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Radiolab: The Extinction of the Dinosaurs

March 31, 2014

RadioLab has an excellent podcast featuring Jay Melosh, a geophysicist who specializes in impact craters, and who advocates the hypothesis that the entire extinction event that killed off the dinosaurs at the boundary between the Cretaceous and Tertiary (the K-T boundary) took place over a period of two hours. The asteroid impact vaporized the crust of the Earth where it hit (near the Yucatan peninsula) and blasted this rock gas into space. There it cooled down to create little glass particles that reentered the atmosphere. On reentry the glass burned up, but there was so much of it that it raised the temperature of the atmosphere by several hundred degrees Celsius. Anything near the surface (mostly the dinosaurs) was cooked, but anything living just beneath the surface could have survived.

Citing this post: Urbano, L., 2014. Radiolab: The Extinction of the Dinosaurs, Retrieved November 21st, 2017, from Montessori Muddle: http://MontessoriMuddle.org/ .
Attribution (Curator's Code ): Via: Montessori Muddle; Hat tip: Montessori Muddle.

Understanding the Extinction of the Dinosaurs (and the Survival of Mammals)

July 28, 2013

This neat paper (Robertson et al., 2013) in the Journal of Geophysical Research makes an interesting attempt to explain the pattern of extinctions that occurred at the end of the Cretaceous: why most of the dinosaurs died out, and why ocean organisms were more severely affected than freshwater organisms by the long winter after the asteroid impact.

The flow chart explains:

Diagram of contrasts between freshwater and marine environments for factors potentially causing extinction in aquatic environments after the Chicxulub impact. (Image and caption from Robertson et al., 2013).

Diagram of contrasts between freshwater and marine environments for factors potentially causing extinction in aquatic environments after the Chicxulub impact. (Image and caption from Robertson et al., 2013).

They also include an interesting figure showing how long an organism might survive based on how large it is, which I may be able to use in pre-Calculus when we’re discussing log scales and linearizing equations.

Allometric relationship between body size and time to death by starvation for multicellular poikilotherms in the absence of food (red, drawn from the equation of Peters [1983, p. 42]). Names of various types of organisms are shown as an indication of body size. Image and caption from Robertson et al., 2013.

Allometric relationship between body size and time to death by starvation for multicellular poikilotherms in the absence of food (red, drawn from the equation of Peters [1983, p. 42]). Names of various types of organisms are shown as an indication of body size. (Image and caption from Robertson et al., 2013.)

The article is written well enough that an interested high school biology student should be able to decipher (and present) it.

Citing this post: Urbano, L., 2013. Understanding the Extinction of the Dinosaurs (and the Survival of Mammals), Retrieved November 21st, 2017, from Montessori Muddle: http://MontessoriMuddle.org/ .
Attribution (Curator's Code ): Via: Montessori Muddle; Hat tip: Montessori Muddle.

Edna St. Vincent Millay and the extinction of the dinosaurs

September 24, 2010

Travel
by Edna St. Vincent Millay

The railroad track is miles away,
And the day is loud with voices speaking,
Yet there isn’t a train goes by all day
But I hear its whistle shrieking.

All night there isn’t a train goes by,
Though the night is still for sleep and dreaming,
But I see its cinders red on the sky,
And hear its engine steaming.

My heart is warm with friends I make,
And better friends I’ll not be knowing;
Yet there isn’t a train I wouldn’t take,
No matter where it’s going.

I discovered today, during our morning poetry reading, that Edna St. Vincent Millay‘s poem Travel is a metaphor for the asteroid collision that caused the extinction of the dinosaurs. The train is asteroid bearing down on the Earth, the smoke from the train is the dust and ash kicked up by the impact, while the whistling of the train is the moan of the dying dinosaurs.

Remarkably perceptive of St. Vincent Millay since the asteroid impact theory was posited by the Alverezs’ group decades after her death in 195.

Citing this post: Urbano, L., 2010. Edna St. Vincent Millay and the extinction of the dinosaurs, Retrieved November 21st, 2017, from Montessori Muddle: http://MontessoriMuddle.org/ .
Attribution (Curator's Code ): Via: Montessori Muddle; Hat tip: Montessori Muddle.

Oil does not come from dinosaurs.

August 3, 2010

Phytoplankton (image from NASA).

There’s a nice article in the New York Times on the fact that oil, petroleum, did not come form dead dinosaurs, but rather from the microscopic plankton that died and fell to the ocean floor.

The idea that oil came from the terrible lizards that children love to learn about endured for many decades. The Sinclair Oil Company featured a dinosaur in its logo and in its advertisements, and outfitted its gas stations with giant replicas that bore long necks and tails. The publicity gave the term “fossil fuels” new resonance. – Broad, 2010

It’s easy to forget how pervasive is the idea that oil comes from dinosaurs. Broad’s article is a nice reminder that:

Today, a principal tenet of geology is that a vast majority of the world’s oil arose not from lumbering beasts on land but tiny organisms at sea. It holds that blizzards of microscopic life fell into the sunless depths over the ages, producing thick sediments that the planet’s inner heat eventually cooked into oil. It is estimated that 95 percent or more of global oil traces its genesis to the sea. – Broad, 2010

How do we know?

[I]n the 1930s. Alfred E. Treibs, a German chemist, discovered that oil harbored the fossil remains of chlorophyll, the compound in plants that helps convert sunlight into chemical energy. The source appeared to be the tiny plants of ancient seas. – Broad, 2010

Phytoplankton bloom off the Carolina coast. (Image from NASA).

We tend to find a lot of oil in the deltas of the great rivers because the rivers provide nutrients for the microorganisms to survive and layers of sand and clay sediments that trap the oil and natural when they’re produced.

The article also ties the location of oil production to the geography of plate tectonics.

[W]hen Africa and South America slowly pulled apart in the Cretaceous period, forming the narrow beginnings of the South Atlantic. Big rivers poured in nutrients. A biological frenzy on the western shores of the narrow ocean ended up forming the vast oil fields now being discovered and developed off Brazil in deep water. – Broad, 2010

Citing this post: Urbano, L., 2010. Oil does not come from dinosaurs., Retrieved November 21st, 2017, from Montessori Muddle: http://MontessoriMuddle.org/ .
Attribution (Curator's Code ): Via: Montessori Muddle; Hat tip: Montessori Muddle.

Assessment with the Toilet Paper Timeline of Earth History

December 17, 2012

With a larger class, and quite a bit of space in the gym, I had more flexibility working on the toilet paper timeline compared to the last time.

Labeling the timeline in the gym.

I built in a friendly race to see which group could find a set of events first, and allowed me to highlight nine different, important, series of events along the timeline.

The adapted spreadsheet, racing sequences, and a short summative quiz are on this Toilet Paper Timeline spreadsheet.

I broke the class up into 4 groups of 4, and each group created their own timeline based on a handout.

Groups of students lay out their toilet paper timelines. Post-it notes were used to label the events.

Then, I gave each group a slip of paper with four events on it (one event per student), and they had to race to see which group would be first to get one person to each event on the list. Once each group got themselves sorted out, I took a few minutes to talk about why the events were important and how they were related.

Table 1: The series of events.

1) We’ll be talking about plate tectonics soon, so it’s good for them to start thinking about the timing of the formation and breakup of the supercontinents.
Event 1 Event 2 Event 3 Event 4
Formation of Rodinia (supercontinent) Breakup of Rodina Formation of Pangea Breakup of Pangea
2) This sequence emphasizes the fact that most free oxygen in the atmosphere comes from ocean plants (plankton especially), and that a lot of free atmospheric oxygen was needed to to form the ozone layer which protected the Earth’s surface from uv radiation, which made the land much more amenable to life. Also, trees came way after first plants and oxygen in the atmosphere.
Event 1 Event 2 Event 3 Event 4
First life (stromatolites) Oxygen buildup in atmosphere First land plants First Trees
3) Pointing out that flowering plants came after trees.
Event 1 Event 2 Event 3 Event 4
First life First land plants First trees First flowering plants
4) The Cambrian explosion, where multicellular life really took off, happened pretty late in timeline. Longer after the first life and first single-celled animals.
Event 1 Event 2 Event 3 Event 4
First life (stromatolites) First animals First multicelled organisms Rise of multicelled organisms
5) Moving down the phylogenetic tree from mammals to humans shows the relationship between the tree and evolution over time.
Event 1 Event 2 Event 3 Event 4
First mammals First Primates Homo erectus Homo sapiens
6) More tectonic events we’ll be talking about later.
Event 1 Event 2 Event 3 Event 4
Opening of the Atlantic Ocean Linking of North and South America India collides with Asia Opening of the Red Sea
7) Pointing out that life on land probably needed the magnetic field to protect from the solar wind (in addition to the ozone layer).
Event 1 Event 2 Event 3 Event 4
Formation of the Earth First life Formation of the Magnetic Field First land plants
8) Fish came before insect. This one seemed to stick in students’ minds.
Event 1 Event 2 Event 3 Event 4
First Fish First Insects First Dinosaurs First Mammals
9) Mammals came before the dinosaurs went extinct. This allowed a discussion of theories of why the dinosaurs went extinct (disease, asteroid, mammals eating the eggs, volcanic eruption in Deccan) and how paleontologists might test the theories.
Event 1 Event 2 Event 3 Event 4
First Dinosaurs First Mammals Dinosaur Extinction First Primates

The whole exercise took a few hours but I think it worked out very well. The following day I gave the quiz, posted in the excel file, where they had to figure out which of two events came first, and the students did a decent job at that as well.

Citing this post: Urbano, L., 2012. Assessment with the Toilet Paper Timeline of Earth History, Retrieved November 21st, 2017, from Montessori Muddle: http://MontessoriMuddle.org/ .
Attribution (Curator's Code ): Via: Montessori Muddle; Hat tip: Montessori Muddle.

Surviving the Anthropocene

June 27, 2011

Styrofoam cup collected from the beach of Deer Island. The city of Biloxi sits in the background.

65 million years ago, an asteroid hit the Earth just off the Yucatan Penninsula, kicking up enough dust in to the atmosphere (and perhaps setting off supervolcanos) to lead to the extinction of the dinosaurs. Geologists mark this mass extinction event as the end of the Cretaceous period and the beginning of the Tertiary; it’s called the K-T boundary. Paleontologists see a rapid change in the forms of life fossilized in the rocks above and below the boundary. The element iridium, which is relatively common on asteroids, but rare on Earth, can be found in a thin layer of the fallout from the asteroid impact all around the world.

The Chicxulub Crater, believed to be the location of the K-T asteriod impact. Image from NASA: Short (2010)

Well, the Earth’s going through another mass extinction event right now. In fact, even if humans were to go extinct right now, the remains of our cities and our impact on the global chemical cycles, will leave a distinct signature that geologists millions of years from now will be able to detect.

Geologists refer to the last 10,000 years, the period starting when the Earth warmed after the last glacial maximum, as the Holocene. This time period saw the emergence of agriculture, the rise of human civilization, cities, nuclear weapons, the internet. Now, given the enormous environmental changes we’re wrecking on the planet, some say we’ve entered a new geologic epoch that they’re calling the Anthropocene.

The question is: How long will it last?

Regardless of your philosophy, the recognition that we have entered a geologic age of humanity raises the obvious question of just how long such an age will last.

In the infamous KT boundary geologists can see evidence for a rather short-lived event that also reshaped the planet. Sixty five million years ago an asteroid struck the Earth, driving one of only five mass extinctions in the planet’s history. The loss of the dinosaurs turned out to be an opportunity for our mammal ancestors and led directly to our own age.

Since the Anthropocene appears to mark a sixth great extinction, one has to wonder what it will take for us to make it out of own era with civilization intact.

— Frank (2011): The Anthropocene: Can Humans Survive A Human Age?

Citing this post: Urbano, L., 2011. Surviving the Anthropocene, Retrieved November 21st, 2017, from Montessori Muddle: http://MontessoriMuddle.org/ .
Attribution (Curator's Code ): Via: Montessori Muddle; Hat tip: Montessori Muddle.

Finding meaning in children’s poetry

October 22, 2010

The gingham dog and the calico cat
Side by side on the table sat;
‘Twas half past twelve, and (what do you think!)
Nor one nor t’other had slept a wink!
– From “The Duel” by Eugene Field

Metaphor for the cold war?

Children’s poetry can be simple yet contain intricate, layered meaning. Project Guttenberg has a number of nice poetry collections available. Since they’re free it’s mostly older stuff, but human nature hasn’t changed that much in the last few hundred years.

Mary E. Burt’s 1904 collection, “Poems Every Child Should Know“, contains quite the number of classics like the one excerpted above. I like it a lot because when we talk about themes and issues in texts it is usually better to start with things that are very obvious, with simple language and simple sentence structure, to reduce the cognitive load.

However, just because the language style is simple doesn’t mean we can’t very quickly get to the complex.

The meaning of art is partially, at least, subjective, depending on the values and experiences brought to by the individual. Thus we have Edna St. Vincent Millay writing about the extinction of the dinosaurs.

So. If we read “The Duel” one morning while during the cycle when we discuss the Cold War and Mutually Assured Destruction, will students make the connection?

I hope they do, because then we can broaden the context and talk about human nature and the power of the classics.

Citing this post: Urbano, L., 2010. Finding meaning in children's poetry, Retrieved November 21st, 2017, from Montessori Muddle: http://MontessoriMuddle.org/ .
Attribution (Curator's Code ): Via: Montessori Muddle; Hat tip: Montessori Muddle.

Reading poetry in the morning

September 25, 2010

Poetry Speaks

Mrs. Z. donated two small books of poetry, The Best Poems Ever and Poetry Speaks (much thanks). The second comes with an audio cd, where many of the poems are read by the authors. Since some of the authors are adolescents themselves, their reading can be a little halting, but there is a nice authenticity.

The Best Poems Ever

The The Best Poems Ever has a lot of the classics. I read William Blake’s The Tiger as an example. The students though my reading was pretty lifeless so I recited it for them with a lot of emphasis and hand motions. They were pretty impressed that I’d memorized the poem so quickly, at least until I told them I’d memorized it years before (probably in middle school actually). I probably should have kept this secret. Sometimes you need the mystique.

We’ve come up with a schedule so someone different will read every morning at the end of community meeting. They’re required to choose their poem ahead of time and have practiced reading it before they present. We also take a little time for comments, the objective is to try to identify the issues and the subtexts. This is how I discovered, with much reasoned explanation, that Edna St. Vincent Millay metaphorically described the asteroid impact theory for the extinction of the dinosaurs over 30 years before scientists came up with the idea.

Citing this post: Urbano, L., 2010. Reading poetry in the morning, Retrieved November 21st, 2017, from Montessori Muddle: http://MontessoriMuddle.org/ .
Attribution (Curator's Code ): Via: Montessori Muddle; Hat tip: Montessori Muddle.

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