the Midland association of Mountaineers, Pat Irwin, Gordon Tilley and Jon "Rotten" Ransom. Full trip + drainpipe.

7th April. Swildons. Four from M.A.M. as above and Pat. The M.A.M. party cherishing the hope that they could keep their feet dry. This was shattered at an early stage by one member getting his wet by water that entered down his neck. The 40 was found to be laddered and the whole patty descended. The first man down was misguided enough to swing under the waterfall. The 20 was then encountered and passed and a considerable length of passages traversed before a return was decided upon. A very damp but contented party emerged from the hole only to find that it was raining. Loud complaints.

Heale Slocker 8th April. M. Baker & Alfie. Digging continued at Alfie Speed (what does this mean?)

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July 1962

LUMINESCENCE

by M. Luckwill.

In the last article (1) we looked at the mechanism of photo-luminescence. Two other forms of luminescence might with convenience be noted here. They are Thermoluminescence - light emission caused by heat and Triboluminescence - light emission caused by crushing, rubbing or scratching.

Table 1 shows the occurrence of luminescence noted by several authors (2,3,4) and + indicates that some forms of the mineral luminesce. In the Mendip area, we are mostly concerned with Calcite, Limestone, Arragonite and their various forms.

We remember that luminescence is caused by an impurity. Very little of this impurity is necessary however, and if too much is present, the energy is dissipated as heat rather than, light. The amount of impurity we are concerned with will defy spectrographic analysis and requires neutron diffraction techniques for tracing and identification. I believe that stal from Balch's Hole has been analysed spectrographically and found to be free from trace elements within these limits of accuracy.

Difficulties occur, therefore, when we wish to discover the nature of the impurity. Most research has been stimulated by the recent advances in semiconductors and consequently, although quite a lot is known about transition elements in host crystals - such as germanium - little work has been done using limestone as a host crystal. However, of interest to us, is a method of dating limestone by thermoluminescence.

The method is not reliable because of a variety of variable factors, but briefly, the theory is as follows:Activation centres are caused by cosmic radiation. The number of activation centres is related to the amount of radiation received, which in turn is related to the age of the limestone. When limestone is heated, luminescence occurs and the light intensity is related to the number of luminescent centres (5). Hence the age of the limestone can be found.

It has been found that magnesium and strontium act as activators and that iron acts as an inhibitor.

From Mike Baker's article we might draw the conclusion that CaCO3 which has been dissolved and re-deposited luminesces more than the original carbonate deposit. This could be due to trace elements being held in solution due to their small concentration, thus deducing their concentration in the stal and enabling luminescence to occur.

These trace elements play an important part in the crystal formation, and a knowledge of their identity will give further insight into the formation of cave deposits. This knowledge might well be gained by further analysis of luminescent materials.

Table I. Mineral & Composition Calcite Limestone Magnesite Smithsonite Siderite Strontiamite Arragonite Dolomite Barytes Celestine Anglesite Gypsum Fluorite Sphalerite Lepidolite Pectolite Amblygonit Feldspar Apatite Scapolite

CaCO3 CaCO3 MgCO3 ZnCO3 FeCO3 SrCO3 CACO3 CA(Mg)(CO3)2 BaSO4 SrSO4 BaSO4 CaSO42H2O

Flour Phospho- Thermo- Tribo References. +

+

+

+

+ + + + + + +

+ + +

+ +

+ + +

+ + + + +

1. Luminescence. B.B. 1962, 172. + 2. DANA's Manual of Mineralogy - 17th + Edition.

3. Wade & Mattox. "Elements of Crystallography and Mineralogy."

4. Harper. "Geoscienoe" Series.

5. Edward J. Zeller “Thermoluminescence of + Carbonate Sediments� Nuclear Geology.

6. M.J. Baker. Afterglow. B.B. 1962, 171.

+ + + + + +

Number 173

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PHOTOGRAPHIC COMPETITION. There will be SIX classes this year. Prizes will be awarded to the winner and runner-up in every class EXCEPT class 6.

CLASS 1 CLASS 2 CLASS 3 CLASS 4 CLASS 5 CLASS 6

CAVING CLIMBING CAVING/CLIMBING CAVING CLIMBING Best Special

2" x 2" Colour Slide 2" x 2" Colour Slide "Two and a quarter square" Colour slides.

Black & White print.

Black & White print.

Slide or print.

RULES 1. All entries must have been taken by the competitor.

2. All competitors must be PAID UP members of the B.E.C. 3. No professional photographers may take part.

4. No entry must have been previously entered in any competition.

5. No more than TWO entries may be submitted in any one class.

6. No competitor may win more than one FIRST prize.

7. A picture entered in one class may not be entered as a print or slide in another.

8. Monochrome prints must be POSTCARD size or larger.

9. The judges may not compete.

10. No responsibility for loss or damage is to be borne by the organiser or by the B.E.C. 11. In any interpretation of these rules, the decision of the organiser is final.

12. THE CLOSING DATE FOR THE PHOTOGRAPHIC COMPETITION IS ON FRIDAY,21ST SEPTEMBER, 1962 AFTER WHICH DATE NO LATE ENTRIES WILL BE ALLOWED TO TAKE PART. Readers will find an entry form with this B.B. In any case of doubt, please get in touch with the organiser M.J. Baker, "Morello", Ash Lane, Wells, Somerset.

Competitors who will not be at the dinner should make some suitable arrangement with the organiser for having their entries returned. If postage is necessary, please include cost of return. _______________________________________________________________________________________ Apologies for the shortness of this B.B. - the first one of only two thirds the number pages this year - and also for its lateness. The editor has been afflicted with "finger trouble" (literally) by getting his hand mixed up with an empty beer glass - that'll teach him to muck around with EMPTY beer glasses in future. _______________________________________________________________________________________ DON'T FORGET THE DATE OP THE A.G.M. & DINNER - 6TH OCTOBER

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July 1962

KENT’S CAVERN

by Jon Ransom.

On my way through Torquay, I saw a large sign reading 'KENT'S CAVERN'. Following various arrows I arrived at a small car park with an imposing modern building facing it. I paid my 2/- and went into the waiting room, all excited to think that I was going underground with about thirty other weegees.

While waiting, I compared the general layout with the fronts of Gough's and Cox's. Kent's seemed to be cleaner and more informative about the caves. At this stage the guide arrived, took our little tickets (or tallies) swung open a massive oak door, and led us into the unknown.

The cave is located on the side of a hill, which it penetrates for about half a mile. The rock consists of the Devonian limestone and sandstone which, with the mineral deposits from the soil above, give some very striking and colourful effects in the cave.

Just inside the entrance and down to the left are the remains of a hyena den, and the abode of prehistoric man. The remains of mammals of that era have been found in great number and include mammoth teeth and remains of fox, badger, hyena etc. There are also several remains of bear, including an excellent skull and leg bone which may be seen embedded in a false floor, which the guide then takes you underneath.

The main tourist section has been excavated in some places to a depth of twenty feet and you can see, as you walk through, the line of the original floor level high above your head.

Several of the formations are very good, and there are also quite a few straws and helictites which can be seen in odd corners on the tour. These do not occur very frequently however. Most of the passages and chambers show good signs of the water which formed them and mud in the numerous side passages is fairly thick and sticky. These passages shoot off in all directions and, when asked about them, the guide said that a lot of them were unexplored. He went on to relate how school kids often went up these passages, to reappear with hundreds of bones. I think that the guides of Kent's are in strong competition with those of Gough's and Cox's and that all guides go to a special course in tall caving stories.

Apart from housing prehistoric man (and woman!) many inscriptions found on the walls of the cave go back as far as the fifteenth century. One of these inscriptions is a woman's but many are difficult to decipher as they are covered with a thin layer of calcite.

Although Kent's Cavern is a show cave, and has an imposing entrance and the guide builds up the place as much as he can, it is worth a visit from any caver who finds himself in the district even if you only go in to hear the guide’s tall stories! _______________________________________________________________________________________ The Belfry Bulletin. Secretary. R.J. Bagshaw, 699, Wells Rd, Knowle, Bristol Editor, S.J. Collins, 33, Richmond Terrace, Clifton, Bristol 8.

Postal Dept. C.A. Marriott, 7'8, Muller Rd, Eastville, Bristol.