College Textbooks

Textbooks are expensive.  Students know this and professors know this.

At the institution where I teach, we use the same textbook for two different Earth science courses.  One course covers weather, climate, and oceanography and the other course covers geology.  Both are designed as State University of New York (SUNY) general education courses in natural science for non-science majors (in other words, students majoring in, for example, art, are required to take a natural science course as part of their liberal arts education and either of these courses work).

The text we use is a popular book that's been around a long time (13^th edition now) and, in my opinion, is well-written and comprehensive (full disclosure - Prentice Hall paid me to be a content reviewer of a recent edition of the text).

At our college bookstore (Folletts), this book sells for $163.25 new, $122.50 used, and there are rental options for new, used, and digital versions of this book (the digital rental is the cheapest at $76.75 for 180 days).

Amazon, on the other hand, charges $118.49 for a new edition of Earth Science and you can get free shipping.  The Kindle edition is $100.94 and doesn't expire in 180 days.  If you buy from 3rd parties through Amazon, you can get new versions as cheap as $88.00 plus $3.99 shipping and used versions for even less.  It definitely pays to get your textbook's ISBN from a professor early and order online.

I also place a version of the textbook on closed reserve in the library since we do have students who are simply too poor to purchase a textbook (the publishers and the bookstore hate this practice!).

Many students, of course, will opt to buy textbooks from somewhere other than the college bookstore (often from a student who took the course a previous semester) or simply opt to not purchase the text altogether (although, in my experience, students who don't read the text usually don't do as well in the course).  The college bookstore responds by not ordering a full complement of books for the course enrollment and then some students who wait until the last minute (usually for financial reasons - they can't buy a text until they get a financial aid check) can't even buy a text the first week of classes because it's too late to order online and the bookstore's sold out.

It's a mess.  At my institution this past fall we had chemistry students without a text three weeks into the semester due to the bookstore being unable to obtain more copies (chemistry students use their textbooks for problem solving assignments just like math students do - not having a text is a disaster!).

Speaking of chemistry, textbook costs are even worse for science majors - many lab courses in the sciences require both a text for lecture and a lab manual for lab (and lab manuals in geology run from $75-$100 and may not have used versions available because student write in lab manuals). In courses like chemistry, physics, and calculus, textbooks may be several hundred dollars in cost (although they may also be used for two or more semesters).

So why are textbooks so expensive anyway?  Geology textbook author Donald Prothero wrote an article on this very topic (Why are textbooks so expensive?).  It's complicated, publishers are the ones making the bulk of the profit, but the bottom line is that it's expensive to produce a book loaded with color illustrations and photos that needs a lot of peer review.

Many professors eschew textbooks altogether but I haven't done that yet.  Geology is such a broad subject, and so visual, that textbooks do help.  I simply can't cover all I need to cover is 42 hours of classes for a typical semester - students need to do that extra reading to flesh out the stuff I cover more superficially in lecture.  Many of them, of course, don't realize that, at least until the end of the semester when they see the final exam!

By the way, I'm always surpised when I see students selling back all their textbooks.  I still have my original physics text, chemistry text, calculus and differential equations texts, upper-level geology texts, etc.  While some topics do get out of date (introductory geology texts are different now than they were 30 years ago, but Newtonian mechanics hasn't changed).  I love textbooks and have tens of thousands of dollars worth in my office (of course, as professor, I get many for free now) and refer to them surprisingly often!

Apocalypse, what apocalypse?

 

Chickadee

Just a picture of a black-capped chickadee (Poecile atricapillus) at Spring Farm on the Mohonk Preserve.  This is from my hike a couple of days ago on Christmas Eve day.

Judging by birds at my winter feeder, chickadee populations have declined in recent years (although this year we seem to be seeing a few more which is hopeful).  I like the little guys and love hearing their calls.

The Gift of Homeschooling

As regular readers of this blog know, my wife and I homeschool our two tween-age children.  I'm a community college professor and my wife stays home with the kids.

It's a sacrifice living on one salary (most people are surprised when they learn how little community college professors are paid - around here, it's significantly less than the local high school teachers and everyone thinks they're underpaid).  The benefits are good but the administration is always trying to chip away at them and I've been 2.5 years without a contract.  Anyway, this time of year is always rough with higher electric bills, fuel bills (both of which I sent out today), and the holidays with all that entails in terms of groceries for dinners and gifts for family.

We live in a very modest modular home, I'm currently driving a 1998 Saturn with 190,000 miles on it, and we have old, mismatched furniture I'm somewhat ashamed of when friends and family come over to visit.  My wife and I rarely buy new clothes and we carry pay-as-you-go TracFones.

So, with all of the financial struggles, why do we homeschool?  We could send the kids out each morning to the school bus, my college-educated wife could get a full-time job, and we could easily bump our salary up to over $100,000/year.  Things would be easier financially.  But, as those of you who homeschool know, our lives would be dramatically different.

As a professor, I have a flexible schedule (it doesn't mean, what some people think, that I only work a few hours a day - flexible means I can do my course prep and/or grading at home at night rather than in the office during the day).  I can leave work in the afternoon and shoot off model rockets with a bunch of home-schooled kids and their parents.  We can go with another homeschooling father and learn about tree identification.  We can take month-long driving trips across country to see national parks.  We can go caving and learn about karst and groundwater in the middle of the day. We can have other kids over some afternoon to learn about dinosaur trackways.  We can teach them Greek, just for the fun of it, even though it's not part of the NY State curriculum. [Screw the NYS curriculum - as a community college professor I see the kids who come straight out of high school and they're illiterate and innumerate - not ghetto kids, by the way, these are regular, middle-class kids from OK families]

Yes, you can do all of those things and have public-schooled kids, but not usually as a family.  There's always some one's work or school schedule to worry about.  If something comes up, we can suspend formal schooling for a while without problem.  We continue schooling throughout the summer.  The kids move through stuff at their own pace (not a pace determined by a teacher) and they don't advance in subjects like math until they have mastery.  We don't separate learning from other activities - all of life is educational and learning.  They don't think of learning or reading as something for "nerds."  We don't watch broadcast TV (we don't have it) but we all read books every single day.  I would match my kid's knowledge and educational level against any public school kid any day of the year (except in popular culture - without the TV they wouldn't recognize some of the popular "celebrities").

My kids likely won't remember our old brown couch with holes in it (the one I'm sitting on now).  They will, I hope, remember rocket day and hiking with dad, and camping in Yellowstone.  They will remember a mom who was with them at home as they grew into young adults and the freedom and encouragement to pursue their own interests wherever it led them.

All I want for Christmas is for it to continue in the future as well as it has to date.  In another 10 years, we'll see how it all turned out!

The Catskills

Went for a hike today (likely the last for a while if the forecast for snow holds).  I took a series of nine photos of the distant Catskills from Spring Farm at the Mohonk Preserve in the Shawangunks (41° 47.780' N, 074° 07.531' W).  The photos were then stitched together with Hugin, a free program that allows you to easily create panoramas.

The view is looking to the northwest over the Rondout Valley.  I then did my best to label a number of the peaks (hopefully correctly).  Click here for the zoomable huge version.

By the way, to a geologist, the Catskills are not true mountains.  They're composed entirely of flat-lying sedimentary rocks shed off an ancient mountain belt to the east (the Devonian Period Acadian Mountains).  They're actually a dissected plateau.  Still pretty!

What people do when they're bored...

 

 

Yes, it's a dissected hot dog.  I have a weird family.

Happy Solstice!

 

 

Today, December 21, at 6:12 am EST, was the winter solstice. The time in the Earth's orbit where the Northern Hemisphere has its maximum tilt away from the Sun and the Sun is at its lowest in the sky. It's also the first official day of winter.

 

Why is it not the coldest day of the year?  It is, after all, the day with the least amount of insolation (incoming solar radiation).  Here in the Hudson Valley, it's currently raining and almost 50° F outside.  It's because temperatue lags behind insolation.  The winter solstice is not the coldest part of the year because it takes time for the Earth to cool as we move through the winter season and it's coldest in late January/early February (and, similarly, not hottest at the June summer solstice but in late July/early August).

It is the shortest day of the year in the Northern Hemisphere.  Here in the mid-Hudson Valley, we only have 9 hours and 39 minutes of time between sunrise and sunset.  By New Year's Eve, we'll have 20 minutes more of daylight as the sun rises 8 minutes earlier and sets 12 minutes later.

You can easily see why virtually all ancient cultures noted the solstices and marked them by celebrations.  Many believe that the western church placed Christmas at this time of year to replace the traditional midwinter pagan celebrations at that time.

I try to make it a point to be in tune with the sky.  To notice the shortening and lengthening days, the movement of the Sun throughout the year, the changes in the constellations, and the phases of the Moon.  The paper calendar we base our lives on is completely artificial but it's based, ultimately, on something real - the movements of the Earth and Moon in their orbits around a star.  Something we can see and experience if we just look up and pay attention to the natural world around us.

Mayan Calendars

The Maya are famous for their calendar system which, unfortunately, has been seized upon by many people who are peddling nonsense about this calendar predicting the end of the world on the winter solstice (December 21) of 2012. Since that's tomorrow, let’s tale a look at this a bit more closely.

The Maya actually had three different versions of calendars - the Tzolk’in, the Haab', and the Calendar Round.

The Tzolk’in

The first calendar was 260 days long and called the Tzolk’in. It was believed to be a religious calendar but no one knows for sure. Why 260 days? Many researchers believe that it was established in Copan – a major early Mayan site in Honduras near the Guatemalan border. It’s the time between passages of the Sun through the zenith (the point directly overhead at 90° of altitude).

The Sun is never directly overhead here in New York. It’s directly overhead exactly once if you live on the Tropic of Cancer (23.5° N latitude) on the summer solstice (because of the 23.5° tilt of the Earth’s axis). It’s directly overhead twice a year at latitudes between 0° (the equator) and 23.5° (the Tropic of Cancer). According to Wikipedia, Copan is located at 14° 50’ 24” N latitude and 089° 08’ 24” W longitude. The Sun passed through the zenith around noon on April 30 and again on August 13 in the year 426 CE (the date of the founding of Copan). The span of time from August 13 to April 30 is exactly 260 days.

While not all researchers agree with this explanation, it does work out nicely. Some have also argued that 260 days is the average number of days between the first missed menstrual period and birth (although this obviously isn’t very exact). Others have argued that it’s the number of days between planting and harvesting in agriculture (very contrived, in my opinion, since it depends on what you plant, weather, etc.).

The Tzolk’in is subdivided into 20 names of days (reflecting the vigesimal, or base-20, system of the Maya) with each day assigned a number from 1-13. This gives a total of (20x13) = 260 days. Each of the 20 names is also associated with a glyph. For example, the ninth named day is Muluk (“water”) and the glyph is shown at upper right. The fourteenth named day is Ix (“jaguar”) and the glyph is shown at lower right. Below is a table of all 20  day names and their meanings.
 

 
The way the Maya assigned names and numbers to days in the Tzolk’in calendar is complicated. It starts with Imix-1, Ik’-2, Ak’bal-3, K’an-4, … Eb-12, Ben-13, Ix-1, Men-2, …Ahaw-7, Imix-8, … Manik’-13, Lamat-1, Muluk-2, etc. In this way, every unique combination is hit.

The Haab'

The second calendar is called the Haab' and it was 365 days in length – the approximate length of the tropical year. The Haab' was a civil calendar and consisted of 18 months of 20 days each (there’s that 20 again!) which gives (18x20) = 360 days. An extra 5 days (called the Weyeb) were tacked on and these were considered unlucky days (other cultures have had this exact same system) where the veil between the mortal realm and the underworld disappeared.

 

One problem with the Haab' is that it ignored the extra ¼ day in the tropical year so the solstices and equinoxes occurred on different dates by a ¼ day each year (the ancient Egyptian calendar and the modern Muslim calendar do the same thing). Even though this calendar did not mark the true length of the tropical year, the Maya did know its length which they determined to be 365.2420 days (a value that compares well with modern knowledge).

Dates were specified as day (0-19) and then the month name. The year began with 0-Pop. Full dates in the Haab’ calendar were given as k’in (the day), uinal (the month name consisting of 20 kin), tun (the 365 day year consisting of 18 uinal), the k’atun (a cycle of 20 tun), and the b’ak’tun (a cycle consisting of 20 k’atun). There were then 13 b’ak’tun in a cycle before it begins all over again. This is referred to as the Long Count.

 

Long Count dates are written by modern scholars in the following format:

 

     e.d.c.b.a

 

Where:

 

     a = A cycle from 0-19 k’in (equivalent to our 20 days in a month) – 20 days

     b = A cycle from 0-17 uinal (equivalent to 18 months in a year) – 360 days
     c = A cycle from 0-19 tun (equivalent to a cycle of 20 years) – 7,200 days
     d = A cycle from 0-19 k’atun (equivalent to a cycle of 20 tun) – 144,000 days
     e = A cycle from 1-13 b’ak’tun (equivalent to a cycle of 13 k’atun) – 1,872,000 days

So a long count date ranges from 0.0.0.0.0 to 13.0.0.0.0. The date of 0.0.0.0.0 supposedly dates to the Mayan creation on August 13, 3114 BCE (on our modern Gregorian calendar). Note that August 13 is the date the Sun passes through the zenith in Copan as discussed above. Since a complete cycle of 13 b'ak'tun is 1,872,000 days, the cycle ends in (1,872,000 / 365.24219) = 5,125.37 years. This corresponds to December 23 (not the 21st), 2012 CE (cue spooky music).

Archaeologists have worked very hard to find some data points where we can convert the Maya Long Count dates to Gregorian calendar dates. They’ve been able to do this with Mayan records of eclipses (we can calculate when they occurred with reference to our calendar). There are no reputable Mayan scholars or astronomers who believe anything untoward is going to happen at the end of the Long Count (other than the rolling over and start of a new Long Count cycle).

One interesting thing about the Long Count is that 5 Long Count cycles of 5,125 years is 25,625 days, the approximate length of the precessional cycle – this is the cycle of the wobble of the Earth and shifting of the Pole Star over time. Many believe the Maya knew of this cycle (as did the ancient Babylonians).

 

The Calendar Round

 

The Maya also had a third cycle, called the Calendar Round, which is the multiple of the 260-day Tzolk’in and the 365 day Haab’. It was therefore (260x360) = 18,980 days or 52 Haab’ years. The end of the Calendar Round was a time of anxiety as they waited to see if the gods would grant them another cycle (it would only occur once in anyone’s life). This was also a time when many of their temples were renovated.

 

End of the World?

 

So will the world end when the Long Count resets to zero?  NO!  Plain and simple.  I'll post "I told you so!" on the 24th (just in case the 23rd is the more accurate date).  What gets lost in all of this is how freaking smart the ancient Maya were in figuring out these calendar systems and matching them to astronomical observations (all before calculators and such).  Pretty cool.

So anyway, I'll be waiting out the apolcalypse by having a few beers on Friday (or maybe I'll live it up at the end with some single malt scotch) and celebrating the solstice and the start of lengthening days (even though winter begins).

Rivers on Titan

Back in late September, the Cassini spacecraft which is orbiting Saturn's moon Titan, took an image near the north pole of that moon which is just incredible.  It's a 400 km (240 mi) long river.  Below is a small part of the image, cropped and rotated:

To get the full hi-resolution image from NASA-JPL, go here.  This is a classic dendritic (branching) drainage system as you'd see anywhere on Earth.  The river runs into a sea, called Kraken Mare, just off to the left in the image above.

There is a major difference between this river and rivers on Earth, however.  The temperature on Titan averages around -180° C (-290° F) and at that temperature, water is solid as rock.  Methane (CH₄) and ethane (C₂H₆), however, can exist as liquids, solids, and gases at pressure (1.4 atm) and temperature conditions found on Titan.  Below is one model of how this might work:

Strange new worlds.  There's some very cool atmospheric chemistry going on here.

Krampus

How could I have gone my whole life without hearing about Krampus?  Just a few weeks ago, I learned of this figure from Germanic folklore (and I'm half German).

Krampus is a demonic-looking hairy creature with cloven hooves, goat-like horns, and a long pointed tongue.  He accompanies Saint Nicholas and while St Nick rewards the good children with toys, Krampus carries off the bad children in a basket.  Different stories have him either drowning, eating, or carrying off those bad kids to Hell.

I tried to tell my kids to be good or Krampus will carry them off but they just laughed at me.  I should have started when they were younger.  I do like Krampus, though, probably because I'm so Scrooge-like about Christmas.

Apparently, the Krampus mythology dates back to pre-Christian times and while the church has tried to temper celebrations of a devil-like figure, some people still keep the idea alive.  See Krampus.com for some neat information and images.

Saw The Hobbit

STOP READING IF YOU DON'T WANT SPOILERS!

Took the kids to see The Hobbit yesterday.  As a nerd, I was looking forward to it myself having read the book several times since I was younger.  Mostly enjoyed it with a few caveats...

1. Did not see the 3D or 48 frames per second version so can't comment on them.  Just the regular movie.
2. Visually stunning non-the-less as you'd expect if you saw the LOTR.  I so much want to go to New Zealand some day!
3. I liked the prelude in the Shire with Frodo.  Linked together The Hobbit with the LOTR quite well even though it wasn't in the book.
4. I had trouble with the dwarfs.  Not the way I pictured them in my mind's eye - especially Thorin who was clearly eye-candy in this movie.  Balin was good, the others mostly forgettable or just silly.
5. I did like the backstory of Thorin added by Jackson even though it wasn't entirely canonical with the books.
6. Didn't mind the scenes with Elrond, Saruman, and Galadriel even though they're non-canonical as well.  It came across as plausible and again linked with the LOTR.
7. The encounter with the trolls was changed, not really for the better in my opinion.
8. I really didn't like the goblin city stuff.  Too much like Indiana Jones and numerous other Hollywood special effect extravaganzas, too long, and completely unbelievable (I realize that using the term unbelievable for a movie like this is a stretch but I can believe in Middle Earth!).  The goblin king was too cartoonish for my taste.
9. Didn't like Radagast and his bunny sled either.  Reminded me of Jar-Jar or the Ewoks in Star Wars - something the director thought was cutesy or whimsical to add but came across as stupid (at least to me).
10. Did like the riddle scene with Gollum.  Well done.

I didn't find it too long (other than I wish there was a pause button for movies over 2 hours so I can go pee without missing anything!).

Stories rocks tell

I went for a hike at the Mohonk Preserve yesterday since I had no final exams scheduled (it was the day the English department did all of their group finals).  One of my courses, Physical Geology had finished the day before and was already graded so it was nice to be able to take advantage of the relatively nice day here in the Hudson Valley (mid-40s and sunny - not bad for mid-December).

For those familiar with the Preserve, I hiked up from Clove Chapel to Copes Lookout and back.  Not sure of the mileage, but it's a 1,000 foot or so elevation gain which makes for a little exercise.  On the way, I was thinking how one of the goals of my geology courses is to teach students how to see (that's why field trips are so important in geology).

This for example:

To most people, it's just a rock sitting in the woods.  Kids usually like rocks like this because they're fun to climb up and sit on the top.  To a geologist, however, it's a glacial erratic.  An out-of-place rock.  How did this boulder come to be sitting atop the bedrock out here in the woods?  No one placed it here.  Geologists know that this rock was once entrained within glacial ice during the last ice age and dumped here when the ice melted.

While hiking up the bedrock ledges, some people might notice that the rock, in places, is smooth and polished making for slippery footing when wet or icy.

Geologists, however, see glacial polishing and striations.  The rock was polished and scratched, not by ice, but by the rocks and sediment picked up and trapped within the glacial ice as it relentlessly slid southward during the great Pleistocene ice age.

Similarly, these little fractures would probably go unnoticed by most people walking past them on the trail.

But a geologist like me would utter "chatter marks" and get out their camera to snap a picture envisioning, in their mind's eye, a larger rock at the bottom of the glaciers skipping and chipping along the bedrock as the ice rode over it so many years ago.

When you take a geology course, those gray rocks start catching your eyes and telling stories.

Martian Conglomerate

Earlier this fall, NASA announced that the Curiosity rover found an interesting rock outcrop on Mars.  Here it is poking up out of the red Martian sands...

 

 

The outcrop, nicknamed Hottah, shows some interesting features when examined close-up.

 

 

It's a conglomerate with rounded pebbles weathering out.  A little closer...

 

 

That circled pebble is a bit over a centimeter across.  This outcrop represents a sedimentary rock known as conglomerate - pebbles and sand cemented together by silica (typically).  What do geologists think when they see rounded pebble conglomerates like this?  Running water.  Streams.  These pebbles are too large to have been transported by winds and the rounding indicates water transport (look at the sediments in the bottom of any stream to see similar pebbles).

 

Here on Earth, these types of rocks are very common.

 

 

Above is an example of a local conglomerate from the Shawangunk Ridge on the Mohonk Preserve.  It formed from braided streams flowing off the ancient Taconic Mountains to the east over 420 million years ago.

 

 



Above is a slightly different example of a local conglomerate.   This is from the Catskills near North Lake and the results of rivers flowing off the ancient Acadian Mountains a bit less than 400 million years ago.

 

Not much different from the stuff we now see on Mars!

 

So, back to Mars.  Why a river deposit here?  Because we're near the outlet of a 30 meter deep canyon (Peace Vallis) that cuts through Gale Crater.  At the mouth of the canyon is a feature called an alluvial fan.  Alluvial fans form when water flows fast through a canyon and then comes out onto a valley floor.  As the water spreads out, it slows down.  As it slows down, it drops sediment.  A fan-shaped wedge of sediment then develops.  Here's an alluvial fan on Earth (for scale, that's a road cutting across it).

 

 

Here's the alluvial fan on Mars.  The oval was the targeted landing area for the rover and the plus sign is where it actually touched down.

 

The Hottah outcrop represents a stream channel coming off of that alluvial fan further confirming what we already know.  Liquid water once flowed over the surface of Mars!

December 13-14 meteor shower

Tonight, Thursday December 13 into the early hours of Friday, December 14 will be the annual Geminids meteor shower.  Meteor showers are named from the constellation they appear to radiate from, in this case Gemini which rises here in the Hudson Valley around 7 pm EST (look to the left of the more-recognizable constellation Orion).

Meteor showers are the result of the Earth moving through a field of debris typically left by a comet at some point in the past.  The Geminids are an exception, however, since the debris is from an asteroid named 3200 Phaethon.  The fields of debris are scattered around the path of the Earth's orbit around the Sun and therefore certain meteor showers periodically occur each year.

As a general rule, meteor showers are best after midnight.  In the diagram below, position A is just after sunset on the trailing side of the Earth while position B is before sunrise (after midnight) on the leading side of the Earth in its orbit around the Sun. At position B, we're plowing right into the debris field left by a comet and the meteor shower will be at its best. Continuing on in that direction off into space is the constellation of Gemini - the radiant of the meteor shower.

Below is the view you'll see high in the southern sky at midnight showing Gemini, Orion, Taurus, and a bright Jupiter (Betelgeuse and Aldebaran are distinctive too, being reddish stars).

As mentioned above, this meteor shower is caused by debris from asteroid 3200 Phaethon which is unusual.  This asteroid has a highly elliptical orbit, inclined 22 from the plane of the ecliptic, which brings it from out beyond Mars (2.4 A.U.) to inside the orbit of Mercury (0.14 A.U.).  This makes it an Apollo asteroid - one that crosses the Earth's orbit.  It's close approach to the Sun is why it was named Phaëton after the son of the Sun god Helios in Greek mythology.

JPL-NASA Small Body Database Browser

While most Apollo asteroids don't leave debris behind to form meteor showers, 3200 Phaethon is apparently composed of ice as well as rock (making it similar to a comet, but more rocky) and as it approaches the Sun, some of the ice is sublimated away and it sheds material.

Tonight's meteor shower should be pretty good for the Hudson Valley because we should be mostly clear (take it from me, having taught Observational Astronomy this fall, that's relatively rare!).  It's also a new moon which is good because moonlight washes out the fainter meteors.  The forecast is for the Geminids to have 100+ meteors per hour at its peak which is a couple every minute.  Given how cold it will be tonight (mid-twenties), that's good because it will be hard to stay out too long waiting!

Comment & a couple of mine pics

So, I haven't been posting much at all this fall as I've been mega-busy with my job as professor and department chair.  I also taught a bunch of extra courses above and beyond my required course load (I needed the money) so many non-essential things (like this blog) took a backseat.  Things are calming down now as we enter final exams so I hope to begin posting more.

One of the projects I have to get to is my external hard drive which has something like 100 GB of pictures that are in complete disarray and need to be sorted.  It's starting to get annoying because I'll be lecturing on, for example, geysers in Yellowstone and I know I have pictures I've taken from several trips there in the past but can't immediately put my finger on the pictures.  It's a heck of a lot of work to sort images.  They're in folders so my plan over break is to just sort a few folders a week, a little at a time, so that the scary, unmanagable-looking job is broken down into smaller bite-sized chunks that are doable.

As I go through the images, I'm sure I'll find many I can post to comment on in the blog.  Here are a couple to start things off...

This is an image of a Rosendale cement mine from 1920 taken by Harold Wanless (1898–1970) - then a Princeton University and later professor for 44 years at the University of Illinois (which I also attended for a time).  Around this time, the Princeton geology department led yearly trips up to the Rosendale, NY area to study the geology here (I live in the town of Rosendale myself).  There's a lot more I can write about this, but it will have to wait for another time.

The mines are still here.  This is a modern shot of a Rosendale cement mine, taken by me a couple of years ago.  The rock unit missing (but still preserved in the pillars) is the Rosendale dolostone member of the Rondout Formation.  Mined, baked in a kiln, and then crushed, it made an excellent natural cement that was world-famous at the time.  The roof of the mine is the Glasco limestone member of the Rondout Formation, which did not make a good natural cement so was left behind.

Note the tilt of this mine as it dips downward to the right?  That's because these Upper Silurian Period (~420 million-year-old) rocks were folded (and faulted) long after they were deposited on an ancient seafloor as witnessed by the coral fossils and calcarous sponges (stromatoporoids) in the Glasco.

 

Above is a picture from Wanless.

 

 

And this is my own.  The 100-year span of time between these images seems like a long time, but multiply that 100 years by about 4,000,000 to get back to the time these guys were sitting on a subtropical seafloor here in what was to become the Hudson Valley.  I still think that's pretty cool!

Saturday, December 8 Talk

Next Saturday, December 8, I'll be giving a talk at the annual meeting of the Century House Historical Society at the Rosendale Community Center (directions).  It starts at 1:00 pm, it's free, and all are welcome.

Here's the description...

ROSENDALE: 400 MILLION YEARS OF HISTORY

While many people know that the Rosendale area was once famous for its natural cement, fewer realize that this geologic resource was due to a unique set of environmental conditions which existed a little over 400 million years ago.

Join SUNY Ulster geology professor Steven Schimmrich as he discusses how we know that our area was once dominated by Himalayan-sized mountains, erupting chains of volcanic islands, and shallow subtropical seas and how these conditions formed the sedimentary rocks and structures we see in our backyards today.