Picture of the Week - Taconic Unconformity

The image below shows a rock outcrop on Route 23 west of Catskill, NY in the mid-Hudson Valley.

So what is this showing?  There are two distinct rock units here.  On the right are interlayered gray shales and sandstone and the beds are tilted such that they are almost vertical.  On the left are beds of an orange-brown rock called dolostone which are tilted about 45 degrees from horizontal.  There is a distinct contact between these two units running from the lower-left to the upper-right of this picture.

Shale is made primarily from quartz and various clay minerals (lithified mud).  Sandstone is made from quartz (SiO2).  Dolostone is basically limestone (calcium carbonate or CaCO3) with some magnesium tossed in -- (Ca,Mg)(CO3)2.  They're very different types of rocks.

Geologists call the unit on the right (the older one, since it's below the other), the Austin Glen Formation and they call the unit on the left (the younger one), the Rondout Formation.  It's actually very easy to distinguish them from each other in the field (they look more different in person than they do in the image).

This contact, where the Rondout Formation lies on top of the Austin Glen Formation and they both have different orientations is not just seen here. You can drive to other locations in the area to see this as well.  Geologists call this type of contact an angular unconformity.

Fossil evidence in the Austin Glen indicates it's from a period of time called the Middle Ordovician Period (let's say 465 Ma).  The Rondout Formation is from the Late Silurian Period (let's say 420 Ma).  That means that there's some 45 million years missing in that unconformity!  Missing rock strata indicates from that from around 465 Ma to 420 Ma, this area was undergoing a time of erosion - there were no sediments accumulating to later form rock layers.
 
A very basic principle in geology, first formulated in the mid-1600s by Nicolaus Steno in Italy, is that of original horizontality.  What this means is that sediments originally accumulate in horizontal layers which then lithify into horizontally-bedded sedimentary rocks.  If the layers are tilted, such as the one's above, then some force later tilted them.  Another of Steno's principles is superposition - the basic idea that in layered sedimentary rocks, the oldest layers will be at the bottom.  Pretty simple.
 
So what does the outcrop above tell us?  An entire sequence of events...
 
1.  Around 465 Ma, the Austin Glen Formation was laid down as marine muds and with periodic influxes of sands in horizontal beds in a deep basin (the fossils tell us this).  They gradually accumulated and were buried.  Over time they lithified into shales and sandstones.
 
2.  Sometime between 465 and 420 Ma, the Austin Glen rocks were tilted by some type of event.  Looking at numerous outcrops reveals that these layers were actually folded and cut through by faults due to horizontal shortening in a present-day east-west direction.
 
3.  Around 420 Ma, the Roundout Formation was deposited as horizontal sediments in a shallow, tidal-flat environment in a hot, arid climate.  Eventually these sediments were buried and lithified into beds of dolostone.  At this time, the angular unconformity existed between the Rondout and Austin Glen Formations but it too would have been horizontal.
 
4.  At some time younger than 420 Ma, Everything was folded and faulted yet again by another shortening event (again in a present-day east-west direction).
 
In other words, what this outcrop represents is two distinct tectonic events.  We know, from studying metamorphic and igneous rocks to the east, that these were huge mountain-building events.  To form each of the rock layers, tilt them twice, erode them flat, etc. will take very long spans of time - in this case tens of millions of years.  Some time later, I may discuss these but the post is getting long enough as it is.

One last thing I'll mention is that in 1788, a Scottish physician and amateur geologist named James Hutton saw an outcrop at Siccar Point on the coast of southwestern Scotland.  At Siccar Point, tilted strata of red sandstone dated around 345 Ma overlie almost vertical strata of graywacke (a type of sandstone) dated around 425 Ma (80 million years of missing time).  It's almost exactly analagous to the Taconic unconformity in Catskill.
 

Siccar Point from Wikipedia

 
Back in Hutton's day, they didn't know the ages of these rocks, but Hutton did recognize that such an outcrop showed an immense span of time.  To create such an outcrop through naturalistic processes would have taken far, far longer than the traditional 6,000 year Biblical age of the Earth.  It was the beginning of modern geology.
 
I could keep going for pages but I guess I'll stop here and pick this up another time.

Watch out for engineers

Interesting article in Slate titled Build-a-Bomber asking why so many terrorists have engineering degrees.  A study by two sociologists, Diego Gambetta and Steffen Hertog, has shown engineers were three to four times more likely to become violent Islamic terrorists than their peers in other disciplines.

I found this interesting because of a phenomenon called the Salem Hypothesis which holds that there is a correlation between being a leader in the young-Earth creationism movement and having an engineering degree.

From the Slate article:

"Gambetta and Hertog write about a particular mind-set among engineers that disdains ambiguity and compromise. They might be more passionate about bringing order to their society and see the rigid, religious law put forward in radical Islam as the best way of achieving those goals."

Substitute "conservative Christianity" for "radical Islam" and the above statement makes just as much sense.  I'm not trying to denigrate engineers, just noting that otherwise intelligent people who have an absolutist mindset about religion might be drawn more toward academic fields with little ambiguity.

Or this all may just be complete bullshit.

Jupiter & Galileo

Arriving home tonight around 5:30 pm, I saw a bright "star" low in the southwest sky.  Jupiter.  At magnitude -2, it was brighter than the brightest star - Sirius (which rose about an hour later).  I noticed recently that January 7 was the 400th anniversary of Galileo Galilei's observation of Jupiter's moons in 1609.  In Sidereus Nuncius - Starry Messenger, published in 1610, he wrote:

Galileo was the first to see moons orbiting Jupiter.  Why was this significant?   In 1543, a lifetime earlier, Nicolaus Copernicus proposed his heliocentric system - the model postulating that the planets all orbit the sun (in opposition to the classical geocentric model which held that everything orbited the earth).  Around 1605, Galileo's time, Johannes Kepler was modifying the Copernican model to ellipical orbits rather than circular ones.

Galileo's observation was a strong piece of evidence against a strict geocentric model of the solar system - here were objects orbiting something other than earth.  This use of the telescope by Galileo was the beginning of the end for the geocentric model.  Unfortunately, the Catholic church at the time held to the geocentric model as being the one in accord with the Bible.  And the Catholic Church in early 1600s Italy was not to be mocked.  By the way, Martin Luther, leader of the Protestant Reformation, also disbelieved the heliocentric model of Copernicus so it wasn't just the Catholics.

As an aside, there are lots of similarities here between 17th century geocentrists and modern-day evolution deniers. Both claim that a clear, literal reading of scripture supports their position.

Here's what you'd see if you looked at Jupiter's moons tonight (January 10) using a neat Javascript utility from Sky and Telescope.

The I, E, G, and C stand for Io, Europa, Ganymede, and Callisto - the four Galilean moons of Jupiter from closest to furthest from the planet. Tonight you would see Io on the left and Ganymede and Callisto on the right (Europa is in Jupiter's shadow).  In a couple of days (January 12), the view would be:

Io still on the right with Europa (now visible), Ganymede, and Callisto (must closer now) on the right.  Every night will show a different view.

Here's what it looks like through a telescope (from Wikimedia Commons).

A never-ending dance of light as the moons orbit Jupiter.  In 1676, Danish astronomy Ole Romer even calculated the speed of light from the movements of Jupiter's moons (maybe I'll write about that sometime - it's a cool story).  I also have my students in astronomy class do an exercise (Project CLEA) where they calculate the mass of Jupiter from the orbital periods of the moons.  It's amazing what you can learn by just observing (and a little thinking).  Too bad there are still people opposed to that (see the above comment about creationists).

Full-time vs. Adjunct Faculty

The New York Times had an article on Dec 30 about The Case of the Vanishing Full-Time Professor.  The article says that in 1960, 75% of college faculty were full-time and either tenured or tenure-track while today only 27% are.  The rest are graduate students, adjuncts (part-time faculty only teaching 1-3 classes each semester), or contingent faculty (typically on year-to-year contracts with no job security).

While the New York Times may have just noticed this, it's certainly not news to those of us working in academia (or many college students who pay attention to who's teaching them).  At the community college where I teach, we've had between 60-65 full-time faculty over the past few years (varies semester-to-semester based on retirements, new hires, and those out on sabbatical).  We also have around 150 or so adjunct instructors (which varies semester-to-semester as well).  Almost a three-to-one ratio of adjuncts to full-time.  I'm not sure what the numbers looks like if you look at the percentages of course sections taught by full-time vs. adjuncts since full-time faculty teach 5 course sections each semester (although several faculty have course reductions for being department chairs or coordinators) while adjuncts may teach 1, 2, or 3 sections (but no more than 3 for contractual reasons).  To figure this out for a specific semester, I'd have to print out all course sections for the semester and count it up (which I don't feel like doing today).

So why is this a big deal?  Well it's great for the bottom line of the college.  Adjunct faculty have no protections (you can decide whether or not to use them up to the first day of classes), they receive a lower rate of pay (and professors are paid poorly to begin with given their education), and they have no health or retirement benefits.  Cheap labor.

There's a downside for the college as well.  Full-time faculty do a lot more than simply teach.  They serve as department chairs and program coordinators.  They do periodic program and course evaluations required, in our case, by the State University of New York system in Albany.  They develop new programs and courses.  They serve on various committees which determine academic policy, hear student grievances, and plan the future direction of the college.  They advise and register students each semester.  They do research.  They engage in professional development.  They give talks and lectures outside of their classes.  Just a few examples.  That's why college faculty will laugh at you if you suggest they only work a couple of hours a day since those are the only times their classes meet.  It's not uncommon for me to work 50-60 hours a week.

Adjunct faculty generally do none of these things.  They typically come in, teach their course, and maybe hold one office hour a week.  Many adjuncts also teach at several colleges to try and make ends meet meaning they're spending much of their day commuting.  At our school, which is typical, adjuncts in each department get a large closet and a single computer shared with a dozen other people and it's called their "office."  They're often treated as 2nd class citizens - usually not intentionally, but simply because it's too hard to include them in the culture of the department when they're never around.

What's the downside for students?  As a department chair, I try my best to make sure that our adjuncts are good teachers.  We don't have to hire an adjunct each semester so if they're not good, why use them?  The real problems are harder to address.  The problems students have with adjunct instructors typically result from three things:

- Adjunct faculty can't interact with students as much as a full-time instructor can.  They come in, teach their class, and leave.  They have no advisees to develop relationships with during the student's time at school.  They are typically harder to reach (especially in person) when a student has a problem with the coursework.

- Adjunct faculty aren't as invested in the college as full-time faculty.  I want the college to do well and succeed.  I want to uphold academic standards.  I want a healthy enrollment.  I've invested years of my life here and I want to spend years more.  Adjunct faculty, often treated poorly by the college administration, don't have nearly the investment in the college.  If they're not teaching one class here, they'll pick it up elsewhere (or work at Wal-Mart for almost the same rate of pay).  If an adjunct faculty member feels a conflict between upholding the academic integrity of the course or making it easier to teach (and not catching flack for failing too many students) what do you think they'll do?

- Adjunct faculty often aren't as up-to-date in the subject matter as full-time faculty.  Many have other (even full-time) jobs out of academia.  They don't go to professional conferences or participate in professional development.  They don't often read journals in their field.  They don't often do research or write papers.  With each year, especially in areas like science, they fall further behind the cutting edge.  This matters, even in an introductory freshman-level course.

It's important to note that these are all generalizations.  I know adjuncts that I would hire as a full-time faculty member in a heartbeat and we'd be fortunate to have them.  I also know full-time faculty that I'd love to fire.  But I will say that, in general, it's better for students to attend a college with a higher percentage of full-time faculty.  That said, I don't think my institution is doing too badly.  If a student takes general physics at my community college, for example, they will be taught in a small class (max 30 students or so) and both lecture and lab will be taught by a full-time faculty member with a PhD in physics.  If they take the same course at a nearby state university, they will sit in a large lecture hall, never interacting with the professor, and be taught in lab by a graduate student (who may have no experience teaching and possibly poor English skills based on my undergraduate experience 25+ years ago).

I do fear, however, given the dire fiscal situation our idiot New York State government has gotten us into, that as full-time faculty retire over the next few years they will only be replaced by adjuncts.