greengabbro | March 21, 2008 So sand is just little weensy rocks, anyway. And this is a weensy volcano made of sand, in Peru. It’s about a meter (0.33% 0.9% of a football field thanks LL!) across.
Normally, layers of sand and silt underground bear the weight of whatever’s on top of them through a network of contacts between individual soil grains. During an earthquake, this network is disrupted. But the stuff on top is still there, bein' all heavy. Wacky hijinks ensue!
If the jiggling sand happens to be wet, all that overburden pressure is transferred to the water. Water, being incompressible, is not happy about being…
greengabbro | March 17, 2008Today, I am excited because I get to use the word "stomping" in some of my peer-reviewed serious science business. I like the word "stomping".
I also like the word "puddle" but I haven't managed to work that one in yet. Nor "titillating" (though I am citing a paper on "vibro-agitation", hur hur).
Anyway, since I am currently engaged in 24/7 thesis-related keyboard-smashing, perhaps you could give me some other challenge words to think about? The joy that I get from typing "impute" over and over and over is reaching a point of diminishing marginal utility.
greengabbro | March 14, 2008This is an outcrop of Bishop tuff, an ash deposit created 760,000 years ago when the Long Valley Caldera exploded - though “exploded” is, if anything, an understatement. The photo was taken 15 miles (25 of your Earth kilometers) away from the eruption; it contains no persons for scale, but the outcrop is about 10m high. Ash deposits from the same eruption are found all over Southern California and as far east as Nebraska.
Tuff is what happens when a pile of hot ash (”ash”) and fragments of exploded crap (”breccia”) consolidates and hardens under its own heat and weight. If the proportion of…
greengabbro | March 11, 2008 First, I'd like to say that these people have a point. There's a lotta white people on ScienceBlogs! More than in the science blogosphere generally? I don't know - pinning down the demographics of the blogosphere is tricky. More than in science generally? Razib has the numbers.
There are any number of places to go from here, but Alice has asked us all to share our ethnic stories, so that's where I'm going to go with this today. Perhaps I will carp on the defensive nature of people's response to observations of racial skew, or think of something intelligent to say about Janet's post, or fawn…
greengabbro | March 11, 2008It's one of those mornings where everything looks shiny and interesting - everything but the stuff I'm supposed to be working on. And wouldn't you know it, the Earth and Planetary Science Letters RSS feed just dumped a couple of issues on me. Surely I can at least blurb the interesting titles? It will be a prize for finishing my timed bouts of real work.
Sorry about the Elsevier paywalls. It couldn't be helped.
They poured honey into a sandbox - for Science! L. Mathieu and B. van Wyk de Vries, Dykes, cups, saucers and sills: Analogue experiments on magma intrusion into brittle rocks
The "…
greengabbro | March 9, 2008 First things first: Happy birthday, PZ Myers! (MOAR LOLPZ?)
Next things next: The Borg Overlords are working on a replacement for that "most active/most emailed" thing in the sidebar - one that gives more exposure to good posts from us wee little borgians, and less to gratuitous celebrity pix. The idea is to exploit engage a select portion of the readership to put favorite posts from across ScienceBlogs into a "best of" feed on del.icio.us.
Each of us in the Borg gets to pick two "Super Readers", who will be given access to a shared del.icio.us account for posting links. So I'm looking for…
greengabbro | March 7, 2008
Picture courtesy reader Martin. Or maybe Martin doesn't actually read this blog, and it's just Wren. Anyway, thanks, Wren and Martin!
Today's rock is a geopuzzle: What's up with these ridges? How did they get there, and what determines their size?
I don't actually know the answer, so this is the best hint you're going to get out of me.
greengabbro | March 6, 2008In light of the fact that Cal State is still committed to firing its nonviolent math teachers (the state attorney general has weighed in, supporting the dismissal, and Kearney-Brown is planning to pursue legal action), I thought I'd dredge up an old quip on the relationship between mathematical talents and a propensity towards violence.
In his talk, according to several participants, Summers also used as an example one of his daughters, who as a child was given two trucks in an effort at gender-neutral parenting. Yet she treated them almost like dolls, naming one of them "daddy truck," and…
greengabbro | March 5, 2008
Avalanches on Mars Caught on Camera! -- You can see the dust cloud. If that's not enough for you, the HiRISE team has just released 75 pages of droolworthy new Mars pix. Whoever is in charge of cropping these things has a good eye for composition. This is your official time-waster for the week.
NOVA Geoblog: Mineralogy of the atmosphere -- Will we eventually see an "urban varnish", like desert varnish but with more coal fumes?
Welcome two new geoblogs: Looking For Detachment and Geology Happens!
Wanted: Gray Literature on Women of Color in Science -- Please pass your hidden gems to Mia Ong…
greengabbro | March 4, 2008Until I saw Ed Brayton's post about a math teacher fired from Cal State East Bay for refusing to sign a loyalty oath, I had mostly forgotten that I might be technically guilty of perjury. Y'see, as a public employee of the state of California, I was required to sign that exact same oath:
I do solemnly swear (or affirm) that I will support and defend the Constitution of the United States and the Constitution of the State of California against all enemies, foreign and domestic; that I will bear true faith and allegiance to the Constitution of the United States and the Constitution of the State…
greengabbro | March 3, 2008Much of scientific communication consists of throwing up a graph and then explaining it. There are some basic procedures for doing this, many of which were probably ignored by the speaker at your most recent department seminar. Don't be that mumbledy jerkface who never explains the numbers on his or her unintelligible axes!
I suggest that you use the following graphic prompt to practice giving talks in the style of your adviser, department chair, or another charmingly be-mannerism'd colleague:
Reload the page to get a new one.
greengabbro | February 29, 2008 If you kick a dark pebble in the middle of the desert, you will sometimes find that it is light underneath. What this means is that you have disturbed a pebble that has been sitting there untouched for thousands of years. During that time, it accumulated a thin coating of windblown gunk - mainly clay dust, and manganese and iron oxides - known as desert varnish.
Desert varnish is not difficult to scratch through, and petroglyphic sgraffito is a popular artistic medium for native desert-dwellers and idiot tourists alike.
Desert varnish has a complex internal structure; there are thin…
greengabbro | February 29, 2008This post from Female Science Professor, about watching a colleague with ADD work, has been stuck in my head for the past couple of days:
So now he just lives with it and, although he hates his inability to focus, if he keeps going back to his original activity, even if he can't sustain that activity for more than a few minutes, he gets things done. In fact, he gets a lot done. He published 10 papers last year and wrote at least 2 successful grant proposals. And he is very well informed about the news and weather.
I don't have ADD, but I identify with many of the symptoms. I think this is a…
greengabbro | February 25, 2008 I didn't manage to get myself scraped off onto this month's Accretionary Wedge - oh, noes! While I am tragically subducted into the mantle, though, the rest of you can read about the many open questions currently puzzling the geoblogosphere.
Perhaps I can make it into the volcanic arc or something with a late entry about what's making me go "hmm" this afternoon. It's related to volcanoes, too: the behavior of glass beads suspended in a zinc iodide solution, spun between two cylinders.
The picture adorning this post is from an article by Völtz et al. in Physical Review E. They spun a…
greengabbro | February 22, 2008 This is a thin section from some Colorado shale. It's part of the Green River Formation, which is a series of rocks laid down about fifty million years ago when the West was wet. The shales come from a set of lakes that occupied part of what is now Colorado, Wyoming, and Utah.
If you look carefully - behind the white blotches, where the contrast is too blown out to say much but they might be grains of sand or bits of shell that fell into the lake where this was forming - you'll see that the shale was deposited in alternating layers of dark stuff and light stuff. The dark stuff is organic…
greengabbro | February 21, 2008Chad Orzel offers the following dorky poll:
If $3 billion were yours to spend on scientific research, how would you spend the money? ... For the sake of variety, let's restrict it to your own particular subfield, so, for example, how would I spend three billion dollars on physics?
If I had three billion dollars to throw at a single area of physics, I would obviously throw it at geophysics - but that kind of smart-alecky answer isn't going to cut it in the hypothetical world. No, the unspoken terms of the question demand that I spend $3,000,000,000 on a single project in geology. Moreover,…
greengabbro | February 20, 2008
The buzz in the geoblogosphere this week has been about an article in Nature Geoscience on the status of women in the academic earth sciences. I meant to review it here, but haven't had the oomph. Instead, you should join the discussion at All My Faults are Stress-Related, Ten Million Years of Solitude, and The Dynamic Earth. One point that hasn't been discussed much yet is that graduate school in the earth sciences is actually freakishly egalitarian - unlike other fields, we do not see large-scale gender fractionation between the master's and Ph.D. As a Ph.D. noncompleter I was tremendously…
greengabbro | February 19, 2008 I was trawling the USGS photo archive for upcoming Friday Rock Blog candidates when I came across this scanning electron micrograph of wheat. It's from a gargantuan volume published in 1981, full of initial reports about the eruption of Mt. St. Helens.
Why is there a picture of wheat in a book about a volcano?
It turns out people were curious about how quickly material from the ash would be incorporated into the soil nutrient supply, and particularly into crops. So a month after the eruption, USGS scientists sampled wheat and soil from fields that had been ashed on.
The answer? Wheat from…
greengabbro | February 18, 2008
I'm starting to see a light at the end of the tunnel that is grad school. I give it a 75% chance of being an oncoming train.
What this means for you, dear readers, is that in the coming weeks you'll be seeing a lot of bloggy self-plagiarism. I'll kick things off by posting a puzzle/meme I tried to start back in aught-one, which never caught on - probably because back then, we had to blog while navigating uphill both ways on monkey bars, and it's awfully hard to type with your toes.
Lo! Broil a new meme! Smile on cod, tilt silt, follow.
loft list:
T, doc, no E!
Ms. Wena
Orb
greengabbro | February 15, 2008Waterfall and Columnar Basalt © Joe Decker. Used with permission.
I finally found a piece from my nature photographer friend Joe Decker that would make a suitable subject for rock blogging. Y'see, the problem with fine art photographers is that they often forget to do things like add a rock hammer for scale. Also, they can have entire portfolio sections devoted to the Carrizo Plain without once showing an offset stream channel! It must be a very strange way to see the world.
Anyway, this image is of part of a lava flow in Iceland. As a new blanket of rock cools, it contracts. If it cools…