Friday, December 2, 2016

Titan or Europa?



Here's more of a series of questions by a thoughtful person who meets my definition of a scientist: someone who may not have a degree in science, but constantly wonders about - and studies - the world around her/him. 

Q:  ...as you point out well, our job titles or status titles never will adequately reflect the complexity of the human mind. I appreciate the humble response, because you're right, and I know many individuals that fit your plumber example very well. Intelligence is something that can't be restricted by any persons "title." I didn't mean this response to be so long because I actually had another question!

      So, even though I know geology focuses on earth based phenomena, I have to think you probably have good insights into the first place we might most likely find extraterrestrial life in our solar system. Titan, fitting name, seems to dominate the conversation that I have seen. But this seems much more extreme to life as we know it than something like Europa to me where what I have heard postulated is a possible underwater ocean/theremal vent type scenario where some extremophiles could potentially reside. And that nicely correlates with things we have seen on earth. I have just felt that Europa seems a bit left out, even though extremophiles in methane lakes on Titan is awesome and intriguing.
-Joe A


A: I concur completely: Titan is intriguing, but frozen methane-based life, if it exists, will not be meaningful to carbon-oxygen-water-based life (us) except in the abstract (as in: gee whiz). Europa has all the necessary ingredients: water, complex organic chemistry (clear from the colored streaks on the surface), and heat (the huge tidal gravitational gradient from too-nearby Jupiter). However, if we thought it was expensive and complex to get Curiosity operational on Mars, it will be one or two orders of magnitude more expensive to get something working in (and able to report back from) the ocean beneath the frozen crust of Europa.


Friday, November 4, 2016

Is Our Atmosphere Dynamic?


It may surprise readers to learn that the American Geophysical Union has divisions named Atmospheric and Space Electricity, Global Environmental Change, and Atmospheric Sciences. In short, the geosciences world include a very large element of atmospheric science.  The following query has several different elements, all of which suggest an awareness of how dynamic our atmosphere really is.

Q: Hello. I wasn't sure which category to inquire within but this seemed appropriate. Since Earth is not a perfectly spherical object, nor any other planetary bodies we know of, how does that affect the gaseous layers of atmosphere surrounding us? My question stems from an uneducated assumption that our atmosphere is not a perfect bubble around us but must be dynamic given the amount of energy factors associated with it, the terrain beneath it and which locations have the greatest gravitational pull. Can the sphere of air around us ever dissipate into space? Are there higher or lower points that exist because of geography that make our categories of layers more ambiguous?
-Joe A

A: As you suggest, the atmosphere is indeed a very dynamic thing, and yes all rotating solar system bodies are oblate spheroids because of centrifugal force at the equators (and none at the poles). Jupiter rotates at a phenomenal rate (it has 9.8 hour days!) and is thus is the most oblate planet of all.

If you think about oceans, however (the ocean surface is at the same elevation above the spheroid datum over the Marianas Trench as it is in Pamlico Sound), then mountain ranges will similarly have little to do with atmospheric height over the globe (there IS a small amount of isostacy - high mountains with deep roots that locally distort the acceleration of gravity). The most common exception to this are called storm surges - the low-pressure cores of hurricanes and typhoons will literally lift up the (warmed and expanded) ocean water. With Hurricane Katrina, the storm surge reached an astonishing 8.5 meters (27.8 feet!) at Pass Christian, Mississippi. That's 'WAY above the normal high tide!

There is atmospheric thinning with altitude, however, and the upper reaches can still be detected at 100+ kilometers, which is why satellites must fly at 250+ kilometers. Even at those altitudes there is measurable drag that over time will bring down low-flying satellites and launch vehicle debris. Most of the upper atmospheric variation has to do with solar wind and solar heating activity, however. Because of Earth’s gravity (and to a surprising degree, Earth's magnetic field), most of our original atmosphere remains - unlike Mars, where the original atmosphere and water were stripped over time by solar winds that weren't diverted by a magnetic field. 

When you see clouds over mountain tops (pretty common over our volcanoes in the Pacific Northwest), it is because winds trying to get around the mountain send some of their components up and OVER the mountain. This leads to a drop in temperature with increasing altitude, which contributes to dissolved moisture precipitating out into what we call orographic clouds - cloud caps. As the air moves past and back down to lower elevations the water re-dissolves back into the atmosphere and the trailing edges of the clouds disappear... but the same AMOUNT of water remains in the air.

Q: I had to do a little research to understand a few of the terms you used but I definitely feel like I came away with a better understanding. Thank you for your insightful response. I shouldn't be surprised I guess that avenues of inquiry like this are out there given the ubiquity of websites, but I never tried something like this before. I had a thought, did some googling and found you. It's awesome to get answers from professionals as if I was back in school and could pick the brains of my professors after hours. So thanks again, despite my questions being kind of convoluted!
- Joe

A: I'm glad I could help. I suppose I am technically a professional, in that I get paid to do research in geophysics, but I'm just a very ordinary person with the same level of curiosity that you have. I personally don't divide the world into professional vs. non-professional, but instead into interested vs. non-interested. I plumber who asked some really deep questions about the lithosphere and upper mantle told me he spends a lot of "windshield time" thinking about the physical world as he drives from job to job. 

THAT meets my definition of a scientist. You and I fit in there also. That goes for anyone reading this chapter, too.



Saturday, October 8, 2016

Simple Answers to Complex Problems Are a "Misteak."



This question follows a previous Q&A, so you'll need to read previous chapters to get all of this.

Q: Wow, a lot to un-pack there (by no means a criticism.) In fact, thanks very much for the extensive informative responses!
     My next question (maybe last, if I'm not pushing your patience too much here,) regards the truly catastrophic's.  I'm 29 years old, which can't even be considered a mote in time when considering numbers like 13.7B or 4.5B, but nevertheless, here we are. Growing up it was accepted via the direction of our science teachers that dinosaurs were wiped out by an asteroid, and it seems to make sense. But alternative views like supervalcano's have been touted on science sounding TV channels  as an alternative and I wonder about your thoughts on that. And minus dinosaurs, would we more statistically face worldwide threat from geology, a comet/asteroid, or a biological problem? We can leave out human stupidity towards ourselves for the sake of the argument. I guess cosmic factors too.
--Joe A

A: Most of humanity seems to gravitate towards a simple solution or answer to a complex problem. It's mentally easier. This is really obvious in the current political "debates" going on (Build a wall! Cut taxes! Increase spending on X!). The most difficult scientific problems to solve are the ones with more than one poorly-understood variable. MOST problems have complex causes. If my Microwave stops working, I think oh: it must be the power is out. Closer inspection shows that the power is there. Darn, no simple answer. OK, what's next to check then?

The Chicxulub event certainly had a big impact (pun intended) on saurian life when it hit 66M years ago, but there IS evidence that Life for Large Saurians was getting more and more difficult, with environmental degradation due to several things already underway, including volcanism (it was possibly accelerated by the formation of the Deccan Traps). However, make no mistake: a 2-cm layer of ash full of 1000-times-normal iridium in Gubbio, Italy, came from the Gulf of Mexico. A 10-km-diameter asteroid carries a ginormous amount of kinetic energy with it. The Earth's gravity well is pretty strong (a rock dropped from the Lagrangian point between Earth and Moon reaches about 19 km/second). This is also the speed of a minimum Earth orbit. The Chicxulub object certainly had a much higher velocity than that, and energy is mass times velocity squared. Double the velocity and you quadruple the energy delivered (it's a principle I teach to my Jujitsu students). From several studies there is a consensus that the Chicxulub kinetic energy before atmospheric entry was about 5.4 x 10^23 Joules, or 130,000,000 Megatons of TNT equivalent. By comparison, the largest hydrogen bomb ever detonated (by the Soviets, at Novaya Zemlya) was just 57 Megatons.

Monday, October 3, 2016

When was North Carolina Last Under Water?



We often get queries that ask about local geology that we do not have easy access to. However, it’s fairly easy to sleuth things in the broad brush by locating state geologic maps. I can’t say much about a rock found in someone’s backyard, because glaciers and rivers could have moved that rock hundreds of kilometers from its original source. The following is a local-geology question that I CAN reasonably respond to. 

Q: Can you tell me when was the last time North Carolina was under water? I'm finding fossil seashells yet I live nowhere near any ocean. I live in Jacksonville, NC (Onslow County)
- Brandon F

A: You live on the Outer Coastal Plain of North Carolina; Onslow County runs all the way to the ocean. The Outer Coastal Plain, or Tidewater is extremely flat, averaging less than 20 feet above sea level. It contains large swamps and lakes indicative of poor drainage conditions, which have hosted both freshwater and marine mollusks at different times. The coastal margin north of Cape Lookout is a “drowned coast,” in which sea level rise associated with the end of the last Ice Age, and continual melting of the ice caps, has caused the ocean to invade the lower reaches of river valleys including where you live. This drowning has produced large embayments such as Albemarle and Pamlico Sounds. New River (where you live) lies between this region and the Cape Fear uplift.

You might wish to look at the North Carolina geologic map for more detail:

(https://ncdenr.s3.amazonaws.com/s3fs-public/Energy%20Mineral%20and%20Land%20Resources/Geological%20Survey/1985_state_geologic_map_500000_scale_600dpi_rs.pdf)

To your east you have the Belgrade Formation, with oyster shells embedded in sand. To your north and west you have the River Bend Formation, also fossiliferous with limestone among other rocks. Both formations are listed as Tertiary in age (66 million to 2.6 million years ago). However, the shells you are seeing could conceivably be from the last several tens of millennia if I read your elevations and location correctly.

I hope this helps. You have some excellent geologists in your state, both at the state and university levels. It should be fairly easy to contact one - perhaps visit the closest university and ask to talk with a geologist there. 
~~~~~

Monday, August 22, 2016

Hunting Asbestos



This question opens the door to several issues: indirect detection when direct detection is not possible, and unanticipated down-sides (such as death) to some mineral exploration projects.

Q: Hello Sir,
Could you please tell which is the best method for locating asbestos, pyrrhotite and manganese? Whether airborne magnetic survey or ground magnetic survey?
Regards, Ahtisham ul-H.

A: Asbestos (an aggregate of six different but related silicate minerals) and manganese are not magnetic. Pyrrhotite (FeS) is sometimes weakly ferromagnetic if there are iron deficits in the ideal FeS lattice. However, these minerals are all usually associated with serpentinization, a hydration and metamorphic transformation of ultramafic (dark, iron and magnesium-rich) rock. Serpentinization usually has significant magnetite associated with it, and THIS is strongly magnetic. I've worked in ultramafic rocks where I have personally encountered 3-cm-thick veins of pure magnetite. It doesn’t take much more than a percent or two of this to make a rock really magnetic.

The usual method for mapping these sorts of deposits is ground magnetics and geochemistry, but keep in mind that you are only indirectly imaging the minerals you are interested in. Airborne magnetics are often used for regional surveying, to outline target areas for later follow-up with ground magnetics.

As an aside, please keep in mind that mining asbestos, or fabrication of asbestos products, is dangerous. My father died of mesothelioma-related lung cancer. In his 80's he was an avid bicyclist in San Francisco. The pipes in the basement ceiling of his apartment building, where he stored his bike, were insulated with blown-in asbestos. When he developed a persistent cough, a biopsy showed his lungs to be poisoned with asbestosis.