Meteorite Monday: Space Rocks, an encore edition

I’ve decided to take a quick break from my finals studies and put together a quick Meteorite Monday. This post is one that I wrote back in June 2010 when this blog was hosted on Tumblr. It was my first meteorite themed post and one that I transferred over when I made the leap to WordPress. It’s definitely not my best, but I think it’s interesting to see how my writing has evolved over the past year. While I wouldn’t say my writing is anything special, I do feel like it’s come a long way since then.

Enjoy the repost!

This summer I get to do my very first independent research project. I’ll be helping one of my geology professors finish classifying a meteorite with the use of an electron microprobe. This is my first time doing such a project and as such I have a lot to learn. But that’s the exciting part of doing science: the continual learning process. So, as such I figured it was time for me to learn about meteorites. Or meteors. Or meteoroids. Each name means something different. And according to my instructor, the classification has been changing lately. So, in my efforts to learn the basics about these ancient pieces of space debris, I will be posting what I’ve learned in my blog. To start, those confusing names.

It turns out the terms meteor, meteorite and meteoroide are not interchangeable. They seem to refer to the phases of change space debris goes through as it enters the earth’s atmosphere. This rock can come from the moon, comets, asteroids or even other rocky planets (most notably Alan Hills 84001 from Mars- that deserves a post of it’s own). Some of it can be left over material from the formation of the solar system, almost 4.5 billions years old. While their origins differ they pretty much go through the same process upon encountering the earth’s atmosphere.

The difference between the three names used to be simple. The flash of light produced by the entering debris was a meteor. Any chunks of rock that broke off were the meteoroids. And any piece that didn’t disintegrate in the earth’s atmosphere and made it’s way to the surface was a meteorite.

However, a paper recently published in Meteoritics & Planetary Science by Alan E. Rubin and Jeffrey N. Grossman proposed a complete overhaul of the definitions. They suggest that a meteoroid becomes a “10 micrometer to 1 meter sized natural object traveling through interplanetary space”. A meteorite is a natural object that is larger than 10 micrometers whose parent was any rocky celestial body. The meteorite had to travel under it’s own natural means with enough velocity to escape the gravitational pull of its parent body. It then has to hit something that is larger than itself, natural or artificial, and survive the impact. What is most interesting is that the meteorite doesn’t have to hit a foreign object. If it hits the surface of it’s parent body, it’s still considered a meteorite*.

So, those are the differences between the terms. I think in the next post about meteorites, I’ll cover the classification system. And as a side note, this is my first time writing about anything of this nature. In the very unlikely chance that someone from academia (or anyone at all) reads this, please be kind with criticism. I’ll happily accept feedback if done in a professional manner.

Mt. Hood ho!

The peak of Mt. Hood

Saturday reaffirmed why I chose to study geology. I went on a field trip to Mt. Hood with my geo 318 class in order learn how to identify glacial deposits and see the glaciers themselves. It was a fantastic trip. It was my first time to visit the dormant volcano in the three and a half years that I’ve lived here. As I had tweeted earlier, I truly wasn’t prepared for the sweeping views of the valley beneath us. Nor was I prepared for the decreased amount of oxygen available at 6000 ft above sea level. However, I survived the altitude sickness with nothing worse than a slight head ache. Not bad for my first time at that altitude outside of an airplane.

As was to be expected, the trip was a huge learning experience for me. When you’re taking a geology course, there is only so much the book can teach. The lectures and my text book gave me an idea of what a lateral and medial moraine looked like, but it wasn’t reinforced until I got onto the mountain and saw them first hand. The same can be said for glacial till, the polished boulders, the U-shaped valleys down below and the glaciers themselves. You can be an arm chair geologists all you want, but nothing makes sense nor coalesces into reality until you’ve seen it and touched it.

Glacial Till- My blog's namesake!

Undoubtedly, the glaciers had to be my favorite part of this whole trip. Since it was the end of Summer, their glory could only be seen in the immense moraines that were deposited on their gravity induced trip down the mountain. Come Winter, I may plan a trip back to Timberline to see the glaciers in their snow-bloated glory. After we hiked to about 8100 ft, some fellow students and I decided the quickest way back was to walk (or in some cases, slide) down the glacier. Was it the safest thing to do? Probably not. I’ll admit to having the occasional vision of a wall of snow, ice, and rock come roaring at me. But it was so much fun. There is nothing cooler than to say “I played on a glacier”.

As I reread my post and proofread it, I realize that this one sounds a bit romanticized.  Was it all fun and games? No. I ran out of water on the way down and got a nice little sunburn on my face, neck and arms. On some areas of the hike, we literally climbed our way up fine silt deposits. The stuff is easy to sink into and isn’t friendly to those trying to go over it. However, those were minor annoyances compared to what I learned and that reaffirmation of my love for geology. Chemists can keep their beakers and physicists their particle colliders. I’ll keep my rock hammer and stick to the great outdoors.

glacially polished boulder

I have more pictures from the trip. Once I get the album organized and put the captions in, I’ll add the link to this post.

Columbia River Gorge

I have a confession to make: until now, I’ve never fully appreciated the Columbia River Gorge. Don’t get me wrong,  I’ve always enjoyed hiking at Multnomah Falls and exploring Hood River (especially the breweries), but I never had much interest in the geology of the area. To be quite frank, and possibly uncultured, the sheer amount of basalt bored me. The beauty of the area wasn’t lost on me, but I always dismissed it and found southern and central Oregon to be more “worthy” pursuits. However, as a friend and I drove around the Gorge on Sunday, my attitude changed.

The Gorge is what geologists refer to as a Large Igneous Province . The current hypothesis states that during the Miocene, rifts opened in eastern Oregon and Washington, forming basalt floods. At that time they erupted around 170,000 cubic km of lava in 300 flows; 21 of which can be found the Gorge (courtesy of the CVO.) The first of these flows is called the Imnaha flow and started around 17.5 million years ago. It accounts for about 10% of the flows and is only visible in a few locations. The next flow is the Grande Ronde at about 15 million years ago. It makes up about 85% of the basalt flow and is generally visible throughout the Gorge in the lower levels of strata. It was then followed by the Wanapum basalt (~14.5 m.y.) and then the Saddle Mountain basalt (~13.5-6 m.y.) Throughout all this, the lower Columbia River slowly cut its way through the uplifting landscape, starting the formation of the Gorge. This is by no means a comprehensive list of the flows, but it gives a general idea of the amount of basalt that erupted over the course of millions of years. A drive through the Gorge helps to visualize the enormity of the basalt floods. It was this thought that made me reevaluate how I view the Gorge and the geological processes that shaped it.

It’s further humbling to think about the catastrophic floods that further shaped the Gorge. This sequence of flooding is called the Missoula Floods and they occurred in multiple inundation events towards the end of the last Ice Age. From Wikipedia:

After analysis and controversy, geologists now believe that there were 40 or more separate floods, although the exact source of the water is still being debated. The peak flow of the floods is estimated to be 40 to 60 cubic kilometers per hour (9.5 to 15 cubic miles per hour). The maximum flow speed approached 36 meters/second (130 km/h or 80 mph). Up to 1.9×1019 joules of potential energy were released by each flood (the equivalent of 4500 megatons of TNT). The cumulative effect of the floods was to excavate 210 cubic kilometers (50 cu mi) of loess, sediment and basalt from the channeled scablands of eastern Washington and to transport it downstream.

These floods deposited sediment into the Willamette Valley, making it the agricultural powerhouse that it is today.

As can be seen from this brief intro, the Columbia River Gorge didn’t have an easy birth. It formed by monstrous basalt flows that were steadily eaten away by the Columbia River and then dramatically purged by the Missoula Floods. This upheaval, while cataclysmic and terrible to witness is what has made for some of the most dramatic scenery in the Pacific Northwest.

Just for kicks pt. 2, or the Expanding Earth Hypothesis

Initially I wasn’t going to give anymore attention to this topic than my original post, “Just for kicks”. However, a fellow geoblogger, Cian Dawson, suggested that I put up some links refuting the Expanding Earth Hypothesis. In retrospect, that is what I should have done in the first place. To challenge an idea and not offer a valid counter argument can be rather disingenuous. So, here are a few links with information that refute the Expansion Hypothesis.  One was provided by Cian and the other three were provided by Brian Romans (pre-move to Wired) from his blog over at Clastic Detritus.

http://geology.about.com/od/platetectonics/a/Expanding-Earth-Animation.htm

http://clasticdetritus.com/2008/11/14/subduction-denialism-part-1-the-backstory/

http://clasticdetritus.com/2008/11/14/subduction-denialism-part-2-subduction-zones-trenches-and-accretionary-complexes/

http://clasticdetritus.com/2008/11/14/subduction-denialism-part-3-sedimentation-in-the-cascadia-subduction-zone/

A few of my own links:

Possible Subduction on Venus: (nothing conclusive, but still food for thought)

Flat Slab Subduction of the Coco’s Plate

The P-wave velocity structure of the mantle below the Iberian Peninsula: evidence for subducted lithosphere below southern Spain (abstract only)

A simple Google scholar search will yield more papers that have proven the existence of subduction, either directly or indirectly.   To those that would advocate the Expanding Earth Hypothesis I pose a few questions: How does your paradigm explain orogeny? How about the formation of the Himalayas and the Andes? Rifting doesn’t produce mountains on the same scale as subduction. Look no further than the Basin and Range Province for proof. How do you explain the existence of blueschist? It only forms in accretionary prisms which are found exclusively in subduction zones.

If the Expansion Hypothesis can explain such things, and do so with ample, verifiable evidence, then maybe it can be seen as a direct challenge to the Theory of Plate Tectonics. I personally doubt that will ever happen, but science isn’t based on belief, but on hard evidence. Prove it and we will believe.

Glacial Till

One of the features I love about WordPress is the ability to not only see the number of daily visitors to your site, but what led them to your site in the first place. This is shown as either a link from another website or it can come from search terms. As I was going through my statistics, I noticed someone had stumbled upon my blog while looking for information about glacial till formations. Unfortunately, not a single piece of information about glacial till can be found on my blog. My current interests don’t even include glaciers. However, I liked the concept of glacial till enough to snag it as my blog name. And let me explain why.

For the non-geologists, glacial till is one type of glacial sedimentary deposit. Much like rivers, glaciers wend their way through valleys (called fjords) eroding the landscape around them. Although they do this at a much slower rate than rivers the concept is still the same. The main difference is that glaciers can and will move any size of sediment around them. They act like giant conveyor belts that move sediment towards the front and deposit it at the toe of the glacier. This sediment is what geologists refer to as unsorted. Or in other words, it comes in all different sizes. So, one would expect to find boulders, gravel and smaller pieces of rock all within the same deposit.

How does this relate to my blog?

Well, at this point, I’m not interested in just one thing. I like to pick up everything around me and “deposit” it in my blog. Whether it’s geology, astronomy, general science, beer or even stuff I’m covering in school, it’s all fair game. It helps me to learn and retain information about things that interest and excite me. In time I’ll decide which area of geology to concentrate on, and if I’m still blogging, the content will become more refined as well. Until then I’ll continue to blog about the random pieces of science that catch my attention.

The Red Planet

Red Planet One of my favorite things to do is peruse the images returned by the Mars Hi-Rise Mission. I’m always blown away by the level of detail that the digital cameras reveal about the geological features of Mars. Seeing the dried out river beds, the wind sculpted terrain and the immense sand dunes is a stark reminder of the similarities possessed by both the Earth and Mars. With the Mars Hoax e-mail floating around, it’s nice to know that we can use actual science to get all the close-ups of Mars that we want without hoping that an internet rumor will turn out to be true.

My first blog post… kind of

So, as the title says, this is my first post… sort of. I did have a blog on another service (which I will not name) that I used sporadically. Part of it was the inefficiency of the former blog site and part of it was my not knowing what to write. I had intended to blog about my various interests (mostly general science), but I decided to focus on geology and space themed pictures and posts. Then I got involved in a small study on a meteorite at school and thought maybe I should devote my blog towards meteoritics. However, my lack of expertise on the subject made me feel inadequate to do so.

Where does that leave me? Well, as an undergrad geology student I will be taking a whole lot of science and math classes. Being the nerd that I am, I will undoubtedly find something that interests me and will want to blog about it. So, maybe that’s what I’ll focus on. Not on one topic in particular, but everything that will make me proficient in whatever area of geology I end up.

A meteorite by any other name…

I’m finally done with my meteorite analysis and write-up. What’s next? Blog it of course!

So, the whole point of my analysis was to determine the metamorphic grade of the meteorite. I was going to do this by using an electron microprobe to measure the calcium content of the pyroxene crystals. While the premise was simple, we had a rather complex problem. The meteorite was so shocked (probably between S4-S5) that the fracture of olivine crystals nearly mimicked the right angle cleavage of the pyroxenes. So, trying to tell the difference between the two was tricky. We had 43 points to scan and we hoped that about 15-20 would come back as pyroxenes. Here is where things get interesting.

Our meteorite should have had a composition that was roughly 60% olivine and 40% pyroxene. However, of the 43 points shot, only two came back as pyroxenes. And to top it off, the Ca content of the two was at just under one percent. This presents us with a rather vexing issue. What happened to all the pyroxene? Statistically we should have hit more than 2 crystals. Was it really bad luck on our part or are we dealing with a sample that has super-low pyroxene content? My two advisors that are assisting me with this project aren’t really sure. Either it’s an L6 chondrite or we have something really unique. And we won’t know until we get the thing on a Scanning Electron Microscope. So, until we can get a proper classification, the metamorphic analysis is on hold. I’m gonna keep my finger crossed that we have something more than an L6 on our hands.

Ontario Lacus

Ontario Lacus
No, you’re not looking at the imprint of Big Foots’ foot, but one of the latest shots of a lake on Titan. This beauty, Ontario Lacus, is the largest lake in the Southern hemisphere. I would explain more about the lake, but I’d be stealing words from the fine folks at JPL that put together the image. One thing I did notice that they didn’t mention was the meandering stream on the central west coast of the lake. It’s neat to see the fluvial process alive on Titan and acting the same way it does on earth. Unfortunately the link on Cassini’s site goes directly to the image and not the site itself, so here’s the description of the image: