Monday, 26 November 2012

Industrial Structural Geology: Principles, Techniques and Integration

The Geological Society of London organises this week the Industrial Structural Geology: Principles, Techniques and Integration conference, from the 28th to the 30th of November.

A bit late, but if you are around registration is still open. It costs £150 for fellows (£250 for non-members) and £30 for students.

The program is here:

You can find more information at the GeolSoc. I will be there on Wednesday and Friday, if you fancy a drink (or two...)

Friday, 23 November 2012

Undiscovering a ghost island in the Pacific

Geographic exploration of our the lands of our planet is basically done and we can say confidently that there are not major unknown features out there. People still find waterfalls in the Amazon and the Himalayas -vertical features not easily detected with satellite data- , or relatively small rivers in the jungle -streams covered by jungle- but we have such a good coverage of the Earth by many sensors onboard satellites, that we can hardly imagine a team of explorers discovering a new river or an island.

What published yesterday the Guardian is actually quite the opposite: a team of marine scientist in the search of an island that, even though it was mapped in Google Earth as Sandy Island near New Caledonia it didn't really exist. So they undiscovered it!

The team on board the RV Southern Surveyor, led by geologist Maria Seton, from Sidney University, embarked on a voyage to research plate tectonics in that part of the Pacific, and passing near the location of the island, decided to investigate it, as they had found discrepancies about its more essential nature: even though Google Earth spotted it, the island didn't appear on the navigation chart of the vessel and no images of it where available.

What did they found? Nothing.Waters not less shallow than 1300 m and not a single evidence of the presence of the island. Check out the location in this map:

View Larger Map

The article in almighty Wikipedia on the Sandy Island reports that some amateur radio enthusiasts had already "undiscovered" the island in 2000, but the story didn't circulate. In that article also explains that it could be a case of a copyright trap -a cartographic method of introducing deliverated errors in order to detect unauthorised copies of a map-.

Do you know any similar case of copyright traps? I do them sometimes in my geological maps!

By the way, you may not know the story of the Landsat Island, an island not mapped before being observed on Landsat images! 


Monday, 12 November 2012

Isopach maps vs isochore maps

Thickness maps are a fundamental tool in structural geology. They represent thickness variations and thickness trends of a given unit. Isochore and isopach maps are two different types of thickness map. To make it clear from the beginning:

  • An isopach is a line that connects points of equal true thickness (i.e. measured perpendicular to bedding), whereas...
  • an isochore is a line that connects points of equal vertical thickness

Fig. 1.- A constant thickness layer is drilled at different angles by three wells
Figure 1 depicts a perfect cilindrical fold, where the western flank dips more than the eastern flank. Well 1 cuts the yellow bed at a higher angle than well 3, and therefore, the vertical thickness found in well 1 is larger than in well 3. Well 2 cuts the bed where is horizontal, and therefore the vertical thickness equals the real thickness. The real thickness of the yellow bed is constant: 500 m.

If we would do an isopach map of the yellow unit, it would show a constant value of 500 m, because this unit doesn't show any thickness (true) variation... It would be a pretty boring map :-). But it would be telling us quite a lot already; for starting, we could think we are dealing with a parallel fold formed by flexural flow (for example).

Fig. 2-. Isochore map for the yellow unit in figure 1.
Figure 2 shows the isochore map -contours for equal vertical thickness- for the yellow bed depicted in figure 1. Red colour indicates minimum vertical thickness, whilst purple shows maximum value. You can see that it shows what you can see in the cross section: we would measure increasing vertical thickness as we move away from the hinge of the fold, as the dip of the bed increases and therefore we would cut the yellow bed at a higher angles.

We can see that the difference between an isopach map and an isochore map is quite obvious and simple to understand. Unfortunately, some people interchange both terms, and too many times we can see isochore maps refered to as "isopach maps"

If we would get the map from figure 2, and somebody would tell us that this is a isopach map over and anticline, we could wrongly conclude that the real thickness around the hinge line of the fold is smaller than in the flanks, and we would probably think that we have in front of us as growth anticline, for example. 

Another error may come from working with seismic surveys and not realising that if you take a surface representing a top unit, and you substract another surface representing a bottom unit, the result is a isochore map, not a isopach map.

Hence... how many structures have been wrongly studied, how many wells haven't reached a target because somebody used wrong a simple word? Better not even to know it! And this is considering that everytime we read a vertical thickness in a well log the well was actually vertical and not deviated at all. If you take a surface representing a top unit, and you substract another surface representing a bottom unit, the result is a isochore map, not a isopach map.

If you have any question, just ask in the comments. If you have any suggestion for a new article, just let me know. You are also welcomed to write some contribution!

Friday, 9 November 2012

Cosmos and Carl Sagan Day

I was born at the end of the 70's. One of my earliest TV memories is the Olympic Games of Moscow in 1980. I was 3 and I honestly don't remember much about it. But something I clearly remember from my childhood is watching Cosmos, by Carl Sagan.  I don't remember the program itself, because I was probably too young to understand it, but I know I loved it and I loved its music by Vangelis. I remember the excitement in my young minds, probably mixing Cosmos with Galactica or Martian Chronicles!

Years later, as a teenager, I spent a fortune (by my standards!) buying the VHS collection. I watched it so many times that after a couple of years the tapes were broken.

Today would be Sagan's birthday. He was born on a 9th of November. And today, almost 20 years after he died, people celebrate the "Carl Sagan Day". Sagan was the voice of science, the voice of reason and talked about the Universe in a way that it was impossible not to stop to think what a privileged lot of molecules with conscience we are.

Still today, Cosmos has a deep effect on me. It makes me happy to be a scientist and not any other thing. It makes me happy to have spent many nights in the garden looking up to the January sky through my telescope. It also makes me miss people that were around me in the 80's and they are long gone by now. 

Now you can enjoy it directly in YouTube. Show it to your kids if they speak English! I hope they like it as much as I did 30 years ago.

I would like to dedicate this post to my friend Daniel Herrero. He came to my home the day Carl Sagan died, and that was the first thing he told me then. I couldn't believe it, and I later, alone, I cried with the book of Cosmos in my hands. 

Wednesday, 7 November 2012

Festival of Geology 2012, in London

This Saturday, 10th November 2012, will take place in London the "Festival of Geology", organised by the Geologist's Association. It will run from 10.30 in the morning to 4.30 in the afternoon, and apart from exhibitors (minerals, fossils, tools, maps, etc), and a "Discovery Room" with activities for kids, it will include four talks:

11.30-12.15 pm — Professor Paul Bown
Investigating the History of Climates and life through deep sea drilling.

12.30-1.15 pm — Professor Rory Mortimore
Using fossils in construction projects:  London Tunnels to Stonehenge.

2.00-2.45 pm — Professor Iain Stewart
Seismic Faults and Sacred Sanctuaries.

3.00-3.35 pm — Professor Jenny Clack
Populating Romers’ Gap : rebuilding terrestrial ecosystems after the end-Devonian mass extinction.

On Sunday 11th November, the Festival will continue in three fieldtrips:

Professor Joe Cain: Geological Illustrations at Crystal Palace
Diana Clements & Naomi Stevenson: London Walk: Green Park and Hyde Park Corner
Geoff Downer: The Building of Ramsgate and its harbour

If that was not enough, there is also an Amateur Photographic Competition on any geological topic, with a £100 1st Prize, a £50 2nd Prize and a £25 3rd Prize.

Fancy attending, fancy meeting up? Tell me in twitter or through the comments to this article!

For more information, visit the Geologists' Association.

Geological heritage, 0 - Developers, 1

And that is all.

As it have been communicated in the Facebook page of "Save Siccar Point", the planning application for the installation of a waste-water pipeline at Siccar Point has been approved by the local council. If you don't know what is Siccar Point, I know need to say two words: Hutton's Unconformity.

The statement pusblished at "Save Siccar Point" reads as follows:

Unfortunately, the planning application has been approved by the Council Planning Committee.

We called the council last week and were told nothing had been decided and there was no news and that committee meetings are usually at the end of the month. Today we found out the council planning committee met yesterday morning. It all seems a bit suspect and underhand.

They have added a few constrai
nts to the application, but nothing that will now stop the pipeline being built and the effluent being pumped out into the sea just 150m from Siccar Point.

We can't thank people enough for the time and effort put into objecting to this planning application, but at the end of the day the council have ignored all the excellent objections, said the effluent was none of their concern (it was SEPA's) and have effectively used SNH's approval of the application as the reason why they couldn't object.

We're sorry it hasn't turned out differently, but with the application approved there's little that can be done to stop the pipeline being laid.

Human stupidity doesn't have limits.  When we will learn that we cannot afford to destroy geological heritage, like any other natural heritage. It can't be replicated, duplicated, or emulated. Things happen once and only once in nature

Friday, 2 November 2012

Follow me in Twitter

I have been using Twitter for some weeks, and perhaps you would like to follow me.
I am progressively focusing on geology issues and general science, but please be aware that I also write in Spanish and sometimes I write about social and current affairs. My tweet feed is not exclusive for this blog, as I don't see the need of keeping a different account for each website I have! Also, I try to keep a flow of 70/100 tweets per week, which I think is a good number.

If you decide to follow me, ping me and let me know!

Earth literally, a blog by Philip Allen

The first time I learnt about Philip Allen was reading Basin Analysis, which he coathors together with John Allen. This must-have book that any student has used since it appeared some 20 years ago is a solid and strong summary of what we know in terms of basin evolution. I think I consult it twice a week, and we have at home two different editions (first and second editions... I am not aware of a third edition!)

This morning, I got a recommendation in Twitter to follow him. I checked his profile, and found out that he writes a blog:

His blog is a little treasure. Earth literally. The title says all! You will find geology, in the shape of very useful artigles with thoughts from such a great geologist, and you will also find a more literally side of Philip, whose prose is reach, enjoyable and reflect his wide knowledge of many topics.

Well, go and check it out, follow him! You won't regret it.