Shameless stuff...

 The rocks of Rouken Glen

Here's a wee hip-hop thing about the Carboniferous geology of Rouken Glen Park. I did it for Scottish Geology Festival in 2022. My pal Dale helped with the finding the music backing track, and the recording.

It was posted on Twitter in the days when Twitter was mostly OK, and it was available there until the current management took over in 2023. I left then, and later shut down the account. 

At last,  it's back online!  :)

 

 

 

 

More thoughts on good and bad rocks

In my experience, most geologists have a powerful aesthetic sense about rocks. Some rocks spark joy, while others leave them bereft.

 

I've written about this before, but here are some further thoughts.

So what is is that makes a rock good? I think that a good rock is one which which has good characteristics. 

So, if we think of a rock as "igneous", it should be very igneous indeed. We don't want any damp,  low-temperature shenanigans obscuring the fiery conditions of its formation: we want to be able to get as much high-temperature information out of the rock as possible. If we are look at a mantle xenolith, it should be as mantley as possible, not equilibrated with some tedious basalt, or the damp Earth surface. Freshness is key.

Similarly, a nice sedimentary rock should preserve as such of its early formation, precursor materials, (and biota) in as pristine a state as possible. You need some diagenesis to make a nice strong, rigid rock, but too much diagenesis is definitely bad **. Sedimentary structures are always good. Cements, overgrowths, and diagenetic phases should be clearly distinguished. Mudrocks are better if they preserve exquisite lamination. An oolitic limestone should have ooids preserving the most delicate banding within the ooids. Ideally carbonate rocks should have a carbonate cement which is visually and chemically distinct from the grains.

And if you're going to metamorphose a rock, do it right. Don't just make a nice sediment into some anonymous finely foliated crud. Grow proper new crystals. Make them visible. Give them colour: red garnets, blue kyanites or sapphirines, pink corundums, green omphacites or pargasites. Probably give them some fabric: a touch of foliation or folding is always nice. In general, high grade rocks are better than low grade rocks, but it's not quite as simple as that. Nice big new crystals are good at any grade, while sanidinite-facies porcellanites are usually pretty dull. Time and fluids are key here: long cooking times with a fluid phase produce nice rocks, whereas shorter  cooking may lead to rocks which are underdone. A fine-grained eclogite is simply a missed opportunity. If you're going way down deep, don't just get there, and immediately get the next bus home. Stay for a while to enjoy the conditions, grow some nice crystals, and come back as a beautiful red-and-green wonder-rock.

 

And even if you like weird stuff, like fluid flow, or retrogression, or the formation of fault gouge, the same principles apply. There will be veins, alterations and fault gouges that sing of the processes that made them. And there will be others that don't.

 

Finally, in order for a rock's story to have proper meaning, it needs context.  It needs to relate to other rock stories, and to the stories of people and events. A good rock needs a sense of place. Good, precise locality data and geological context data make all rocks better. Even terrible rocks can become not bad. And even the best rocks will be even more delightful.

 

Quality matters - seek out good rocks. You will understand more, and have more fun doing so.

 

[Picture of a good rock]

 

[Picture of a bad rock]

 

** unless you're talking about septarian concretions, which are *ALWAYS GOOD*.

Special golf clubs for playing on lava flows?

Recently, I got a research enquiry, seeking a nice fresh olivine tholeiite (a kind of basalt). The specimen had to be big enough to allow a decent-sized offcut to be taken for destructive experimental use.

After a brief search through the Hunterian museum rock collections, I found an ideal rock (R21646).  It had been collected in the 1920s by MA Peacock and GW Tyrrell, from the post-glacial  Hvaleyrarhraun lava flow, on the Reykjanes peninsula in SW Iceland. Here's what it looks like under a polarizing microscope:

Hvaleyrarhraun olivine tholeiite lava between crossed polars. FOV about 2mm wide. Very little actual olivine in this view: mostly greyish plagioclase crystals, and brighter coloured clinopyroxene, plus dark holes in the slide (bottom left and right).

I've worked with igneous rocks from all over the world for quite a long time, but to my shame, I've never really got to grips with Icelandic lava terms, or places, so I took to the web to find out more about this locality.

This link appeared near the top of the Google results, indicating that the lava flow (dating from ca. 950 AD) now hosts a golf course.

I don't own this T-shirt, but it's a pretty good summary of my views on golf. However golf on a lava flow sounds better than normal golf. And, even better, it seems as though special clubs may be required:

the front nine holes feature no grassed roughs, only closely mown turf, semi-rough and lava. No bunkers can be found on these holes, only on the older back nine where they are very much an integral part of a links concept. Unlike many other lava golf courses, e.g. in Hawaii and Tenerife, golfers at Keilir are able to play recovery shots from the lava areas. Indeed, many golfers carry a special „lava wedge“. This is quite unique, since on most lava courses, lava is treated as a lateral hazard.

 A "lava wedge"?   This sounds excellent. However, Google has so far failed to reveal any pictures of such a gold club. Their use is hinted at for courses on Hawaii and Bali, but I can't find any pictures, or videos of such a thing in use.

Any contributions welcome...

PS The Icelandic "..hraun" suffix seems to be used to name particular lava flows when used in placenames. The "Hvaleyrarhraun" means something like "Whale sandbank lava".  This flow is also described as "helluhraun" to indicate smooth-topped, ropy lava. Usually today, geologists use the Hawaiian word "pahoehoe" for this type of flow - I hadn't heard of this Icelandic alternative.

Rock against.... the Poll Tax

This item has being lying around in my office for around 20 years.

My new curatorial colleague, Nicky Reeves, spotted it the other day, and was intrigued. It's a cheque, carved on a broken slab of "Emerald Pearl" larvikite, a Permian alkaline igenous rock from near Oslo, in Norway. Here is its story.

As older readers will know, the Poll  Tax, (officially known as the "Community Charge") was introduced by Margaret Thatcher's Tory government in Scotland in 1989-90, where it proved record-breakingly unpopular. The following year, it was introduced in England and Wales, where it soon became equally unpopular.

At this time, I was working in the excellent Leicester University Geology Department, and living in and enjoying the fine and mysteriously-underrated city of Leicester. Leicester had a Labour council, who hated the tax, but were forced to rely on it for income.

This left me in a dilemma. Paying the tax would be taken as support for it. Or at least acquiescence to it. Not paying the tax would deprive the council of money needed for schools, rubbish disposal, roads, museums, etc. What was I to do?

I had discovered that cheques did not need to be written using the official bits of paper from a cheque book. It was "well known" that a cheque had been written on a cow by a disgruntled farmer, and found to be legally valid. (I believed this at the time, but see here ). So I decided to write cheques on tablets of stone. This would be enjoyable, appropriate for a geologist, and would ensure that my money was accompanied by a clear and forceful statement of protest. Also, when it comes to messages, you can't get better than tablets of stone.

 I inscribed the stone (using a pneumatic air pen like these) , and then took it to the bank, where it was slid under the security glass at the counter (In one later case, where a larger slab was used, the teller had to come came out to collect it). Staff at the Midland Bank (now closed; this building on London Road in Leicester) took the process entirely in their stride, and the money was taken out of my account, and transferred to the council at record-breaking speed. I subsequently paid several more Poll Tax bills in the same way.

My protest clearly helped* By the time I returned to Scotland in 1992, having got a job at Glasgow University, the Poll Tax was obviously doomed, and it finally expired in 1993/4.

A few years later, I was revisiting Leicester, and wondered what had become of my stone cheques. So I went into the Midland Bank branch on London Road, and enquired. All cheques have to be retained for some statutory period. Rather amazingly, two of my stone slabs were still "on file", I think in the same branch. All I had to do to get my slabs back was to write a couple of paper back-dated replacements to go on file in their place, and I was able to walk out of the bank with the stone cheques. One (on slate) is now in the numismatic collections of the Hunterian Museum, while I have kept this one.


* It would be interesting to know if anybody other than the bank staff in the London Road branch of the Midland Bank ever got to know of the existence of my stone cheque protest. Realistically, probably not. but I like to imagine that they did play some small, and perhaps decisive part in the demise of the Poll Tax.

University of Glasgow Spain field trip 2014 - team photo!

Here are the Glasgow final year Earth Science students and staff, on a beautiful sunny day in the sandstone hills north of El Chorro in Spain.

Another great day on a fantastic field trip. The rocks under and behind us represent the filling of almost the last channel connecting the Atlantic and Mediterranean, between 7.3 and 6.2 million years ago. Once the Mediterannean became isolated, it dried up completely for around 400000 years, before being refilled through the Straits of Gibraltar.

Spanish chameleon and dog

I am currently on the Level 4 Earth Science field trip to southern Spain, with 35 students and colleagues Tim Dempster, Trevor Hoey, Martin Lee and Cristina Persano. Weather is scorching, and rocks are great (more on this elsewhere), but first, some animals.

First, a squashed and mummified chameleon, seen two days ago in  Carboneras Fault zone

in SE Spain:

Today we were working around Sorbas, and at the Cuevas de Sorbas car park, during our assessement and summary lecture-ette sessions, we we joined by a very nervous Spanish dog. She eventually got up the courage to come close enough for a pat, and was eventually rewarded with a ham sandwich from Viviane.

Scottish gold!

Last week, I drove a Land Rover up to Tyndrum to collect a large sculptural block of rock for the Hunterian's forthcoming Scottish Gold exhibtion. Chris Sangster, the Scotgold CEO kindly accompanied us, and we were able to drive right up to the Cononish mine along the access track.

Although the mine is currently being developed, the mine dumps are mostly the result of development work carried out by Ennex in the 1980s, and it's amazing how quickly the rock surfaces are becoming colonized by mosses and lichens. However, we managed to find a nice large block of rock cut by abundant quartz veins:

Having the vehicle beside the dump makes collecting such large blocks easy!

Afterwards, Chris the designer, and Neil the photographer spent a long time standing in the river with a fancy camera on a tripod, capturing the essence of the gold-rich landscape.

Blockbuster exhibition opens on 14th March!