Rock Sniffer's Scribbles

A few more Tanzanian Piscines

2012-01-26T05:58:00.002Z

I took a couple of days field break in the nearby town of Mtwara, sans internet, and managed to get a dive in at the "Monoliths" site and the "Fish Market" site near the town.

Dive equipment, camera and buddy were from Graeme Marrs at ECO2 dive centre in the former slave port of Mikidani, a couple of km along the coast from Mtwara.

The two dive sites differ markedly. The Monoliths are pinnacles rising to about 10m below sea level from a harbour bottom at [considerably greater depth - you're not going there without a squeaky voice], and giving a good reef-ish or wall-ish dive requiring a boat.
(As always, the photos below are considerably reduced from the originals.)
The usual suspects were visible. Moorish Idols were strutting their stuff all over the place, then showing off their thinness the moment you press the shutter :

Moorish Idol on the Monoliths

They can be a bit of a tease, because they're reasonably unconcerned by photographers coming up on them, but they dart around a lot, often disappearing because they're so thin laterally.

Meyers Butterflyfish

This one is considerably less common than the Moorish Idol, and moves away more rapidly. It's also very laterally compressed, showing the almost disc-shaped form of the typical Butterflyfish. Very pretty.

The Tanzanian relaxed attitude to ... well, everything ... is obvious in some of the fishes too (this one on the Monoliths) :

Siesta time

The Monoliths was a fun dive, but having quite a bit of swash (we'd got 1-2m of swell on surface), we were getting bounced around quite a bit, which makes photography a bit awkward. Then we moved on to the Fish Market, in the harbour area of the town. This is a "muck dive" - a muddy bottom giving way to the south to patch reefs. Lots of life in the mud, but also lots of debris from the (literal) Fish Market onshore. This site can be done as a shore dive too, without requiring excessive (and most un-Tanzanian) levels of masochism, unlike the Monoliths, which would be severely hard work, even given good navigation.
A lot of the life hides down in burrows or under logs.

Shrimp ( Rhynhocinetes durbanensis ? approximately) on the underside of a log ; catfish under the log itself.

The common anemone fish are present on the more reefy bits, including this couple who are not interested in having any photos taken of their homes.

See you! Nemo!

They really are territorial, and that makes them easy to photograph. So people do.

Platyhelminth - a.k.a. flatworm. colourful, so probably horribly poisonous.

Towards the south end of the Fish Market site coral heads become more common, with more vertebrate life.

Peekaboo !

Or maybe it was looking for a place for a nice kip? It was very definitely siesta time by then.

Sites : 10 Degrees South (and ECO2 dive centre ; adjacent)

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Monoliths (approximate ; don't try navigating off this) :

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And finally, the Fish Market :

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This is also called the Dhow Port, for fairly obvious reasons. The rotting remains of a tug boat are beached here, and the dive runs SSE from there.
All in all, a fun day in the water, and tyhanks and a plug again for Graham and ECO2 for organising the trip. And a Bajaji (Piagagia 3-wheel taxi ; a "tuk-tuk" in most of the rest of the world) back into town after a fine meal and +1m decompression stop.

Onshore Tanzania this time

2011-12-25T06:03:00.002Z

I've just got back to the rig - same Caroil rust bucket as before - but this time on an onshore job near the village of Ntorya, in Mtwara province, southern Tanzania.

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I don't anticipate anything like such a festival of photography on this job, largely because I'm 20-odd kilometres from the coast, in the middle of a lot of scrubby rolling hillocks. There's also the minor point that I didn't bother bringing a camera with me this time, just what is in the phone.
I might end up with some good "bug photos" though. There's a LOT more insect life around the site than at Nyuni - which indicates how impoverished the fauna on the island really was.

Call off the search parties - Nemo has been found!

2011-08-28T17:57:00.010+01:00

Had another swim back out to the reef this lunch time, along with Howard the DD. I went out a few days ago too, and deliberately didn't take the camera to make sure it was a shorter trip. Needless to say, on that trip I saw lots of interesting things, but with no evidence, they're already fading in my memory.
But today's snorkel ...
Howard was having plenty of fun.

Which is the purpose of the exercise.

Turtle shell
After much splashing around, and hunting for the reef break (where there is a line of coral heads at 4-5m, with a lot of life), we headed back towards shore.
I spotted this turtle carapace, laying on the seabed.

Last time I was here on Nyuni, I found parts of a turtle plastron (the front, dorsal or belly piece of the shell. And I'd found washed-up pieces of them on the beach too. So finding a carapace wasn't a great surprise.
After I'd taken a couple of photos of it as it lay on the seabed, interior with the ribs visible upwards, I was wondering if I'd have any hope of getting it back home. CITES, paperwork, difficult. And look at the size of it - that drag anchor for the goodie-bag is about 12cm long. I'm not getting that into my rig bag!
So, I got my photos first, then looked at the problem of "Can I carry this to shore without drowning?", as a necessary precursor to "Can I get this through customs?"
Then I turned it over. Surprise time!
The shell started to delaminate. This dark outer covering came off as thin flexible sheets of a plastic-like material, with a layer of flesh (fatty?) bonding it onto the expanded ribs of the carapace (the bony shell).

I decided that I wasn't going to be able to carry this back to shore. The rest of the "get through customs" problem becomes a non-problem.

It's still there, if you want it. Though it's probably moved with each tide.

Next thing I spotted ... Can you see him? (Or, more likely, her?)

I saw it snaking across the seabed, then hiding behind this rock.

This is a crop from the main image above.

It's a Moray Eel, I think a White-eye Moray, but I'm not certain on that.

And for about the 4th time, Blogger's accursed post editor has lost 4 or 5 photos that I uploaded. And this is a really horrible, horrible editor.

A different type of puffer fish.

Oh, sorry, Blogger has lost the original picture of a different species of puffer fish.

And finally the bloody anenomefish that inspired the title of this post. Unfortunately the pictures have got so screwed up and I don't have time to struggle with this pathetic editor any more.

Where Am I?

2011-08-10T08:44:00.003+01:00

People have been asking.
The link above should (should) centre on the rig location.
Oh, hang on, what does this do?

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Lots of code ; what does it do? Oh, cool. Saves me lots of screen-shotting etc. It's got the usual controls too.
Camp is here :

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Bar is here :

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It all adds up to a small island off the coast of Tanzania called Nyuni.

People who know me will know that I'm obviously here looking for enchyaline Blue Holes out on the reef, with the intention of discovering "Caverns Measureless to Man" containing Pleistocene alien craft. So far I've found a choked sinkhole that obviously takes water when it's raining, which averages every 2nd-3rd day. "Toto, we're not in Britain any more!"

See earlier posts for swimming photos. Fishy things which haven't tried to eat me (yet).

The aerial photography is obviously a couple of years old. The island has acquired a squatter camp of several hundred people since I was here last, a resident rat problem (goes with the rubbish in the squatter village), and the maintenance as a coconut plantation seems to have been abandoned, so scrubby undergrowth is slowly taking over from the palms. Which by comparison with SongoSongo Island to the south (with it's airstrip), seems to be the normal vegetation for the area.
Oh well, back to the grind of searching for CMTM!

More Ice Island News

2011-08-09T19:19:00.002+01:00

Petermann's Ice Island - location update.
For those that haven't been keeping an ear to the, err, water, this is a rather substantial lump of ice that fell off Greenland a year ago. It's slowly working it's way out towards the Atlantic Ocean, where it has the potential to become a significant hazard to shipping. And to the oil installations on the Grand Banks.
The link above gives more detail, including notes I've been making on it's progress over the last few months.
I've just made time to update my satellite surveying (details in Patrick's blog, above), and when last visible (Aug 05th), the berg was just off the northernmost tip of Newfoundland, near Belle Isle. Latitude 51.53N, Longitude 54.95W.

Before long, if not already, it should be visible from the coast of Newfoundland.
And if it does decide to wander off through the oil fields ... there will be "interesting times".

Nyuni - Batch #4 - boat round the island.

2011-07-27T17:43:00.004+01:00

Various of us took one of the boats for a trip round the island. Nothing particularly spectacular to be seen form the boat, but once we were back into the lagoon, I went over the side to a patch reef that the boat-master indicated.
First thing to draw my attention was a patch of "Needle Sea Urchins" amongst corals (a species probably in Acropora, but I won't hang for that). Just pretty.

While photographing that, I noticed that, for reasons still unclear, the sea urchins were congregating in particular patches. I don't know why ; I guess that there was something about the substrate that they liked there, but not elsewhere.

A brilliant blue+yellow fish was shoaling in the area.

They particularly liked gathering around a large lobster pot on the reef, but they would also follow each other around over the reef edge too (where I wasn't going to go on ALP, Available Lung Power).

After much hunting around on the net, I identified these as Yellowtail Fusiliers ; they shoaled with Twinstripe Fusiliers, which are only marginally less colourful. (Though this picture doesn't do the colour of the two yellow stripes justice ; I'm going to have to start using the colour balance tool for these duck dives to 3 or 5m.

On my next dive, I spotted this "different" branching coral - which I can't identify.

I've spent more time than I care to think about staring at this sort of assemblage of fossils and sediments ("wackestone to packstone", anyone?), but even so it was very nice to see these environments "in the flesh" as it were.

Nyuni - batch #3

2011-07-27T13:27:00.009+01:00

Attempted to swim out from east end of the island to the eastern barrier/ fringing reef. Didn't get there. Partly through meeting this "cleaner station" (?) on the reef top. Organisms : "brain coral" (fewer zombie jokes, please) ; sea urchins (one of 3 genera seen on this swim ; others have more robust spines in two different colours (which may or may not be important) ; the yellow-black striped fish is, I think, a "Sergeant Major" (distinguished from the Convict Surgeonfish by relatively thicker black bars, and the body being yellow above and silver-white below) ; and the blobby B+W fish looks like it should be a Clown Fish (stars of "Nemo: Found", or some film like that) ... and indeed, visually it looks like a "Saddleback clownfish". But that's a Western Indian Ocean species (not a problem itself ; coelacanths went one way, why couldn't something go the other way?, AND it should have a yellow mouth. Looking on the web ... there seem to be several closely similar species. And considerable intra-specific variation. So I'm not going to worry too much more about it.

Next! Well , after leaving the "cleaning station, I carried on out toward the reef front. But things were getting gradually more interesting as the water very slowly got deeper. After 50mins of travel, I got to this area where - hard to see in static photos - there were in the order of 30 more "LBJ" shoaling around in the seaweed. Obviously, the brownness works for camouflage.
Then ... horror of horrors ... the battery went flat!
Well there's a lesson : if swimming OUT to somewhere, try to do it on your back to avoid being distracted.

And that's me caught up to today!

Nyuni, Tz, Batch #02 : Today, I swims with zee fishes

2011-07-25T15:41:00.005+01:00

Title to be spoken in a menacing gangster-esque voice. "Sung Soprano", or something like that.

Went for a bit of a swim yesterday, but there is quite a current around high tide on the headland of the island, so I moved round to the south. Between wind and current there was quite a chop going - 30cm or more, which made snorkelling a less than comfortable occupation.
Fair amount of sea life, but I made no attempt at getting out to the reef margin - I'm really regretting not bringing my fins to Nyuni, but may have a Cunning Plan (TM, Pat.Pending).

Snorkelling in very shallow water, I was being constantly buffeted by the swell. So when I tried videoing things, the steadiness wasn't. No point in even thinking about shrinking them to something postable.
Firstly, these lobate or fan-shaped organisms (a major component of the biota :

I've named the file as if they're seaweed, but the more I think about it, the less I'm convinced. The colour isn't wrong for some algae (red photosynthetic organisms are nothing new), but the paleness of the colour ... doesn't make sense. They're thick enough to be more-or-less opaque, so why not absorb all the light you can in your waveband? Besides, I'm pretty sure that I've seen something similar common in UK waters, but can't find it in online compendia of algae ... therefore, it's probably not an alga. Could they be Bryozoa? But my memory tells me that Bryozoa have stiff meshes as a water filtering device. Rather like a stalk-less crinoid. Which doesn't really fit for these. [SHRUGs ; moves on]

I can't find these yellow-bar-fish in any online references either, but that's probably just the crudity of my search techniques. These wriggly things that go under the name of "alive fossils" don't really attract my attention until they've got fossilized. But this couple of "yellow-bar-fish" seemed to be defending the seabed hole against big ugly me. So once I'd taken a few photos, I moved on. (Without fins, holding station in chest-deep water against around a 1m/s current was a noisy affair.) There's a flashy fish in shot as well - brilliant reflections of "structural colour". I don't recognise either species.

THIS is what happens to people who look (too closely) at the small stuff. (American Scientist, v99#4 p311)

"Wow. A tube worm actually emerging from it's tube! Isn't this the most exciting thing you've ever seen?"

--
Aidan Karley

Fun with Fysiks

2011-07-24T08:58:00.002+01:00

A review of this book ("How the Hippies Saved Physics : Science, Counterculture, and the Quantum Revival" by David Kaiser, 2011) in this bi-month's American Scientist by David Woit starts with a personal (Woit's) anecdote about the problems of getting a physics job in the mid-1980s :

[a sizeable group of physicists] appeared to have managed to pursue scientific research by dropping out of academia and adopting a countercultural lifestyle that included soaking in hot tubs at Big Sur, engaging in Tantric sex, hanging out at North Beach cafes and taking psychedelic drugs. Some of them had gotten rich writing books that mixed physics with various kinds of mysticism. I wasn't very interested in the mysticism part, but I figured that I could handle the rest.

[Edit : link to article]
Needless to say, I was reading this while towelling myself off after a nice 3/4 hour swim in the Indian Ocean, collecting a nice specimen that got me thinking all sorts of interesting palaeontological thoughts on the topic of ecdysis, enjoying a cup of coffee, and thinking about ambling back up to the drilling rig to engage in my paid work for the day.

I think I can handle the tribulations of this job too!

--
Aidan Karley

Batch #01 from Tanzania

2011-07-24T05:55:00.002+01:00

I've arrived on the sunny island of Nyuni, but am stuck behind various firewalls, so have to post indirectly to get my pictures to the outside world.

To quote my earlier email :

"Bloody Internet here is as wobbly as whatever. And lots of stuff is blocked too.

Attached is a batch of photos ... Needless to say, these are drastically-shrunken versions of the original photos, as the "-small" suffix in the file names might give away.

First image :
2011-07-21 11-28 Tanzania, flight over Rufiji delta, This is Kiechuru inlet, rivermouth bars forming with breakers DSCF1496-small

2nd ..2011-07-21 11-39 Tanzania, Songo songo Island DSCF1507-small.

3rd ..2011-07-21 11-43 Tanzania, Songo songo Island, baobab tree beside runway DSCF1510-small.

4th ..2011-07-21 12-29 Tanzania, Boat journey to Nyuni DSCF1523-small.

5th ..2011-07-21 12-55 Tanzania, boat journey to Nyuni DSCF1554-small.

6th ..2011-07-21 13-16 Tanzania, Nyuni reef DSCF1565-small.

7th ..2011-07-21 14-48 Tanzania, Nyuni home sweet home DSCF1566-small.

8th ..2011-07-23 13-04 Tanzania, Nyuni, white bird DSCF1570-small.

9th ..2011-07-23 13-05 Tanzania, Nyuni, boats on south shore DSCF1571-small.

I've made a horrible mess of crossing the links and the photo names, but I'll know better in future posts. I'm sure one can figure out what it's meant to do, but it is now lunch time and my belly is growling.

Plans for a bit of a party.

2011-07-04T08:33:00.002+01:00

Stef is back in town, briefly ; arranging a meeting with Jools and Jane. Need to scan those suspicious photos.
--
Aidan Karley

[Delete as appropriate]
Geologist (BSc, FGS)
Disreputable megalomaniac genius (by the standards of the average yucca)

Mars Rover Driver gets into SF story

2011-06-18T00:02:00.002+01:00

Who : Scott Maxwell and the fairly small Brotherhood of Mars Rover Drivers

What : They've been name- (or job-) checked in a recent SF short story.

Where : Karl Schroeder, of Canada, in the story "Laika's Ghost" ; published in at least the "Engineering Infinity" anthology, but possibly elsewhere.

When : Published 2010, but some of the stories are copyrighted 2011 ; go figure. ISBN 978 1 907519 51 2

Why : Well, the anthology as a whole is pretty good (so far ; not finished reading it yet). But I started using this "twatter" thing recently and I heard of the Mars rover driver who "twits". So I started "following" him (sounds like I became his stalker!) and then he (or his character) turns up in a book I'd ordered for completely other reasons.

If the world is small, then Mars must be even closer.

Differential Survival Across the K-T Boundary: A New Theory on Why the Dinosaurs Perished but Reptiles, Birds, Mammals and Amphibians Did Not

2011-05-04T15:37:00.000+01:00

Differential Survival Across the K-T Boundary: A New Theory on Why the Dinosaurs Perished but Reptiles, Birds, Mammals and Amphibians Did Not

He's an amateur studier. Seems serious.

He's come up with what he thinks is a novel idea to explain why the dinosaurs "got it" while birds and mammals didn't.
I actually printed this off to have a peruse on a flight a few months back, and I've got some scribbled notes somewhere ... somewhere safely tidied away. Have to try to find it again.

Facebook photo album

2010-06-26T14:55:00.001+01:00

Bit of archaeology. Bit of geology. Bit of wildlife.

http://www.facebook.com/album.php?aid=2042873&id=1501300611&l=50d7e9f58d

Damned good holiday.

--
Aidan Karley

Geological Heraldry

2007-01-28T09:29:00.000Z

Who : Oksana and I
What : Went to the Burns Night Supper
Where : Beach Ballroom, Aberdeen
When : Last night (27th Jan 2007)
Why : Wedding anniversary, and Burns night itself is a good enough excuse.

Nice night out. Oksana hadn't met "Scottish Country Dancing" before, which was fun. It is, of course, obligatory that 2/3 of any dance floor have absolutely no idea what they're doing, no sense of rythym, and don't care either.
Sketched up some geological heraldry on the traditional napkin while thinking about what to get engraved onto my kilt's belt buckle. Unfortunately, the scan isn't up to much, and I've no illusions about my drawing skills. The armorial description I came up with was "crossed hammer and chisel/ crowbar, quartered with compass, hand-lens, scoop and specimen bag. Motto in scroll surmounted is `In Lithos Veritas` ".
No, I can't remember much of the rules for describing heraldry. Well, it was 30-something years ago that I had to learn it in history. One of the more interesting things I learned from that teacher, whose name I've forgotten.

Getting to work

2006-08-14T09:43:00.000+01:00

I made a few notes on another site a couple of days back:

Hmmm, interesting times today.
Just been handling the consequences of yesterday's terror scare. Looks like we're either going to have to spend several hundreds of dollars each-way for staff to travel to the take-off point, and probably a similar amount for hotel accommodation at the near end because of the backlogs of people leaving here. Or maybe it'll be quicker and safer for the Cheshire Crew to travel direct to the take-off point instead of travelling to the congregation point first.
No flights today between England and Scotland. That means there won't be any train seats either, and the A68 and M74 are going to be gridlocked. Not going to be fun for people to travel with.
The Daughter has just been invited to Edinburgh next weekend. But since that's the same train routes, they're likely to be full too. Difficult.

I've been doing a bit more thinking, while trying to get arrangements made for visiting Prague in the next school holidays. Apparently Heathrow is reporting 20 to 30 % of flights being cancelled, because the airport can't handle the search requirements. Well, I don't expect the silly restrictions to be relaxed ("soon" or "anytime" is up to you ; I don't specify a time becasue I don't think they'dd be relaxed. Ever.), so that's going to be a long-term drop in the search capacity of the iarports. Add to that the prevention of any electronics in the passenger cabin and I foresee a big drop in business travel (would I trust my laptop to baggage handlers? No.). A big, permanent drop.
That's going to make the whole economic base of the aviation industry get very ill. Very, very ill.

Updated - midday 14th August. They're allowing laptop bags back on board, at least for BA, from tomorrow. Someone else has seen the same problems looming.

Boring coring.

2005-12-01T11:40:00.000Z

George wants to see some core coming out of the ground. Well, no names, no pack-drill, but here's a few pix from a recent coring job. (When I've finished unpacking them and cutting off the identifying marks.)
Coring is a pretty uncommon activity these days - the only time it's really necessary is to get undamaged samples of a reservoir for porosity/ permeability measurement, and even then the results are somewhat suspect because the core is typically flushed through with liquid filtrate from the drilling mud, and that can damage the porosity of the rock sample.
An interesting job I was on a few years ago was where the client wanted to compare the vertical and horizontal permeability of the reservoir. Here, even if there were porosity damage, it shouldn't differentially affect the vertical versus horizontal properties. Has that file finished extracting yet? Nope.

Half an hour later ... well actually the photos I took on that coring job were much more boring than I'd remembered. Only one worth bothering with really, and none of the actual coring operation (unless you want photos documenting that the core barrels had sub-standard orientation markings - didn't think so).
The photo is of the cut end of a section of core, which I photographed in the driving rain of a wet and mosquito-ridden evening. The blade used to cut the core has cut more-or less straight and planar, so the wiggling of the fine beds of dark material indicates that there is irregular bedding here. In the NE of the image you can see that one of the beds is thinning quite substantially over a small distance. (You can also see most of a centimeter scale bar). The saw nick in the NW of the image is where we broke off a chip for microscopic examination.
Then we wire-clipped a cap onto the end of the fibre-glass barrel, nailed it onto a box with it's neighbours, and packed it onto the back of a truck to go to the core analysis lab, never to be seen again (at least, not by me).

Day in the (death) of a worm

2005-11-28T11:53:00.000Z

Click for full-size image?
Just been digging around in the rock pile, and I found this rock which I'd recently described in a USENET post:

The cohesiveness of consolidated mud would 
provide a comparatively resistant surface over 
which coarser-grained sediments could be 
transported as a package. 
Actually, thinking about it, I've a nice specimen 
in my rock pile showing a similar event from 
100-odd million years ago. Mid-jurassic of the 
Isle of Wight, there was a muddy sea-bottom 
with a rich fauna of burrowing worms chomping 
away buried in their nice muddy burrows. Then 
along came a flood of silty sand which buried 
and killed off the worms leaving a series of 
sandy casts of the top ends of the burrows on 
the *under* surface of a circa-2cm thick sand 
bed.
One hundred million years later along comes a 
superannuated hippie of a geology student who 
extracts said thin sand bed from a 10-odd metre 
high cliff of similarly interbedded muds and 
sands, and carefully appreciates the day in 
the death of these worms before spending 
hours in the pub (and back in the honours 
year student labs) carefully picking out the 
bits of clay from between the casts of the 
burrows.

"AA" size cell and a ruler to give scale objects. The autofocus of the camera seems to be slipping, and there's no manual alternative. I'm thinking that I can almost justify getting a new camera.

2005-11-29
Carsten described these as "escape structures". I don't think so - I think they're burrows which the worms (lugworm or equivalent) died in after getting a belly full of sand. The underlying mudstone bed contains sub-vertically oriented sand tubes dispersed through the mud, representing the worms which swallowed a sand meal, stopped eating, swallowed (separating the swallowed sand from the continuous sheet), then died.
Please note that this photograph is of the UNDERSIDE of the slab as originally found, in a normally oriented sediment sequence.

Programs for George

2005-11-20T21:53:00.000Z

Who : George from sci.geo.geology
What : BBC programs
Where : Here
When : now
Why : so George can listen to the programs.
Hah, well that was a waste of time and effort.
Sorry George.

Silverpit structure

2005-03-22T12:38:00.000Z

There has been a bit of discussion lately on the interpretation of the "Silverpit" structure in the Southern North Sea.
A couple of years ago a paper was published in Nature about a circular set of faults surrounding a sub-surface depression in the top-Cretaceous reflector. The interpretation was that this was an impact structure. A summary of the paper can be found at the Geological Society website (if you're really interested, I can email you the paper). Well, there have been alternative interpretations published over the last few months, re-interpreting it as a sagging structure caused by withdrawl of Zechstein salt at depth. John Underhill (of Edinburgh University) has presented data orthogonal to the original section (link above), which does put a very different interpretation on the structure.
It still doesn't look right though - the "central peak" structure in the original paper is still a very anomalous structure, and Underhill's interpretation of thickness variations in the overburden to the salt is inconsistent - the Cretaceous thins in one direction and the Jurassic in another, combining to give the appearence of synsedimentary halokinesis. It still looks odd to me.
I am very surprised at a seismologist of Phil Allen's experience not looking out-of-plane though.