Fake dinosaur footprint.

Very quick post.

Geology class
A faked dinosaur footprint. A4 clipboard for scale.
On a field trip to Arran.
In 1985
We don't know who carved this fake dinosaur footprint, but the carver didn't notice that he (she?) cut across several sediment beds (NNE to SSW lineation in this view), marking it as an evident fake.
Photo has suffered from fungus and bad storage for years before being scanned. The carving is pretty unrealistic too.
Prompted by the footprints recently reported from Skye.


"BrexitExit" and the costs of Hubris

In the aftermath of the disastrous (for the Tory Government) 2017 general election (for clarity - the one in June ; I remember 1974 and the two general elections that year, and I'm not going to rule out a second one this year), the question of how badly the UK Government's team at the upcoming "Brexit" negotiation will be weakened is obviously of importance. On one side will be a team from the UK's DUP-CUP Coalition of Chaos, constantly looking over their shoulders to see if they're getting the sack this afternoon, and on the other side a team of professional negotiators with homes to go to and careers that won't be badly affected one way or the other by the result. It's not going to go the way that the Government  or their Brexit supporters want. And the deal that will be aimed at by the professional EU negotiators will be one that is so bad for Britain that it becomes an unavoidable question whether or not it is worth carrying on.
 The UK Government is going to have to try to exit from Brexit. Hence the tag "#BrexitExit".
At that point, one would expect - "require", even, since part of the charge of the EU government is to extend and enhance the EU - the EU negotiators to extract some political payment. If membership of a club is considered an attractive thing, then defectors must be punished, and punished publicly. 
I think one of the high probabilities of a demand for suspending Article 50 and ceasing Britain's efforts to leave the EU will be Britain signing up for the Euro.

The fact that this would be utterly repugnant to many of the political engineers of the whole Brexit debacle would, of course, be one of the motives for making this demand. There are swords which have not been fallen upon, and that is not an acceptable end point of the process. 

I'm also trying to remember an aphorism to the effect that "Those who the Gods wish to destroy [for their sin of hubris], they will first drive insane." [See footnote]
Boy, was PM Theresa May suffering a severe attack of hubris when she called the election, and now it's either Furies or Harpies that are keeping her awake at night.

Links : (submitted as comment/ idea to a journalist on NZZ, Neue Z├╝rich Zeitung) Back-link?

Footnote 1 : "DUP-CUP" Democratic Unionist Party is well known ; the official name of the Tories has always (well my political lifetime, at least) been the "Conservative and Unionist Party" ; normally Tories refer to themelves as "Conservatives", but when first toadying to the DUP, May started using the full name, and telegraphing what was coming by that wording.

Footnote 2 :  That phrasing actually seems to be from the 1870s by Longfellow, but the concept has been traced back via multiple re-uses to Sophocles' Antigone lines 622-624

that a man can reason the bad
into good, when a god
seduces his wit.


What to do about global climate change?

Lots of BLAH but several things are clear :
- Climates are complex. Certainly more complex than we DO understand;  possibly more complex than we CAN understand (without using machines) ;
- People are in deep - ostrich mode (obvious from coverage) ;
- by combination, the two above mean that nothing will be done, until too late. (It may already be too late.)
Hence, the increasing interest in "geoengineering". But which of the many possible schemes to follow? Surely a more difficult, and important, question.

The first point is important. Many proposed schemes interfere with complex systems in complex ways. It is perfectly hard to predict the consequences. Another concern is the time LAG between action and effect and (not unreasonable ) concerns of overshooting the desired end point. Another reasonable concern is the plausible disproportionate effect of controls on people less responsible for the problem.
SO . . .  I see the simplest solution as
(1) change insolation, not the atmosphere. The atmosphere is just too complex.
(2) change the insolation in space
(3) add components  (and so effect) in small but simply additive increments.

My proposition: combine magnetic force propulsion with solar sail technology and the properties of the L1 Lagrange point.
- Orbital objects near L1 stay there with little station-keeping effort.
- This is an area around 1Gm (a million km) from Earth, on the Sun-Earth line.
- The Sun (and Earth) has a non-trivial magnetic field in the region of L1
- At L1 the area covered by the Sun is AROUND 1000km across. Area
- We have TRIED  (failed, not for relevant reasons) to launch a solar sail of around 100m diameter.
- To reduce insolation by 1%, of blocking solar sail would be needed. That is a lot of launches, but not immense. Incremental improvements will increase effectiveness of each vessel and launch.

Update : Does the Earth's magnetic field extend out to a million km (L1)?



S.F. Portegies Zwart and E.P.J. van den Heuvel

Was the nineteenth century giant eruption of Eta Carinae a merger event in a triple system?


 2015 paper referring to the 1838 to 1860-ish Eta Carinae outburst#

 They propose that before 1838 (in Earth's reference frame) Eta Carinae was a triple massive star system. The 1843 outburst was the result of a merger in 1838 (which formed the ~90 MSol main star of the present system), followed by the 1843 impact of the third (non-merging) body of the initial trio with the expanded envelope of the merged star.

Interesting idea. Stimulates the obvious question of what is the prognosis?

Ohhh, I hope they passed it through a native-English speaker (or translator) before publishing things like "Also if our model would finally not be the one that explains all the chanacteristics of Eta Car, still and evolution as discribed and modelled here is expected to happen not rarely in nature."

So, what is the lookout for the future of Eta Car? Apart from "uncertain"?


New Year 2015-2016.

New Years pretty sky things.
 London skyline from Primrose Hill. A huge pall of smoke from the fireworks drifts east  from the Eye (site of the firework display) ; the Post Office Tower shines somewhat excessively in the foreground. And the Moon and Jupiter look down on the whole lot, unconcerned.
The park's ground has been trashed. And rubbished severely too. Both Oksana and I got hit by flying (falling) champagne corks in the last minutes of the nominal old year.
 More traditional firework photos.

New Year's Eve weird things. The sheep in the back row has 3 horns.
Seriously. I suspect a developmental problem. But this being the Land of the Inbred Yokels (Cotswolds), it could be someone's idea of a joke.

Close up :

Quite how someone could attach a third horn to a sheep is one question ("Why" is another), while I could envision developmental issues where a horn could be duplicated. Then there's always the "parasitic twin" explanation.


Decoding a hallmark

A hallmark is a set of marks made on a piece of precious metal to indicate it's quality, as verified by a particular assay office.
The hallmark normally contains - an indication of the controlling assay office (a national body, or a local one for a city or region) - the type and quality of the metal - the manufacturer - and frequently an indication of the date of manufacture. Naturally this information is of great interest to the  dealer in antiques and jewellery. Naturally therefore they are also prone to being forged. For a long time then, the stamps used to make these marks were very fine pieces of the metalworker's art, to discourage copying by unauthorised people. Again, this makes them a target for forgery.

I have been examining a ring which I brought from a jewllers as Oksana's engagement ring. I got the size drastically wrong - it was the first ring I ever brought - and it has long needed to be rebuilt to fit her much smaller fingers. And in the process, I've been examining the hallmarks.
Well, I can get something out of that :
- the 4th character is a 5-petaled Yorkshire rose - which is the symbol for the Sheffield assay office.
- the boxed "375" is the gold count in parts per thousand. 375/1000  is 3 parts in 8, or 9-carat.

The rest of the symbols - I need to take a closer photo (and the ring is currently at the jewellers), or get the sketchbook and loupe out.


Basket Katz

"Basket Katz" (Mikki) is a friend's cat. In Bavaria.
 The reason for his nickname is fairly obvious.


A human side to a giant

A Neil Armstrong Anecdote

I like my science fiction, so some years ago I made a strategic decision : one of the proven routes for a novice SF author to get known, and to get experience in writing, is to write short stories and get them published in a magazine. So I took out a subscription to Fantasy and Science Fiction - not necessarily the highest in the pantheon, but they were in danger of going under, so I thought - that's a decent punt.
I'm getting what I expected : some great stories, some poor ones, some tedious editorial (I do not need to read about yet another bloody werewolf-vampire romance!) and some great editorial. Though to be honest, I'm less than diligent about reading them when they arrive - I tend to chuck them into corner of the bookshelf and take them to the rig for bedtime reading.
So, I rip open an un-opened envelope on the plane to Gabon here ... and it's the Nov/Dec 2012 edition. Been laying on the bookshelf since just after we moved. Oops.
And there's a great little anecdote in the editorial about the (then recently deceased) first man on the Moon, Neil Armstrong.
Now, there's a lot of hagiography about the man. First Man on the Moon ; the Right Stuff ; fluffed his lines on the biggest outside broadcast in the history of humanity. But there's not a lot about the man himself - after he retired from NASA, he didn't do a lot of public stuff, retiring into the background. His second-in-command, Buzz Aldrin, has been more famous in recent decades, if only for punching out the lights of a Moon Landing Conspiracy whackjob. Way to go, Buzz! and give him one in the nuts from me!
But back to the Neil Armstrong anecdote. The editorial, as befits the last number for the year, looks back at major events of that year, including, unsurprisingly Neil Armstrong's death. Gordon van Gelder, the F&SF editor, then recounts the following anecdote of a more human Neil Armstrong, ascribing it to one Lucius Shepard, though it doesn't appear on Sheperd's website.
I kinda met Neil Armstrong once back in the late '70s. My brother-in-law and I ran a T-shirt company and we had a couple of lines we sold to museum shops and at science fiction cons and like that. We were coming back from a sales trip, driving through rural Ohio, when we spotted a sign advertising the Neil Armstrong Museum in some little town. What the hell, we said. Maybe we can dump some shirts, so when we got to the museum we sat down with the curator, who was also the buyer for the gift shop, and pitched the shirts. We had a kids' shirt that resembled the body of a NASA space suit and the guy bought about 7, 8 dozen of those, along with shirts that had maps of the moon and Mars, the big red spot on Jupiter, etc. I don't recall how the subject came up, but I asked the curator if Neil ever came around the museum and the curator said, "Oh, sure. He's here all the time. I think he's here now." I asked if we could meet him and he said that Neil wasn't big on meeting new people and besides, he was probably sleeping. "He likes to sleep in the lander," he said. "He spends a lot of time in there."
"The moon lander?" I asked.
"It's a replica," the curator said. "It's up in the Moon Room, on the second floor. You can go on up if you'd like. Maybe you'll see him."
We went up to the second floor. There was a walkway that ran across the building, a bridge of sorts, then a gap that separated us from the Moon Room, which was a display of a life-sized lander sitting on some pumice-like material, and in the distance some painted crater walls, lunar mountains, and a black sky with stars. It probably looked fairly real when the lights were off, but the lights were on full and it looked pretty fake.
We hung out for around five minutes and then gave up on the idea of seeing Neil.
We went back downstairs, finished some paperwork and had a cup of coffee with the curator. I said I thought it struck me as weird, Neil Armstrong sleeping in the moon lander. The curator said maybe so, he'd never given it much thought.
Before we left we ran back up to the Moon Room to try and catch sight of Neil...and there he was. He was standing on the ladder leading up to the hatch. A guy with buzz-cut hair was all I could make out. We waved at him and after a second or two he waved back. I had a feeling he'd been on the verge of leaving the lander, but after that one wave he ascended the ladder and closed the hatch behind him.
That's all there is. Not much of an encounter. I used to think I'd write a story about seeing him, but it never came to anything. I liked thinking about Armstrong sleeping in the lander, though, the kind of dreams he had there and all. It made him seem a lot more real than that BS one small step for mankind quote that someone wrote for him. And it makes his death go down smoother to imagine him curled up in that cramped space on his padded couch, on his way to somewhere no one else has ever been.
 Well, yeah. That's nice. Different to the run of the mill. I'm really going to have to make more of an effort to read things when they are new.
(There are some good stories in that number of F&SF. You can get a copy, or a subscription, from their orders page.)


Skye, June, 2010

A couple of years ago I had a great  break on Skye, doing some archaeology, some walking, a bit of wildlife photographing, and just generally having a good time.
I posted a photo album about it on FaceJerkOff at the time, but since I've been getting increasingly distrustful of their policies since ... well, since they existed, to be honest, I've been taking my content off there in fits and starts, and I guess now is the time to move that album off too.

Uamh an Ard Achadh - "Cave of the High Pastures", or "Tin Can Alley" in times gone by (the current farmers are much more appreciative of it than previous ones, who just considered it a trap for their beasts). A natural limestone cave which appears to have been used as some sort of ritual site in the Mesolothic to early Iron Age, with modification of the cave entrance by dry-stone dyking, probably ploughing (ritual? - earliest agriculture in the area?) and the deliberate (or at least, non-accidental) burial of valuable artefacts.
It's a bit hard to see (this is not a site report!) but the meandering path of the deeply incised entrance runs away towards the dig which is in material piled up behind dry-stone dyking at the downstream end of the entrance passage.

The area is just plain beautiful.

 That's a nice view to wake up to in the morning.
 The fluffy highland coo. About as natural to the area as humans are, and probably imported from central Europe with the "Neolithic Revolution" around 5000 years ago. but they've settled in well.
 On Saturday and Sunday, the professional archaeologists have days of rest, so I did the same and took a boat trip around the islands of the Inner Minch - the so-called "Small Isles". A sea-stack with very evident columnar jointing - basaltic volcanism.
 Sea fidos. Gurt wet slobbering blobs.
 Puffins - they hardly look as if they can take off, and it's a huge performance.
 Basking shark. Big shark, no teeth.
 From the "behind the wall" deposits. It needs conserving properly, but it's an iron spear head. In it's day, this was your Porsche, crossed with an Exocet missile. Or something broadly equivalent. We may not know what was the process of thought was that led to it being positively buried behind a stone wall in a modified ritual site (which had probably been in use for a couple of THOUSAND years by this point), but we do know that it was not an accidental loss.
 Archaeologists often complain about being presented with finds "out of context". This is what they mean by "context" : each of those little white tags labels a "context" - a bed of sediment whose relative date (compared to other contexts) can be determined by the "A-overlays-B" and "C-cuts-across-D" arguments of stratigraphy. It's bread and butter work to an archaeologist (and I'm up to the eyeballs in the same sort of work drilling my oil wells), but it's absolutely essential to getting a proper understanding of a site (or oil well). And with it, we can do things like this :
 These are wooden fragments, possibly from a turned or carved bowl, taken from one of the "contexts in the image above. They're large enough to probably give a good carbon date to the context from which they come. AND thereby, they constrain the possible dates for many of the other contexts on the site.
Then along comes some creationist dipshit and dismisses this sort of work with "the archaeologists are lieing bastards who are blinded by their science to the power of our great sky fairy". Well, fuck you, god-squaddies - you plainly do not understand just how much hard, painstaking, detailed work you are casually brushing aside just to make yourselves feel less insignificant than you are.
These dingbats really do make me seethe.

To de-seethe, another bit of Skye's improbable scenery. The Old Man of Storr. See it before it falls over!
 There's a famous fossil site near the Old Man. It's a "no hammer" zone, but that doesn't preclude one finding excellent fossils in the beach debris. However ... when the site says "check the tide tables", it means "do not turn up on a whim without the slightest idea of the state of the tide". consider yourselves warned.
Lybster oil drilling site. There's an oil well of considerable weirdness being drilled there. The interest and amusement are pretty esoteric though.


Diving in Benin

I'm trying to gather contacts about doing some diving in Benin. Same sort of deal as when I was in Tanzania last year, operations will give me a few days break in town.
There doesn't seem to be a lot of info. An article in Africandiver.Com from 2009 refers to a commercial diving operation in Cotonou harbour, which doesn't surprise me in the slightest. I'm following that up.
Another blog posts about diving with the same people in 2012 ... actually at about the same time that I was at ECO2 in Tanzania. And I'm following that up too.
Going from a visitor every 3 years, to one a year may not be exactly a thriving business opportunity, but it's also several hundreds of percent growth.

UPDATE : I eventually contacted the company, but he was very busy with regular diving work in Cotonou harbour, with no time or interest in providing fills or gear for amateur visitors.


Partial Solar Eclipse 2013-11-03 13:25 UTC

I'm back on a rig, for a different bunch to the previous people in Tanzania (who are continuing with their programme there).
This time I'm on the West coast of Africa. Several tens of miles off the coast, actually. This map shows (approximately) where. The boats are not exactly un-obvious, but there's no point in making the pirate's lives any the easier.

Google Map

Today, in between doing things in the office, we've had a bit of post-prandial (after eating, for those who don't speak "Classics") excitement trying to follow a partial solar eclipse. We're actually several hundred miles from the totality region (which made landfall in Gabon, between Port Gentil and Libreville), so we only got a partial eclipse, but it was still pretty damned good.
Unfortunately, I'd not done my homework, and so hadn't brought decent filtering equipment for solar photography with me. Mea culpa. So I had to bash together a filter to protect (one) eye, and the sensor of my camera. Sometimes the warnings about "eclipse eye safety" are a bit overblown, but it is true that you can hurt yourself, so a reasonable degree of precaution is sensible. (And apply rule #1 : if it hurts, stop doing it!)
So ... what had I got? The black rubbish bin liners on the rig ... are too opaque and the plastic is loaded with biodegradable starch grains, so they're no use as filters. (Pure plastic sheeting, if thin enough, can do a reasonable job, and you can stack layers to adjust the dimming. It's a bodge, and only a poor substitute for a proper filter. As you'll see.)
Then I realised that I'd got a pair of those cardboard "spectacles" for viewing "3d pictures" with.
Now, those filters by themselves don't do a lot of filtering - maybe a stop or two (transmitting a third to a half of the light falling on them). But they're complementary colours :
So the combination is much darker - 6 or possibly even 8 stops (transmitting a tenth to a twentieth of the light incident on them). It does impart a rather unhealthy hue to the photos, but it got the light into the right sort of range of intensity that the camera's auto-exposure could handle it. With a little help from being set into low-sensitivity mode by the user. (Yes, I did RTFM.)
So, results :
Lesson # 1 : flash is a waste of battery in these circumstances. And it's still (just) too bright. By eye I can see the bite out of the Solar disc, but it's washed out in the sensor. On the other hand, the sensor hasn't started streaking (charge leaking from one CCD cell to the adjacent ones, resulting in vertical or horizontal (depending on the wiring of the sensor) streaks of overexposure).
The netting around the helideck is obvious, and those blobs of cloud promise considerable dimming of the light as they pass across the Solar disc.

My next attempt to handle the overexposure : prop myself up against a convenient piece of metalwork, and zoom the telephoto lens to it's maximum. (It is left as an exercise for the reader to realise why I didn't bother trying to use the additional "digital zoom" in the camera.) It didn't really help much. The cloud probably helped more.
This is the same image, but with the contrast cranked up all the way, and the brightness scaled back to reveal the top couple of bits of the intensity range. The zone of most over-saturation is noticeably off-circular, and that is in approximately the correct orientation for the "bite" that the Moon was taking out of the Sun's disc. All I need is another stop or two.
The moral of this story : carry your bloody filters! I'm there in a technical sense, just. But, to be honest, the photos are crap.
So what else can I do? Wait for cloud. Take some photos of our little flotilla out here.Look to see if we can see the shadow bands of the totality away to the south.
Oh, look. Cloud!
And the cloud is dialling the exposure down.

I processed this image (offline ; you don't have time to do this in the real world. You do your exposure calculations in your head.) in exactly the same way as the previous one (contrast up by 127 bits ; brightness down by 126 bits) and even the eye of faith isn't needed, because there's clear evidence of the wolf Fenrir attacking the Sun.
And the cloud thickens more.And off comes the makeshift filter.
Time to blow trumpets and bong gongs to scare the wolf away!

Not the best photography in the world, but not too shabby for stuff scrabbled together at the last moment.


Strange thing on Mars

As you do, I was browsing the maps of Mars on Google last night (, as if you didn't know already) when I wandered across this odd feature
SW of Olympus Mons on Mars (use the "Visible" band of imagery). 

(Unlike Google's terrestrial mapping, the option to embed a map isn't provided, so here's a static screenshot.)
What is attracting my attention is the linear feature across the centre of the image. It's approximately radial to Olympus Mons.
It's coordinates are  Lat +17.486911 & Long -143.34960.

So, WTF is it?

Checking the Gazetteer of Planetary Nomenclature, I can't find anything listed with a formal name at (vaguely) those coordinates. The range of possibilities includes (sorted by latitude) 
Name                                               Diameter          Latitude             Longitude -->
10.16 17.28 226.6
6.68 17.31 108.11
19.65 17.37 321.42
11.26 17.41 329.74
5 17.51 329.29
8.47 17.55 321.24
24.74 17.65 111.03
(Sorted by longitude.) -->
51.1 77.17 214.24
Lycus Sulci
1350.61 28.14 215.53
Gordii Dorsum
481.56 4.11 215.86
Amazonis Sulci
250.59 -2.15 216.29
296.67 -29.56 218.46
74.63 -49.92 219.58
(Note : the gazetteer uses a 0-360 range for longitude; -143 = 143 W = 216 E)

A reality check : am I looking at the correct regions? "Pangboche" is a feature on Olympus Mons  (named for a Tibetan monastery on the approach march to Mt Everest base camp). "Lycus Sulci" is an albedo feature spreading around the west and north-west of Olympus Mons. So, I pass the reality check, and I'm looing at the right ranges of names.
No matches. So no-one has given it a name previously.

 The next of NASA's suggested resources is  Map-a-planet : what can that tell me?
Well, the MOLA (Mars Observer Laser Altimeter) dataset indicates that this feature forms a modest topographic low. And the feature is visible in the other base maps too, which is a good sign (not an observing artefact then).
Moving on then to the USGS's Mars Geographical Information System (GIS) at Mars Global GIS I can check dimensions : it's about 140km long. Which is not unreasonable for a large dyke system (but I'm hypothesising ahead of data). 

There are also a number of other sub-parallel features in the topography and basemap data.

Well, that's where I am at the moment. There's a real feature there, but what it is ... I don't know. I can't find any names in the region, which suggests that it hasn't received too much specific attention. And I'll continue later. 
Continuing research ... Searching Google for related terms ... 
ESA have been looking at the O.M. aureole. Not in this exact area, but close (222° East and 22°North). See ... pretties, but concentrated on landslip deposits to N and slightly E of my target location.
Searching for "mars olympus mons linear feature" ... discusses the origin of the aureole, including evidence for slump faulting in the area. Not (particularly relevant). gives an overview of volcanism on Mars, but nothing specific for this region."These features possess very narrow (~35 – 45 m) crestal axes, are more resistant to erosion than the adjacent terrain, show a lack of stratigraphy in their vertical faces, and have a “meandering” strike consistent with the characteristics of terrestrial dikes. Inspection of Viking Orbiter images suggests that some dike segments may be 100 – 150 km long, with maximum lengths >300 km." This study certainly shows dykes and they're in the appropriate area and scale. Includes mention of possible dyke interactions with groundwater leading to pyroclastics / phreatomagmatic eruptions. Which might give the colour changes.
 (file saved locally as "fifthcon99-6050.pdf") Some of these "pyroclastics" overlie lava flow edges. discusses aspects of the photographic interpretation of the landscape.
(Page 3 of this Google search ... and I'm being self-referential!
Sixth International Conference on Mars (2003) 3149.pdf : looks at debris glaciers - interesting, but not relevant.
Icarus 181 (2006) 388–407 : looking at more piedmont glaciation. Which is good,but is to the N of the area I'm interested in.

2012-11-22 07:00
Woke up and thought of "HiRISE swathes". Checked phone to find that @doug_ellison (one of the @marsroverdriver crew) was suggesting particular swathes. are the (shortened links) to swathes he mentions. (Side issue - why didn't this tweet appear in the computer feed, but is on my phone ... meh!)
Swathe 1, decodes to "", where "chriso" discusses that the "dark spots" appear to be in contrast to the general ground lightness, which is ascribes to the general ground being mantled by light-coloured dust while the dark spots have relatively dark "basaltic sand". (This gels quite well with what we saw a couple of years ago on holiday to Santorini, with some beaches being of "black sand" and others of creamy-white pumice fragments. There's more going on there than grain size and chemistry, but that's good enough for this range of viewing.) There are certainly variations in the intensity of the blue colour, which would look like a variation in the amount of light dust present (or in the effectiveness of dust removal - in this view, it looks more like a deflation basin to me, perhaps. I'm looking very much at the blue patch between the central pinnacle and the main hill, and at the area just west of the main hill.). "chriso" describes alternating layers of dark and light material, but only in the darker areas ; maybe s/he's looking at higher resolution data, but I can clearly see three light-dark alternations south form the central pinnacle, which extend towards the east of the shot. (I'm assuming, perhaps wrongly, that the image is displayed in north-is-up orientation. EDIT : that's confirmed by the footer metadata - N=up.) The footer also includes a context shot from MOLA imagery, which puts this at the West end of the chain of dark spots.
Oh, hang on - that top-of-the-page image isn't the science image ; that's hidden in the background which links to PSP_009502_1980_RED.browse.jpg (naming convention PSP = tool name? ; orbit number ; image number?) So, moving back on to the science image ... OK, now I see the "headline" image in the science image, and NOW I can see that the light-dark banding is more-or-less confined to the darker areas (it looks rather like Moire fringing to me - and looks like the light-dark banding is shallow-dipping undulating layering irregularly dissected). The appearance of a deflation area is enhanced, with deflation stronger around particular peaks, and particularly to the W/ NW of the peaks.

Swathe 2, decodes to ""
(OK, straight to the science image! PSP_003450_1975_RED.browse.jpg)
Oh yes, now that I've got my eye in, that's looking very deflationary  also the "Moire fringe" pattern of the light-dark alternations.

OK ; I'm convinced now that these are essentially "deflation features". With access to the HiRISE images, it's quite clear.
This still leaves the question of why it's particularly in this area that it's happening. I'm going to guess that there's a regular wind pattern here (there's a topographic feature associated). Perhaps katabatic winds descending off O.M. with some topographic channelling.

Looking at the raw HiRISE data. (Well, not RAW raw, but the RDR data set (flat-fielded and stitched together, maybe rotated to North-is-up too.) At 341MB for a randomly selected file, I think that I need to be a touch more selective.
Are there mirrors nearer than Arizona?

So, I've been bimbling around for a bit, not really sure what I'm looking for. But I'm getting closer to a (data) product specification.
Having come across the original interesting feature by browsing on Google Mars, the obvious way to follow up would be a similar graphical interface that would display the footprints of the various imagers (and other data sources - landers) onto the image/ topography base map. Whether the GUI is directly linked to the source data is another issue (lots of different formats, I'll bet), but simply knowing "this area has been imaged by mission X (at time Y)" would narrow down the search space greatly. (which would mean fewer "WTF is that" conversations)
I see that the "submit-a-request" section of the HiRISE site does something along these lines already. ... And that's the only such site that I've found so far. ... OK, got myself an account. So, seeing target suggestions, HiRISE footprints, CTX, CRISM and MOC footprints.
Just as an eyeball ... what's the coverage? MOC, several % ; CRISM another % or so ; CTX is close to 100%, maybe a bit over ; HIRISE another % or so. (These are for the area W of and including OM.) It's a bit slow on the browser, but it tells me WHERE there is data, and the (it's a Google-Maps based tool) annoying little push-pins link to the actual science image (making them not-annoying!)
OK, I can see a (convenient) link to high-res data. And previously I've seen that it is common (required? I wouldn't be surprised) for the source image to be cited in papers based on it ... so my next task would be to collate (and collect, why not?) a list of images over the area of interest, and then search for papers that cite those. Without a science library, I'll have a choice of Google or something else. But that should be sufficient for my purposes.


Calamari-that-steals ; Diving El Condesito (originally "El Condosito")

A comic I read recently had a character described (offstage) as
"calamari-that-steals", which reminded me of this character that I met on a dive last year.
Sepia, cuttlefish, or if you're eating it, calamari, on the wreck of the El Condesito, Tenerife
I have to say that this squid did not exhibit any Sqid-like tendencies and made no attempt at stealing my  wallet. Sam clearly has work to do on Earth, if he can get past the shoot-on-sight orders. (See if this makes no sense. It won't make much sense afterwards, but it's a fun web-comic.)

A few other photos from the same dive series :
Blue-fin damselfish on El Condesito. The reason for the name should be obvious.

Ornate Wrasse, El Condesito. Close up, the patterning on the head makes me try to remember the names of the various bones in the vertebrate skull.

Oksana's photo of the diving conditions from the top of the cliffs. Not the exact location of El Condesito, but representative.

A different dive site, known as "Roncadores del Faro" ; a "Faro" is a lighthouse (think of the Wonder of the Ancient World, the "Pharos of Alexandria", the archetypical lighthouse.) and is very visible above water (what else are lighthouses for?) ; the fish in the picture are "Roncadores".

Some people aren't impressed.

Note on photos : the red splodges spoiling the corners of the pictures are text comments added by my automatic thumbnail-image generator. If for some reason you want the original image (typically 3-5 times the linear resolution, 9-25 times the pixel count, no text), contact me. Deals are possible for commercial use, or if you've got a good enough other reason, then make your case.


A few more Tanzanian Piscines

 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)

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

View Larger Map
And finally, the Fish Market :

View Larger Map
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

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.

View Larger Map
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!

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.