Fresh daffodil pollen grains seen under 1000x magnification.
For the record: Daffodil flowers have both male and female parts, which make them good subjects for dissection. And, it’s pretty easy to collect daffodil pollen samples to look at under the microscope. 1000 times magnification seems necessary to be able to make out structures.
Since prehistoric pollen, collected from places like the bottom of lakes, are one of the easiest ways of finding past climates, a study of more recent samples might make for a good student research project in biology or environmental science. They’d need to design the study so they could avoid having to use nasty acids (hydrochloric or hydrofluoric) to concentrate the pollen grains, but that should be possible. Perhaps an ongoing survey using pollen traps, akin to the European Pollen Monitoring Program.
Clays and Silts (mud) deposited when the river floods.
Bedrock. Mostly limestone:
Can be found outcropping on the hills.
Mississippian Limestones (USGS ref.) (330-360 million years old.): found on some of the hilltops.
Ordovician Dolomites and Limestones (USGS ref.) (435-500 million years old)
The geology of St. Albans consists of young floodplain sediments (yellow), and old limestone bedrock (blue). Image adapted from the USGS.
Geologic History
The continents form
To reconstruct the geologic history, we can start a bit deeper, with the fact that we’re sitting in the middle of a continent, which means that if you drill deep enough you’ll get to some of the original, granitic rocks that formed just after the crust of the Earth cooled — about four and a half billion years ago.
The froth that floats on top of the boiling jam is a bit like the continental crust.
The continental crust is a bit like the froth that forms on moving water (or the top of boiling jam), and just like froth it tends not to want to sink. So there’s some pretty old continental crust beneath the continents.
However, also just like froth on water, the continental crust is pushed around on the surface of the Earth. This is called continental drift (which is part of the theory of plate tectonics). Sometimes, the continental crust can split apart, making space for seas and oceans between the drifting continents, and causing parts of the continent to subside beneath the oceans.
At other times, such as when two continents collide, they can push each other up to mountains out of areas that were once seas.
And that’s how we ended up with limestone rocks in the middle of Missouri.
Forming Limestone Rocks (Ordovician)
Five hundred million years ago (500,000,000 years ago) the continents were in different places, and Missouri was under a shallow part of the Iapetus Ocean.
The location of Missouri 458 million years ago. Image from: "Plate tectonic maps and Continental drift animations by C. R. Scotese, PALEOMAP Project (www.scotese.com)"
Many of the micro-organisms that lived in that ocean made shells out of calcium carbonate.
100 million year old, calcium carbonate shell (from Coon Creek).
When you accumulate billions of these shells over the course of millions of years, and then bury them, compress them, and even heat them up a bit, you’ll end up with a rock made of calcium carbonate. We call that type of rock: limestone.
Limestone outcrop on St. Albans Road (Ordovician).
Emerging from the Oceans: The Formation of Pangea.
The Mississippian limestone rocks formed in the same way, but about 360 million years ago. Why is there a gap between the Ordovician rocks (450 million years ago) and the Mississippian ones? Good question. You should look it up (I haven’t). There may have been rocks formed between the two times but they may have been eroded away.
I can make a good guess as to why there are no limestone rocks younger than about 300 million years old, however. At that time the continents, which had been slowly sidling toward each other, finally collided to form a super-continent called Pangea.
What would become North America (called Laurentia), ran into the combined South America/Africa continent (called Gondwana) pushing up the region, and creating the Ozarks and Appalachian Mountains.
Laurentia collides with Gondwana. Image from "Plate tectonic maps and Continental drift animations by C. R. Scotese, PALEOMAP Project (www.scotese.com)"
And that’s the story the geology can tell.
References
The USGS has good, detailed, interactive maps of the geology of the states in the US.
A nice geologic map of St. Louis County can be found here.
A geologic time scale from the USGS. The geologic time scale. From the USGS via Wikipedia.
A discussion of the physics of flight, interspersed with birds of prey swooping just centimeters from the tops of your head, made for a captivating presentation on avian aerodynamics by the people at the World Bird Sanctuary that’s just west of St. Louis.
Lift
The presentation started with the forces involved in flight (thrust, lift, drag and gravity). In particular, they focused on lift, talking about the shape of the wings and how airfoils work: the air moves faster over the top of the wind, reducing the air pressure at the top, generating lift.
The shape of a bird's wing, and its angle to the horizontal, generates lift. Image adapted from Wikipedia User:Kraaiennest.
Then we had a demonstration of wings in flight.
Terror from the air.
We met a kestrel, one of the fastest birds, and one of the few birds of prey that can hover.
Kestrel.
Next was a barn owl. They’re getting pretty rare in the mid-continent because we’re losing all the barns.
Barn owl.
Interestingly, barn owls’ excellent night vision comes from very good optics of their eyes, but does not extend into the infrared wavelenghts.
Barn owl in flight.
Finally, we met a vulture, and learned: why they have no feathers on their heads (internal organs, like hearts and livers, are tasty); about their ability to projectile vomit (for defense); and their use of thermal convection for flying.
The ground warms when it absorbs sunlight (e.g. parking lots in summer) and in turn warm the air near the ground. Hot air rises, creating a convection current, or thermal, that the vultures use to gain height.
The Sanctuary does a great presentation, that really worth the visit.
Astronaut Don Pettit makes water droplets orbit a knitting needle. Instead of gravity, the attractive force that holds the water droplets in orbit is generated by the static electric charge on the knitting needle and on the water droplet. This works because gravity and electromagnetic forces follow similar rules (inverse square laws).
My students always have the right to expect a reasonable answer from me to their questions. Even the hard ones that don’t have to do with the subject at hand: things like, “why do I have to learn this, I’m not going to be an engineer?” It’s part of authoritative (not authoritarian) teaching. Students have a right to wonder why they’re doing what they’re doing. It keeps me on my toes; considering if there’s a good reason for doing what we’re doing. It helps them to see how to make a rational argument — and sets, by implication, a high bar for the quality of their arguments. I also figure that if I’m respectful to them, and share my reasoning, they’re more likely to go with my decisions voluntarily, even if they don’t particularly like them.
And it seems that same approach also applies to parenting. A study (Trinkner et al., 2012) finds that adolescents respect and defer to their parents only to the extent that they see their parents as being fair, considerate and respectful of them. When kids believe that their parents’ decisions are legitimate, they are more likely to obey them. Conversely,
… authoritarian parenting was negatively associated with parental legitimacy.
— (Trinkner et al., 2012): Don’t trust anyone over 30: Parental legitimacy as a mediator between parenting style and changes in delinquent behavior over time, in Journal of Adolescence.
… authoritative parents are warm and responsive, providing their children with affection and support in their explorations and pursuit of interests. These parents have high maturity demands (e.g., expectations for achievement) for their children but foster these [through] communication, induction (i.e., explanations of their behavior), and encouragement of independence. For example, when socializing their children (e.g., to do well in school), these parents might provide their children with a rationale for their actions and priorities (e.g., “it will allow you to succeed as an adult.”). Authoritative parents score high on measures of warmth and responsiveness and high on measures of control and maturity demands…
Joseph Kony’s Lord’s Resistance Army (LRA) has been a brutally destructive force in central Africa since the 1990’s. In the last few years the Army has been decimated and pushed out of Uganda, but it still exists and is still kidnapping children and destroying families.
My former students, Sutton and Sage, brought to my attention this video from the human rights organization, Invisible Children, that is making a final push against Kony and the LRA:
BadAstronomer has posted an awesome video of the moon going through its phases for an entire year.
(it’s particularly awesome in full screen and HD.)
The video is based off a NASA webpage that will generate a picture of the moon for any hour, of any day, in the year of 2012 (and only if you’re in the northern hemisphere near the equator, but close enough). They have lots more videos and images.
Interestingly, the images are all computer generated — they’re not real photos. They are based on high-resolution images and topography data taken by the Lunar Reconnaissance Orbiter.
