What changes sea-level?

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Relative sea-level is complicated. It is measured from some fixed point in the sediment pile, not a fixed point in the earth. So if, for example, global sea-level (eustasy) stays constant but there is local subsidence at a fault, say, then we can say that relative sea-level has increased. Another common cause is isostatic rebound during interglacials, causing a fall in relative sea-level and a seaward regression of the coastline. Because the system didn't build out into the sea by itself, this is sometimes called a forced regression. Here's a nice example of a raised beach formed this way, from Langerstone Point, near Prawle in Devon, UK:

Image: Tony Atkin, licensed under CC-BY-SA-2.0. From Wikimedia Commons. 

Two weeks ago I wrote about some of the factors affecting relative sea-level, and the scales on which those processes operate. Before that, I had mentioned my undergraduate fascination with Milankovitch cyclicity and its influence on a range of geological processes. Complexity and interaction were favourite subjects of mine, and I built on this a bit in my graduate studies. To try to visualize some of the connectedness of the controls on sea-level, I drew a geophantasmagram that I still refer to occasionally:

Accommodation refers to the underwater space available for sediment deposition; it is closely related to relative sea-level. The end of the story, at least as far as gross stratigraphy is concerned, is the development of stratigraphic package, like a shelf-edge delta or a submarine fan. Systems tracts is just a jargon term for these packages when they are explicitly related to changes in relative sea-level. 

I am drawn to making diagrams like this; I like mind-maps and other network-like graphs. They help me think about complex systems. But I'm not sure they always help anyone other than the creator; I know I find others' efforts harder to read than my own. But if you have suggestions or improvements to offer, I'd love to hear from you.

News of the week

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Compared to last week, it's been a little quiet, and we've been a little busy (not working, don't worry). Here's a quick round-up of some things that have caught our eye over the last few days. 

Google takes on enterprise GIS

The biggest news from Google for a while: Google Earth Builder. For several years, the Google Earth virtual globe software has brought GIS-type workflows to everyone. It's been downloaded an incredible 700 million times. Now, for a fee, you can upload and manage your own geospatial data, and share custom layers with your organization... in a tool everyone knows already. This is potentially transformative because GIS, however powerful and popular, has yet to really penetrate any organization I've seen, though ESRI's amazing ArcGIS Explorer and ArcGIS Server offerings are gaining traction. It's typically still fairly niche, with a small community of power users, lots of dabblers, and masses of people who have no idea what it is and make maps by annotating JPEGs in PowerPoint. Yes, that is as scary as it sounds.

New geo-tagging camera add-on

Geo-tagging photos isn't new, even phones do it. But professional-grade GIS, with rapid location fixing, accurate altitude and compass functionality, is often quite expensive and/or bulky. A small US company, Eka Designs, has announced a couple of new products to try to change this: FotoSpot, an entry-level model, and FotoMapr, for professionals. These camera add-ons use WiFi, Bluetooth, or cable, to connect to a variety of regular digital cameras, oncluding models from Nikon, Canon, Panasonic, and Ricoh. You might want to upgrade your camera more often than your GPS, so this sort of peripheral might be a good investment if you spend a lot of time in the field. Certainly beats scratching down map coordinates and filenames in the rain. 

New books... a lot of new books

We took a look at Amazon's new geoscience books, and it turns out that books are nowhere near being dead! It's hard to find recent titles because when you sort by date you have to scroll past about 500 books that won't be published for months, years even. But here are some recent additions that caught our eye, in no particular order:

Book Titles: How The Bit After The Colon Is Getting Too Long: Where Will It End?

This regular news feature is for information only. We aren't connected with any of these organizations, and don't necessarily endorse their products or services. 

Best online geological maps

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Fisk map of Mississippi RiverOne of Fisk's beautiful maps of the Mississippi River, near Readland, Arkansas. Click the map to see more detail.Like most earth scientists I know, I love maps. As a child, I pored over the AA Atlas of Britain on long car journeys. As a student, I spent hours making my first geological map. As an orienteer I learned to read maps running through rhododendron bushes in the rain. As a professional geoscientist, my greatest pleasure is still producing a fine map.

When I worked on the McMurray Formation of Alberta, my colleague came across Harold Fisk's incredible maps of the Mississippi River. These maps have to be seen to be believed, and for me they show how far computers have to go before they can be considered to have replaced paper. The effort and commitment is palpable. If I ever produce anything half as beautiful in my career, I will consider myself privileged. Even more marvellously, since they were made by the Army Corps of Engineers, they are all downloadable for free.

This resource made me wonder what other maps are out there on the web. Not surprisingly, there are lots, and some are quite special. Here's a list of my favourites:

No doubt I have missed some. If you have a favourite of your own, please add it to the comments or drop me a line and I'll be happy to post a follow-up.

Shattering shale

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In shale gas exploration, one of the most slippery attributes we are interested in is fracability. The problem is that the rocks we study have different compositions and burial histories, so it's hard to pin down the relative roles of intrinsic rock properties and extrinsic stress states. Glass could be considered an end member for brittleness, and it has fairly uniform elastic parameters and bulk composition (it's amorphous silica). Perhaps we can learn something about the role of stresses by looking more closely at how glass fractures. 

The mechanics of glass can be characterized by two aspects: how it's made, and how it breaks.

Annealed glass is made by pouring molten glass onto a thin sheet of tin. Upon contact, the tin melts allowing for two perfectly smooth and parallel surfaces. The glass is cooled slowly so that stress irregularities dissipate evenly throughout, reducing local weak points. This is ordinary glass, as you might find in a mirror.

Tempered glass is made by heating annealed glass to near its softening point, about 720˚C, and then quickly cooling it by quenching with air jets. The exterior surface shrinks, freezing it into compression, while the soft interior of the glass gets pulled out by tensional forces as it freezes (diagram). 

How glass is made is directly linked to how it breaks. Annealed glass is weaker, and breaks into sparse splinters. The surface of tempered glass is stronger, and when it breaks, it breaks catastrophically; the interior tensional energy releases cracks from the inside out.

A piece of tempered glass is 4-6 times stronger than a piece of annealed glass with the same elastic properties, composition, density and dimensions. This means it looks almost identical but requires much more stress to break. Visually and empirically, it is not easy to tell the difference between annealed and tempered glass. But when you break it, the difference is obvious. So here, for two very brittle materials, with all else being equal, the stress state plays the dominant role in determining the mode of failure.

Because natural permeability is so low in fine grained rocks, production companies induce artificial fractures to connect flow pathways to the wellbore. The more surface area exposed, the more methane will be liberated.

If we are trying to fracture-stimulate shale to get at the molecules trapped inside, we would clearly prefer shale that shatters like tempered glass. The big question is: how do we explore for shale like this?

One approach is to isolate parameters such as natural fractures, anisotropy, pore pressure, composition, and organic content and study their independent effects. In upcoming posts, we'll explore the tools and techniques for measuring these parameters across scale space for characterizing fracability. 

News of the week

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The AAPG Annual Convention and Exhibition was this week in Houston. Several companies took the opportunity to announce news. Here's a quick round-up.

Real time well-site mineralogy

Fugro Robertson, a UK-based subsidiary of Dutch company Fugro, introduced RoqSCAN™, a new well-site tool for real-time mineralogical analysis of cuttings. It seems to be a field-portable version of the same technology as their well-received QEMSCAN® lab-based product. Both systems are based on scanning electron microscope analysis. Exciting to see more quantitative tools for geologists. 

More gear for 3D imaging

Ingrain, the exciting 'digital rock physics lab', have bought another Carl Zeiss microscope. But not just any microscope, the AURIGA Crossbeam FIB/SEM, or focused ion beam and scanning electron microscope. Ion beams are useful because, since ions are relatively massive, they can be used to shave extremely thin layers from a rock. The SEM can build up a 3D image of the rock, as it is progressively ablated in this way. If you have never seen Ingrain's 3D images, check out their website for papers like this one (1MB PDF). Amazing.

New plug-ins for viz tool

TerraSpark Geosciences, Geoff Dorn's spin-off from the University of Colorado at Boulder, make a nice-looking piece of software called Insight Earth®. Based on ARCO/BP-funded technology, it's an integrated seismic interpretation tool that seems to have some interesting functionality (we've never seen it in action though). The news is that the company has signed an agreement with visualization gurus INT to develop plug-ins for Insight Earth. Very cool, but we can't help thinking (dreaming?) as we look around these sites: Why isn't any of this open source? 

LMKR go announcement crazy!

The Dubai-based consulting and software firm pwned AAPG, at least if your yardstick is press releases or social media presence (follow @LMKRNews). They are clearly growing aggressively, having taken on marketing and support of Landmark's very nice GeoGraphix software last fall. Watch out for them! Here's what they had to offer:

  • They are hooking up with Object Reservoir, physicist and Landmark co-founder John Mouton's new company, to deliver new shale gas services 
  • They have acquired Cambridge Petroleum Software's Velocity Manager software, for depth conversion functionality.
  • They are adding Scrybe's weirdly-named Convofy to GeoGraphix. What does that mean? We think this may be the most momentous announcement of the year: they have added social media functionality to an integrated interpretation suite. The platform is fully mobile and supports, among other things, microblogging, document sharing, and commenting. 

Even if you are skeptical about social media, please staunch your inner cynic just for a moment and please watch this video. Think about where this last innovation could lead our notions of teamwork, especially in distributed teams. We are excited!

This regular news feature is for information only. We aren't connected with any of these organizations, and don't necessarily endorse their products or services. 

What is your competitive advantage?

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Fortresses no longer provide a competitive advantage.What gave you an advantage once may no longer be helping you. Fortresses just aren't relevant today. Surami Fortress, Georgia.I've been thinking a lot about openness recently. Open-source software, open publishing, and open data are important themes in science today, but not really in business. I think this is going to change in the coming decade, as open-minded young professionals with openness in their blood infiltrate management. I hope Agile* is part of this shift. 

Years ago, oil companies were closed systems. They had secrets. They had large research divisions, rivalling universities in size and scope. They developed their own technology, wrote their own software. The people who worked in these companies were trained in-house, and had long careers. These companies competed with each other on an every-man-for-himself basis, with little regulatory intervention, and little more than admiration and awe from the general public, just glad for its precious petroleum.

Today's industry, however, does not look like this. The typical medium to large oil company...

  • has a small research division, if it has one at all;
  • lets service companies and universities do its innovation, usually as part of a consortium;
  • does little in-house training, relying instead on universities and external trainers;
  • buys dated, off-the-shelf software;
  • has staff attrition and loyalty problems, with most people staying only a few years;
  • is under substantial regulatory and public scrutiny;
  • has customers who don't want or like their product, but are simply addicted to it.

In this environment the research is shared with competitors, the technology is the same as everyone else's, the employees switch companies regularly, and everything is done under the public's disapproving gaze. It is clear that competitive advantage ain't what it used to be. Yet oil companies are stuck in yesterday's mindset, hiding all their data, software, technology, and ideas, even (especially?) the ones that are generic, or useless, or just wrong. What a waste of energy.

So what is your competitive advantage? In the next post, I'll take a look at what I think sets companies apart, and what I think we can safely share. In the mean time, let us know what you think. 

Scales of sea-level change

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Relative sea-level curve for the PhanerozoicClick to read about sea level on Wikipedia. Image prepared by Robert Rohde and licensed for public use under CC-BY-SA.Sea level changes. It changes all the time, and always has (right). It's well known, and obvious, that levels of glaciation, especially at the polar ice-caps, are important controls on the rate and magnitude of changes in global sea level. Less intuitively, lots of other effects can play a part: changes in mid-ocean ridge spreading rates, the changing shape of the geoid, and local tectonics.

A recent paper in Science by Petersen et al (2010) showed evidence for mantle plumes driving the cyclicity of sedimentary sequences. This would be a fairly local effect, on the order of tens to hundreds of kilometres. This is important because some geologists believe in the global correlatability of these sequences. A fanciful belief in my view—but that's another story.

The paper reminded me of an attempt I once made to catalog the controls on sea level, from long-term global effects like greenhouse–icehouse periods, to short-term local effects like fault movement. I made the table below. I think most of the data, perhaps all of it, were from Emery and Aubrey (1991). It's hard to admit, because I don't feel that old, but this is a rather dated publication now; I think it's solid enough for the sort of high-level overview I am interested in. 

After last week's doodling, the table inspired me to try another scale-space cartoon. I put amplitude on the y-axis, rate on the x-axis. Effects with global reach are in bold, those that are dominantly local are not. The rather lurid colours represent different domains: magmatic, climatic, isostatic, and (in green) 'other'. The categories and the data correspond to the table.
Infographic: scales of sea level changeIt is interesting how many processes are competing for that top right-hand corner: rapid, high-amplitude sea level change. Clearly, those are the processes we care about most as sequence stratigraphers, but also as a society struggling with the consequences of our energy addiction.

References
Emery, K & D Aubrey (1991). Sea-levels, land levels and tide gauges. Springer-Verlag, New York, 237p.
Petersen, K, S Nielsen, O Clausen, R Stephenson & T Gerya (2010). Small-scale mantle convection produces stratigraphic sequences in sedimentary basins. Science 329 (5993) p 827–830, August 2010. DOI: 10.1126/science.1190115

News of the week

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AAPG conference starts on Sunday 

The community of petroleum geoscientists will convene in Houston in a few days for the AAPG 2011 Annual Convention & Exhibition. If any geo-tweeps will be there, spare a thought for those that aren't and update us on the events and happenings with the hashtag #ACE2011. Follow @AAPG_Events or @AAPG on Twitter. Wish we were there!

DownUnder Geosolutions coming up over

Australian based DownUnder GeoSolutions (aka DUG, at DuGeo.com) have recently announced that they will be opening offices in Calgary in May. One of the young entrepreneurs helping build this emerging technology company's was recently featured in Petroleum Exploration Society of Australia's magazine. One to keep an eye on!

CGGV have a new processing centre in Oman

The new CGG Veritas office will focus on onshore seismic acquisition and imaging services for the petroleum industry. The centre will also be hosting a university training facility in partnership with the national energy ministry and other industrial partners. In this regard, CCGV is hoping to help develop highly qualified Omani professionals.

Geoscientists without borders

The April issue of SEG's The Leading Edge features stories of the geoscience community solving global humanitarian problems. The International Symposium on the Application of Geophysics to Engineering and Environmental Problems (SAGEEP) has been formed to tackle everything from natural hazards and environmental awarness issues, to finding scarce freshwater resources in impoverished regions. Read more about how geoscientists are making a positive impact and empowering people through education and technology. Great to see this kind of out-reach.

This regular news feature is for information only. We aren't connected with any of these organizations, and don't necessarily endorse their products or services. 

The scales of geoscience

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Helicopter at Mount St Helens in 2007. Image: USGS.Geoscientists' brains are necessarily helicoptery. They can quickly climb and descend, hover or fly. This ability to zoom in and out, changing scale and range, develops with experience. Thinking and talking about scales, especially those outside your usual realm of thought, are good ways to develop your aptitude and intuition. Intuition especially is bound to the realms of your experience: millimetres to kilometres, seconds to decades. 

Being helicoptery is important because processes can manifest themselves in different ways at different scales. Currents, for example, can result in sorting and rounding of grains, but you can often only see this with a hand-lens (unless the grains are automobiles). The same environment might produce ripples at the centimetre scale, dunes at the decametre scale, channels at the kilometre scale, and an entire fluvial basin at another couple of orders of magnitude beyond that. In moments of true clarity, a geologist might think across 10 or 15 orders of magnitude in one thought, perhaps even more.

A couple of years ago, the brilliant web comic artist xkcd drew a couple of beautiful infographics depicting scale. Entitled height and depth (left), they showed the entire universe in a logarithmic scale space. More recently, a couple of amazing visualizations have offered different visions of the same theme: the wonderful Scale of the Universe, which looks at spatial scale, and the utterly magic ChronoZoom, which does a similar thing with geologic time. Wonderful.

These creations inspired me to try to map geological disciplines onto scale space. You can see how I did below. I do like the idea but I am not very keen on my execution. I think I will add a time dimension and have another go, but I thought I'd share it at this stage. I might even try drawing the next one freehand, but I ain't no Randall Munroe.

I'd be very happy to receive any feedback about improving this, or please post your own attempts!

What's hot in geophysics?

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Two weeks ago I visited Long Beach, California, attending a conference called Mathematical and Computational Issues in the Geosciences, organized by the Society of Industrial and Applied Mathematicians. I wanted to exercise my cross-thinking skills. 

As expected, the week was very educational for me. Well, some of it was. Some of it was like being beaten about the head with a big bag of math. Anyone for quasi-monotone advection? What about semi-implicit, semi-Lagrangian, P-adaptive discontinuous Galerkin methods then?

Notwithstanding my apparent learning disability, I heard about some fascinating new things. Here are three highlights.

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