Monday, November 5, 2012

Accretionary Wedge #52: Dream College Courses - The Dream of Cross-Disciplinary Integration for Subsea

Wow, time flies by almost as quickly as my children seem to be growing up. Yikes! My last post was well over a year ago. I guess that's what happens when life keeps you busy! Today I'm home with a sick little one, so as she is resting I have a little time to catch up on things long neglected.

I saw the invitation for the Accretionary Wedge #52 call for posts, via @shcwright's Vi-Carius Geology Blog. Interesting that Shawn is hosting this month's wedge with this particular topic, as I hail from the same alma mater - UH - and just learned this morning via the @geologydotcom news feed that the University of Houston will be offering a subsea engineering graduate degree and post-baccalaureate certification program in the Fall of next year (2013). The timing for this topic could not be more suitable for my participation.

Offshore explorationists rely heavily on the support of subsea engineering teams to create the solutions to retrieve, preserve, and transport the prized finds of oil, gas, and other sought-after minerals that lie under the ocean floor. It's one thing to find where these precious minerals might be hiding out, it's a whole other issue to make the extraction and transportation of product something that is economically feasible. The geologic processes that shape our ocean floors and control the sedimentation rates and depositional environments are extremely important for subsea development planning. However, the geology is something that can sometimes get lost in some engineering firms who don't understand it or believe that the concerns are outside of their scope. I cringe when I learn that entire field layout concepts may have been designed on a blank white piece of paper, without even a reference to even the coarsest bathymetric contours or general review of the regional geologic setting.

That's where I come in. Sometimes referred to as a Geohazards Specialist, I focus my effort on understanding an area's geologic setting, past and present active processes (as an indicator of potential future processes), and then work with specialists to help quantify potential constraints to development. Responsibilities include geophysical and geotechnical survey design, acquisition and interpretation, 3D and GIS visualization, fault characterization, slope stability analyses, and soils distribution analyses. These are things that consume my work week, month after month. My work is critical for siting subsea structures in areas where potential hazards can be avoided or at least minimized, and where installation and operation activities will be feasible. I provide input such that engineering design is appropriate and if mitigation efforts are needed they can be properly planned.

I work with subsea engineers regularly, interfacing with pipeline design, flow assurance, controls experts, materials and corrosion specialists, subsea hardware and foundation design teams. So, the announcement of the subsea engineering program at UH strikes a chord with me. Not only do I recognize the need for more trained individuals in this field, but I see the local program as a source for potential future interns and co-workers to my company, mentorship opportunities, as well as potential for field trip and lecture collaborations.

So what would I envision as a dream course for UH? I would love to see a program focusing on the geologic considerations to subsea development as part of this new initiative for subsea engineering education. This would need to be a course focused on integrating disciplines. A course that differentiates the different structures that might be installed and their sensitivities. How do factors like seafloor gradient, soils variability or unit thickness impact siting, development options, or foundation design? When is it appropriate to use a suction caisson instead of a driven pile? This would be a course that walks through the various "hazards" or constraints and elaborates on why they constrain, what implications they have on engineering, and what mitigation efforts can be taken. Why should we look at the safety factor of a slope or understand the types of faults, their kinematics, and their activity? The course would provide an introduction to the geophysical and geotechnical inputs and data quality requirements. What types of surveys should be done, what information can be gleaned from the different data sets, and how might the physical handling of soil samples affect laboratory results? The course would walk through basic routing and siting techniques and tools. This is a GIS and how it can help your analyses and data management throughout the development process. The curriculum could also include a segment on regional constraints. For instance, discussion on regulatory requirements that vary across different regions, and implications of design and analysis that result from using various standards and design codes. What constraints are present in the frozen arctic, versus the muddy and salt-tectonic dominated structures of the Gulf of Mexico, versus the seismically active Cypriot Arc or East African Rift, or the textbook examples of massive slope instabilities like the Storegga Slide in the North Sea. Perhaps the course could even incorporate some discussion on corporate cultures regarding risk management. This kind of course could be beneficial to both engineering and geoscience students and professionals and is presently noticeably lacking in the university programs. Maybe it would need to be a multi-course program, in order to cover all the topics sufficiently. That's where I turn it over to get other ideas to sort out the details.

Of course, if a program like that existed I may find myself in greater competition for work. I don't think that would be a bad thing...pushing all of us to be at the top of our game. At the same time, if there were more people who did what I did then my department would be a lot bigger and I'd have a greater potential to delegate work and load balance, which could actually lead to improved long-term work/life balance (if such a thing even exists).  Competing firms could also potentially benefit from the skilled workforce, which would yield more options for services in a capitalistic economy. I believe the overall end-result would be positive for the industry, positive for the professions of engineers and geologists who can successfully integrate, and positive for UH as an education leader.

Tuesday, May 31, 2011

The Glamorous Paleontologist

It has become increasingly apparent to me that children first think of a geologist as one who studies dinosaurs. Paleontologists are the geo-specialists that first capture the minds of our young generation. I have to admit, the dinosaur toys, entire museums, and the complicated-to-pronounce species names are pretty enticing. In our children's eyes, paleontologists are the premier rock stars of the profession.  Maybe I'm a bit jealous.

I visited my daughter's school to talk about being a geologist. The children in that first grade class listened so intently. Geologists study the Earth - whoah!! I'm a marine geologist, so I had a picture of the Gulf of Mexico's seafloor showing the impressive Sigsbee Escarpment and the mini-basin province of the salt domain. We talked about maps - how geologists get to use colored pencils and color on a regular basis. We had recently returned from a family vacation to Big Bend, so my daughter showed her classmates some places we visited on the map. I passed around a Brunton compass so they could feel it in their hands. We talked about earthquakes and volcanoes - things that fascinate kids. I passed around a small mineral kit so they could see how different minerals can look from one to the next. The excitement in their eyes was so rewarding.  Then one child said, "paleontology is cooler than geology". Knife through my heart followed with discussion of how paleontology is a kind of geology.

The elementary school my girls go to has a fundraiser every year coordinated by the PTA that includes a silent auction. Parents and local businesses donate many items for the auction and the school ends up raising more than $60k each year to put back into the school's equipment, teacher certification programs, and playground maintenance. I was thrilled to see that even geology was represented in the auction, with not one but two mineral kits and books. These kits were amidst other auction items such as spa vacation packages, photo sessions with a local famed photographer, the tower of Webkinz, the ultimate BBQ grilling supplies package, and the kindergarteners' handmade pottery, among other things. Maybe I shouldn't be surprised these items pulled in a nice price, with starting bid of $25 and follow-up bids that filled the page. But I am surprised - a pleasant kind of surprise!!

A similar sense of surprise and giddy pride came when I received our copy of the first grade class book. The students of my daughter's class each wrote a short paragraph about what they want to be when they grow up. Each entry was accompanied by a drawing from the child illustrating their dreams of future careers. The entire collection was professionally bound in hardback with the cover illustration drawn by the class teacher. 
Some children wanted to be doctors, one wanted to be a dog trainer, another a soccer star. My daughter wants to be a singer/song-writer, like Katy Perry or John Lennon. The big surprise: Two of her classmates wrote of being future paleontologists! Two kids in one class of 20. 

While I don't know the specific statistics for first grader's wanting to be any kind of geologist, it seems 10% is a surprisingly impressive number. Notice, though, that we're back to paleontology again. Yet, enrollment in college geology programs has been relatively low, with some schools offering no geology program at all and some cancelling their field programs because of lack of interest or funding. And paleontologists are some of the rarest of the bunch.

So how do these kids go from being so gung-ho about geology to pursuing completely different interests in their adulthood? My guess is that the sparkle wears off. Perhaps playing with dinosaurs is seen as a childhood fantasy that gets outgrown like Andy outgrew Woody and Buzz.

I think that educators (and influential geo-parents, mentors, and career-day volunteeers) should find a way to cross the dinosaur adventures with other forms of geology so that if/when the interest in dinosaurs fades that geology can still be a viable, interesting, and exciting field to work in. We need geologists now and in the future, so go forth and inspire!

I'll leave you with this fun, catchy video that was shared on Twitter this past week. "I am a Paleontologist" by They Might Be Giants with Danny Weinkauf, part of the "Here Comes Science" set from the band available through iTunes.    
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Thursday, May 26, 2011

Mineralogy Surrounds You

Mineralogy surrounds you. From mica flakes in your shimmery makeup, to granite countertops and slate floors, to the chalk in the classroom and graphite in pencils. You don't have to understand where it all came from or how it got to you as a consumer to make use of it, but these things are ever so easy to take for granted.  Someone had to recognize the value of the rocks and minerals and have the know-how to change them into something useful.

I mentioned in my last post, that there was a fire in my home. Never did I imagine that the fire in my house would lead me down a path to understand and appreciate the properties of gypsum.  But it did.

Gypsum is an evaporite mineral made of calcium sulfate dihydrate, (CaSO4·2H2O).  A Google search on gypsum will lead you to lots of online resources to learn more about the mineral. It has a multitude of uses, including Plaster of Paris and it is also a major constituent in a product of prime interest to me: Sheetrock.

So let's walk down the path that led to this interest in gypsum and see what we can learn.

It was a cold, late afternoon in January. We went grocery shopping, came home, hastily unloaded the car, then headed back out to take care of other errands before the shops closed for the evening. We came home from our errands, maybe 30 minutes later, to find the house on fire.

From the exterior there were no signs of problem until we opened the door and smoke came pouring out. My husband grabbed the emergency fire extinguisher we kept in our garage to try and help, but heavy smoke prevented him from getting anywhere close to the fire. He also noted that the floor was wet. Of course, we immediately called 911 and thanked God that everyone was safely out of harm's way. We waited across the street as five ladder trucks responded to the call, neighbors came out of their homes from blocks away, and my children clung onto my legs desperately wanting everything to be ok.

My mind raced back to our quick unloading of groceries just earlier. What was out of place?? What could have started this fire? We weren't cooking or burning candles. Was there bad wiring somewhere? Did we have an issue with our space heater in the bathroom - I thought it was turned off? And why is the floor all wet?

The fire department had to use the fire hose to put the fire out. I was impressed that they took care in the process to remove pictures from the walls, pull all the furniture into the center of the rooms, and cover them with a water and fire-proof tarp. Afterwards, they opened all the windows in the home and set up large fans to blow out the remnant heat and smoke.  The fire inspector then went in to analyze the scene.

My 7-year-old's letter to the Firemen

Turns out, large box placed on electric stove top = very bad news. Apparently, one of the burners was turned on by the box that was quickly placed and pushed on top. I hate that I now serve as the example for company safety moments. Lesson definitely learned!!

Our home was found to be structurally sound and was released back to us that night. The insurance company classifies it as a "partial loss".  We are very fortunate. However, the house was in no condition for us to live in.  Smoke and soot permeated into EVERYTHING.  The entire downstairs floor was completely saturated with water. The fire melted a water pipe in the second story subfloor, which poured water out (actually acting like a mini-sprinkler) and flooded the first floor, well before the firemen came in with the water hose.  Upstairs, even though the fire had not actually spread that far, the heat that was trapped up there melted all the feaux wood blinds and the plastic AC registers in the ceiling.  The AC control box, doorbell, and even the smoke detectors were warped and melted.  My daughters' dolls and plastic toys were sticky and soot-covered. The walls in all the rooms, save the far-end of the downstairs, had heavier soot along the joists and nailheads, a kind of ghosting effect.  I learned this happens because the soot tends to settle on areas that are cooler.  It all comes down to the physics of heat transfer. (Here's a little pdf write-up by Mr. Fix-It, Tom Feiza, describing the phenomenon.)

Obviously there is much remediation to be done. Here begins the battle with our home insurance provider regarding what needs to be replaced/repaired, and what is covered by our policy.  Several experienced restoration contractors commented that the sheetrock in most of the house needs to be replaced.  Even the city inspector commented that the sheetrock had obviously been baked. The initial proposal from the structural adjustor: clean, seal, and paint.  !!!

Let's examine the role of sheetrock, or gypsum wallboard, in a home. Obviously, it forms the walls and ceilings of the interior of the home. It is the surface that can be painted over, textured, or wallpapered. It is the surface you drill or hammer into when you want to secure a picture, a shelf, decorations, etc. The sheetrock hides the internal "guts" of your home: the electrical, the plumbing, the insulation, the framework that holds the whole thing together. From that perspective, the sheetrock is functioning as a superficial component of the home.  To clean, seal, and paint the wallboard would only address that superficial issue.

But sheetrock plays an even more important role in your home: it serves as a fire barrier.  Gypsum is a hydrated form of calcium sulfate and inherently contains water within its crystal structure. With exposure to elevated temperatures the gypsum undergoes changes, referred to as "calcination", where the bound water evaporates.  The dehydration process begins when exposed to temperatures in excess of 80°C (176°F). Gypsum becomes calcium sulfate hemihydrate when exposed to temperatures of ~100°C (212°F), which then changes to anhydrous calcium sulfate at temperatures of ~180°C (356°F). Exposure to high heat results in loss of mass and decreasing density of the sheetrock, making the wallboard brittle and crumbly.  Discussion of this process is described in this pdf article by Kennedy et al., 2003. The evaporation of water from the gypsum wallboard is what buys you time in a fire and slows the spread of the fire from room to room.

In my quest to "prove" to the insurance company that the sheetrock in my home would not be "pre-loss" condition if simply cleaned, sealed, and painted, I stumbled across a very interesting and insightful article in the Journal of Fire Sciences.  The article by Melinge et al., (2010) describes the discrete mineralogical phase changes that occur over time during exposure to high heat.  Their laboratory analysis involved exposing a very thick piece of gypsum wallboard (40 mm) to high heat over time and documenting the incremental changes to the mineralogy as the calcination process occurs. What is very interesting about their study, is that they were able to document the exposure length of time and temperature and its relationship to the gypsum wallboard across its cross-section.  They could record the phase changes as they occurred on the heat-exposed surface of the wall board and then observed as those changes migrated through the wallboard. Their work showed that alterations of the gypsum board due to exposure to high heat is dependent on the thickness of the gypsum board, the temperature of the fire, and the length of exposure time.

We cut samples of the sheetrock to send off for testing, one from the second story ceiling that was exposed to high heat and another from the lower floor on the far end of the home not exposed to the heat. There were very obvious differences in the material as the samples were cut.  The sample from the ceiling had very irregular edges and was crumblier, although only through about half the thickness of the sample. The piece cut from an unexposed portion of the house had smooth edges and no obvious issues. Moisture testing of sheetrock samples from the heat-exposed ceiling in my home yielded a 8% decrease in water content compared to the sample from an unaffected portion of the home.  It was interesting to find that the same methods for obtaining geotechnical moisture measurements in soils are used to evaluate the moisture content of the sheetrock.  The only difference is that they have to heat the sample more slowly than a typical soil sample so as not to initiate the calcination stage too early. 

It took us over a month to come to a consensus with the insurance company regarding the sheetrock. The insurance company finally agreed to change out 60% of the sheetrock.  We are paying our contractor to remove and replace the other 40% out of our own pocket. In the end, I think they ignored the science and opted to concede only because our alternate living expenses were adding up.  I learned, however, that the sheetrock does more for you than just look nice. If we are unfortunate enough to have to go through this again, I want the peace of mind that any loss was not due to reduced fire retardancy of our walls.

Yay for calcium sulfate dihydrate!!

Wednesday, May 25, 2011

Quick Update

I just wanted to give a quick update to let everyone know I haven't fallen off the face of the Earth (yet). I was sucked into some very intense project work for a while that pretty much demanded all of my time and then some. In addition, my family was unfortunate enough to have experienced a kitchen fire back in January, which forced us out of our home as we try to rebuild. I have since taken a self-imposed hiatus following on my resignation from the consulting company I was working for, with plans in the works to try and start a new chapter of my career in July. I will keep you posted!

So, with some newfound freedom and time on my hands I'll be trying to squeeze in some blogging time between kids' activities and trips to the home improvement store and calls to our insurance adjustors. In the meantime, I have updated my sidebar widgets (now ad-free, yippee!) to include my Twitter feed and also updated my blog-roll (about time, I know). I am looking into a mobile app for the HGS to provide easy access to event info, social media updates, and geojob bank postings for smart phone users (both for iPhone and Droids). We'll see if things come together or not!

Sunday, July 25, 2010

A neoGeo-blogger's View of the Geoblogosphere

I just realized that this blog has been up for over a year now.  I haven't been quite as active at blogging as I hoped I might be, but it has been a fun experience to frame up my thoughts, work through the writer's block, and connect with the vast online community.  To celebrate this belated anniversary, I'm jumping into my first official contribution to The Accretionary Wedge blog carnival.

For those unfamiliar with a blog carnival, it's a collection of blogs centered around a specified topic, collected and presented via permalink by a hosting blogger.  The Accretionary Wedge carnival is hosted by a different blogger of the online geo-community every month and solicits entries covering a myriad of geoscience-related topics throughout the year.   This month's theme was derived by Dave Bressan thru his musings with Michael Welland, and resulted in a call for posts that appeared on Dave's blog, The History of Geology.  The question: the role of the geoblogosphere in geology...
The Geoblogosphere comprises and gathers every day the newest articles from more then 200 blogs (and still counting) dealing with the most various earth related themes, ranging from geological excursions, sharing field experiences, philosophizing about earth sciences, life and art, media coverage and daily rock encounters to discussion of the newest scientific discoveries on this planet and others. So philosophizing around (geo)blogging with Dr. Welland many questions raised:
- like how bloggeology can “impact” society and “real geology,” should and can we promote the “geoblogosphere,” and are blogs private “business” or public affairs, and institutions underevaluating the possibilities given by this new method of communication?

This topic resonates with me, even though I am a neoGeo-blogger.  There are many facets to the questions posed so it will be difficult for me to put all my thoughts out on the figurative table.  But I'll try anyway.  

Before I can fully address the role I see for blog-geology, I probably should first explain why I blog and what I hope to gain from it.  Then I should define what the "geoblogosphere" means to me.  

It all started for me with Twitter.  As an amateur webmaster (I designed and currently maintain my company's website and host a php-based message board) and as the spouse to a mega-techie-junkie, tinkering in things like social media are fun little hobbies for me to play with in my spare time. I must pick up some techie-ness via osmosis or something - father and husband both engineers.  Anyway, after hearing friends talk of Twitter I scoped it out, was immediately intrigued, and set out to see what might come from the tweets of mine and the twitter-ers I started to follow.  What an amazing group of geo-tweeps I stumbled upon!  Their posts regarding field trips, research, public policy, news, myths and misconceptions, frustrations, industry events, educational opportunities, and social commentary has been a major inspiration for me.  All of you that I follow - yes, all of you - are awesome.  \m/(>.<)\m/

I started this blog on a late Tuesday night in June, 2009, with overly idealistic goals to share my geologic knowledge and stretch my writing wings a little bit.  I wanted to be a contributing member of the geoblogosphere, because the rest of you are so darn cool.  However, throughout this year I struggled to meet my own expectations for what I wanted this blog to be.  Time constraints played a big role in my blog-ability (working 60+ hour weeks with 3 kids under 10 at home makes for some rocky times),  but the main reason I struggled is because the geology that I know the most about comes from my work experiences, which falls under strict client confidentiality agreements.  All the data I have access to, the interpretations that come together, and the development of geological models are the property of my clients and the survey companies that lease the data to them.  Working in frontier deepwater oil and gas exploration is fascinating stuff, but most of what I do is not in the public domain.  I find that leaves me very little of my own material to present and discuss with any true depth.  The result has been a great learning experience for me to dig deeper into myself to discover something worth sharing or applicable to others  even when stripped down to generics.  I am honored and grateful to have lured anyone into the blog for a short visit, much less a regular follower.   So, big-time thanks if you are still reading this.  :)  I hope that as my geo-blogging experience grows I will find interesting topics to share and the writer's block a little easier to combat.

So what constitutes the geoblogosphere? I define it as the collective geoscience communication network developed via various internet-based utilities, be they formal blogs, social micro-blogs such as Twitter or Facebook, or other academia, industry, or research-based websites.  Just as the many specialties in geology diverge and converge, so do the ways in which geology can be communicated. Members of the geoblogosphere constitute individuals - professionals, students, interested non-professionals, educators, policy makers - as well as corporations, government entities, industry societies, and research groups.  

Institute of Geosciences of the Universidade F...Image via Wikipedia

Back to the main question: what do I perceive to be the role of the geoblogosphere?  For me it is about community.  It is the community that drew me in, educates me, challenges me, and inspires me.  Asking what the role of the geoblogosphere might be is really asking what is the role each of us plays in our community.  Like any real-life community there are a number of roles to be filled: educator, protector, entertainer, supplier, etc.  The geoblogosphere serves all of these things for the geoscience community in some capacity or the other.   Most, if not all of which, have plenty of room and need to grow.

Members of the geoblogosphere educate each other, educate the public, and maybe are educators by profession.  The same can be said for protecting, entertaining, and supplying.  Granted, since there is no self-proclaimed internet police validating the facts shared online, the value of the material presented via the geoblogosphere and elsewhere should be weighed before presuming things as the God's honest truth.  Then again, value depends on who is doing the valuation.  From what I have witnessed, we do a pretty good job of policing each other, QC-ing content and peer-reviewing, although via less formal means than maybe traditional.

In terms of "real geology" I am awestruck by the level of camaraderie and openness that exists in the geoblogosphere and how it allows for communication of real geologic wonderment.  The vast expanse of specialties, geographic representations, and experience available at your fingertips as part of the geoblogosphere is unfathomable.  True geology is shared en masse and those of us with desk jobs in cube farms bask in the joys shared by the offshore and overseas bloggers, the field geologists, and the twittering TA's.  Perhaps the reverse is true, as the field geos are fighting off the cactus and the mosquitos.  The opportunity to learn, share, and experience things beyond your own surroundings is a rich opportunity that shouldn't be skipped.

The value of the geoblogosphere is greatly unrealized by those who are not a part of it.  Although I still consider myself new to the geoblogging community, I strongly promote participation in the geoblogosphere, as I believe it provides a win-win for everyone involved.  The community benefits through a diversified membership base, and the members benefit from the various services offered by the other members, the geoblogosphere as a whole.  

In my professional life I have followed up on references, news, and research I stumble upon through the geoblogosphere that directly contributes to my project work or  introduce alternate hypotheses.  I am enlightened and aware of things outside my specialty that I otherwise would never be exposed to.  I have the opportunity to see points of view from all sides of an issue.  I don't expect my blogging, tweeting, or status updates to return any tangible benefits for myself, other than the satisfaction of sharing experiences or perhaps someday adding to someone else's inspiration.   I promote the geoblogosphere to my peers and fellow Houston Geological Society (HGS) members by maintaining an online message board (, a Facebook page (, and a Twitter account (@HouGeoSoc) for the HGS, in the hopes that they will benefit as I have from these things.  The challenge is educating people how to use these tools, using the tools to their strengths, and maintaining the momentum to keep it all updated. (BTW, I'm looking for volunteers to join the HGS Social Media Committee, if you're interested).  It is a worthwhile cause to connect with people, connect them to others, and to see growth resulting from that connection.  It is something I am strongly passionate about and enjoy being a part of.  

Saturday, June 26, 2010

Geocaching and the SillyBandits

I've heard of geocaching before and thought it sounded cool, but not something I had time to do. Prior to the days of iPhone ownership, a GPS wasn't something I had handy all the time. Well, times have changed, my friends, and GPS devices are pretty much are the caches.

For those unfamiliar, geocaching is like a go-at-your-own-pace treasure hunt. There's an entire community of geocachers out there who hide (and seek) multitudes of goodies. Some cachers are pretty hard-core trying their best to be the FTF (first-to-find). But some caches have been around for years and scanning through the log books can be an awe-striking moment. Micros are pretty small - usually only consisting of a log to keep record of the finders. The most common, traditional caches, are ammo boxes, just large enough to hold a log book, and a few relatively inexpensive trinkets. The thrill is in the adventure of finding the hidden caches, learning about the community around you, and tracking items (like geo-coins that are moved from cache to cache) around the world.

For more info on geocaching or what caches are near you, check out and get started!

My family has been bitten by the geocaching bug. My older daughters (ages 8 and 6) are enthralled with the adventure of looking for a treasure, a welcomed motivator to get them outdoors. We ventured out for the afternoon and made four finds, each one with their own personality. We had some pretty cool eureka moments, all shared together, for no out-of-pocket expense. Compared to a family night at the movies, with tickets and snacks upward of $60 and the lot of us staring off at a movie screen, I'd say geocaching is a win-win for the family and the pocketbook!

As we dive into this family adventure we are learning some of the geocaching etiquette that keeps the game moving along. Obvious things like paying attention to your surroundings, not drawing attention to the cache location (beware of "muggles"), and programs like "Cache in, Trash out" are important mindsets that allow geocaching to work. A nice listing of geocaching pointers are provided HERE, and definitely worth a good read before heading out on your adventures.

My girls have come up with their own geocaching team name - the SillyBandits. They want to leave silly bandz (the many colored, many shaped, over-priced rubber bands) at all the caches they visit. Now when we head out of the house, and across town, we're checking what kind of detours we may make along the way. With an upcoming family vacation, involving driving through multiple states, we are excited see what kind of swag we find, places we visit, and communities we connect with.

Do you geocache? Leave a comment and tell me about your best cache experience or cool swag!

Sunday, June 6, 2010

Down to the Core

I've had the rare priviledge in the course of my project work to be able to truly ground-truth interpretations from seismic data through comparisons with core samples. For onshore projects that may not seem like so much of a priviledge as the norm, but in deepwater environments, the combination of data is much less common, particularly in the early exploration stages of which I'm involved.

I have my interpretation of stratigraphic intervals and the kinds of processes that may be at work based on the regional setting, observed site-specific structures, and by characteristics revealed through various seismic attributes. Then I have core data to add to that interpretation, refining the model of what we think we're seeing. The core data includes various geotechnical properties measured through standard lab tests, such as shear strength, water content, atterberg limits, etc. These lab tests, standard and advanced, are destructive to the sample. For my project we also have a radiocarbon and paleontological dating program planned, to try and understand the depositional rates and timing of events. Selecting the sample locations, considering both time and space (where in the core and from which core), is a critical step towards putting the geologic story back together and involves close inspection of the interpreted seismic data, correlation of geotechnical properties between the physical sample and the geophysical record, and understanding what an age at a particular portion of the core can and can't tell you. Digging out samples for age analysis is obviously destructive to the core also. If you have plans to undergo geotechnical testing, you have to make sure you aren't using material you also want to get an age from. It definitely takes some thinking and planning out.

There are some things that can be done to analyze a core without destroying the sample. A multi-sensor core logger, or MSCL for short, is a tool that allows for geophysical measurements of an unsplit, cylindrical core. Working in the marine environment, we've used MSCL for sub-samples of box cores, as well as gravity cores, piston cores, and jumbo piston cores. Compressional wave (P-wave) transducers allow for velocity measurements of the sediments in the core. Gamma ray attenuation is measured through the core and used to derive sediment density. The labs I've worked with can provide various levels of detail for logging, such as 4 cm samples or higher resolution 2 cm sampling. If the core is later split, or material was sampled from the core ends during acquisition, the densities may be calibrated with the lab measurements taken directly. Velocities and densities also play important roles in how the seismic data behaves, so with the MSCL data, the measured geotechnical properties, and the seismic section you can start to make some correlations. Accurate and precise calibration of the MSCL for your samples and close QA/QC of the data are key to getting the most useful data.

Ultimately, if you want to understand the small-scale features, you have split open the core and take a look at the sediment types and preserved structures. This, too, is a destructive process. Once the core is split, you can't put it back together again.

One of the best things you can do with your split core is to photograph it. As with all geologic-intended photographs you will need something in the photograph to reference for scale. Some people place a measuring tape or ruler along the core edge, others mark directly on the core liner in regularly spaced intervals. In the process of describing your core, you are likely to scrape, smudge, cut, poke, and sub-sample the sediments. You might even taste the sample (Yes, a lot of geologists will taste the dirt). In addition, an open core will dessicate and oxidize much quicker than an un-opened core (even in controlled storage environments), which means color, water content, and other geotechnical characteristics can change. While a core photograph cannot capture the geotechnical properties, it can preserve color and structural relationships to which you can refer to long after your sample has been picked through or discarded. A photograph is an important piece of your compiled data set that may prove useful even beyond its original intended use for your project.

It has been my experience that most labs and researchers rush through the steps of capturing those photos. Some are done with basic point-and-shoot cameras, with little attention to lighting, resolution, or focus. Even photos done meticulously with a high-resolution camera suffer from amateur photographers in control of the picture-taking. My recent project data included high-resolution core photographs taken every 10 cm down the length of the core. A lab technician cropped each image and stitched them together to re-create each core section. The files were 100+MB bitmap images exported out of Adobe Photoshop. The resolution on the images was undeniably good, but most sections were coarsely scraped creating ridges and shadows on the split section, the high water content and lighting caused problematic reflections, and poor light distribution made many of the sections dark and the variable colors difficult to distinguish.

When preparing to photograph your core, there are several things to consider. First, the cores are best viewed in natural light. Flourescent lights tend to add hints of blues to the photo. Incandescent lights tend to add hints of yellow to the photo. Neither are desireable if you want to look at the natural colors. Adjusting the white balance compensates for your light source and allows you to mimic natural sunlight when done correctly. Just a note: Color is not always the best geologic tool in the box, as it can be decieving at times. Be careful with what assumptions you make based solely on color.

Second, you want to look at a fresh surface, which suggests you may need to scrape the sediments exposed in your split core. Scraping the core surface is a delicate procedure. You want to scrape across the core, not down the core. Scraping down the core could contaminate your sample, mixing younger and older sediments as you drag the spatula down the core. Scraping across minimizes that potential, assuming you clean the spatula between each stroke. Many people who scrape a core, particularly if the sediments are soft, mistake the process to be similar to plastering and instead of cleaning the surface to reveal the sediments and structures, they smear the sediments, distorting or disguising the structures. It takes a steady hand and the proper spatula angle to really get it right. Circular polarizing filters can reduce reflectivity of the core surface. Multiple strobes at different angles can minimize or eliminate shadows created by uneven surfaces.

Third, things like focus, scale, and resolution are extremely important. You want to make sure each photo is taken from the same distance with the same focal point. This is true particularly if you plan to stitch the images together. You want to minimize the distortion caused by the camera's perspective view by selecting the right lens, zoom level, and core position. A mounted camera is an absolute necessity, as there is no way anyone can hold the camera still enough or at the appropriate angle for every snapshot. Carefully plan the lighting for the photos and minimize changes in the settings as you are capturing your photos. If you are adjusting things throughout your photo shoot, images you capture at the beginning won't match up well with those you capture at the end. Take a lot of test shots and once you have the settings worked out, then capture your suite of images to preserve your entire data set. When correlating your findings are important for you, you want to make sure you are comparing apples to apples.

So, a few recommendations for those pursuing a core sampling program:
1. Consider MSCL data for your cores, particularly if you have other geophysical data you may be trying to ground-truth.
2. When your core is split, carefully prepare a freshly exposed surface for viewing by meticulous scraping done properly.
3. Train the photographer (or hire a professional) to use the camera and other equipment to its full potential.

You might think these are minor concerns, or that any part-time tech could do this work. But if you were to sit in the core viewing sessions I've had with a room full of geologists and engineers, with nothing but the photos and the seismic sections you would realize how drastically different the interpretations can be based on what you see in the photo. If you never saw the core in person, you might think the reflective streak was a lamination and it's cross-cutting what looks to be other laminations. You may not realize it was caused by irregular scraping and poor lighting conditions. It can make a big difference in your interpretation.

Obviously, you need to take your individual program into account and make decisions about your sampling and testing program that will be suitable for the purposes you need. Your methodology for a single core versus what you may do for hundreds of cores could be drastically different. One thing I believe, though, is that it is worth your effort to do it right and do it well the first time.

If you don't have time to do it right, you must have time to do it again. Only with a core, you usually only get one try.