Joel Cayford has posted a nice image showing the composition of the atmosphere over time — since the formation of the Earth.

Note that, although the Earth is 4.5 billion years old, and life has been around for over 4 billion years, there has only been oxygen in the atmosphere for about 2 billion years.

Oxygen is an extremely reactive gas, which is why we use it when we “burn” carbohydrates for energy. But it also means that any free oxygen added to the atmosphere would easily react with rocks, water, and other gasses in the atmosphere, so would not be available in the quantities needed for air breathing organisms until it slowly accumulated.

Also, you need a lot of oxygen in the atmosphere to produce enough ozone to form the ozone layer that protects life at the surface from high-energy, cancer-inducing, ultra-violet radiation from the Sun.

Citing this post: Urbano, L., 2012. History of the Atmosphere (from the Formation of the Earth), Retrieved May 19th, 2012, from Montessori Muddle: http://MontessoriMuddle.org/ .
Attribution (Curator's Code ): Via: ᔥ Montessori Muddle; Hat tip: ↬ Montessori Muddle.

Posted in Natural WorldNo Comments » - Tags: atmosphere, climate, environmental science, geologic history, geology

In the early solar system, 4.5 billion years ago, the planets were still coalescing, something enormous hit the Earth.

After it formed, huge impacts shaped the surface of the moon into what we see today. NASA takes up the story:

These videos are awesome introductions to the early history of the Earth, Moon, and solar system.

Citing this post: Urbano, L., 2012. The History of the Moon, Retrieved May 19th, 2012, from Montessori Muddle: http://MontessoriMuddle.org/ .
Attribution (Curator's Code ): Via: ᔥ Montessori Muddle; Hat tip: ↬ Montessori Muddle.

Posted in Natural World, videoNo Comments » - Tags: astronomy, earth history, geology, moon, solar system, video

The area around the Fulton School has just two types of geology: young, floodplain sediments; and old limestone bedrock.

• Missouri River Flood Plain Sediments:
  • The flat area next to the Missouri River that would get flooded regularly if the rivers weren’t regulated)
  • Holocene (last 10,000 years)
  • 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)

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 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.

Many of the micro-organisms that lived in that ocean made shells out of calcium carbonate.

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.

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.

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.

Citing this post: Urbano, L., 2012. The Geology of St. Albans, Missouri, Retrieved May 19th, 2012, from Montessori Muddle: http://MontessoriMuddle.org/ .
Attribution (Curator's Code ): Via: ᔥ Montessori Muddle; Hat tip: ↬ Montessori Muddle.

Posted in Natural WorldNo Comments » - Tags: geology, plate tectonics

The Earth’s magnetic field results from the movement of molten metal in the Earth’s core. The outer core actually. It’s mostly molten iron, which conducts electricity, and as it convects up and down, like boiling water in a pot, the moving electrical charges create the Earth’s magnetic field. Its a bit like a dynamo.

What drives the convection of the outer core? The heat released from the freezing of the liquid metal to the solid inner core. The inner core is ever expanding, and the outer core is getting smaller and smaller. Ultimately, when the entire outer core freezes the Earth’s magnetic field should disappear. But we’ve got some hundreds of millions of years left so we don’t have to worry quite yet.

The Other Planets

The question came up: Do Mars and the other planets have magnetic fields?

Astronomynotes has compiled a table of Planet Atmospheres and Magnetic Fields that shows that of the inner planets — Mercury, Venus, Earth and Mars — only the Earth has a significant magnetic field; Mercury does have its own field but it has less than 1% the strength of the Earth’s.

At present, Mars does not have a magnetic field, but it does have remnant magnetism imprinted on its rocks, indicating that it used to have one in the past. It’s internal dynamo died away long ago. Interestingly, the pattern of Mars’ remnant magnetism indicates that it’s interior was once molten enough that the surface had tectonic plates just like the Earth.

On the other hand, the outer planets have much larger magnetic fields; Jupiter’s is almost 20 times larger than Earth’s. The gas giants’ magnetic fields are also generated by fluid motion in their interiors (Stevenson, 1983 (pdf)). It’s likely, however, that in some of these bigger planets, at least, the electrically conductive fluid is not liquid metal like in the Earth’s core, but either liquid hydrogen, or a water solution with dissolved electrolytes.

Citing this post: Urbano, L., 2012. The Magnetic Fields of the Planets, Retrieved May 19th, 2012, from Montessori Muddle: http://MontessoriMuddle.org/ .
Attribution (Curator's Code ): Via: ᔥ Montessori Muddle; Hat tip: ↬ Montessori Muddle.

Posted in Natural World, PhysicsNo Comments » - Tags: convection, earth science, electromagnetism, geology, magnetism

Jason Shankel has an article on how we could go about changing the surface of Mars into something humans can live on. He does an excellent job of condensing the not insignificant literature on terraforming the red planet.

Starting with an explanation of Mars’ geologic history, Shankel addresses Martyn Foggs’ list of critical challenges:

1. The surface temperature must be raised
2. The atmospheric pressure must be increased
3. The chemical composition of the atmosphere must be changed
4. The surface must be made wet
5. The surface flux of UV radiation must be reduced

– Shankel (2011): How We Will Terraform Mars on io9.com.

The article is expansive in its detail, provides a wonderful primer on the red planet, and demonstrates an excellent application of planetary system science (as opposed to Earth system science) to what would be an enormous geoengineering project. For example, to warm up the planet, Shankel starts with several approaches:

so how do we warm up the Martian poles? Several approaches have been suggested, from spreading dark material on the poles to lower their albedo, to industrial ice farming to good old fashioned thermonuclear detonations.

– Shankel (2011): How We Will Terraform Mars on io9.com.

He then goes into detail. Lots of detail, in a quite readable form.

Citing this post: Urbano, L., 2011. Terraforming Mars, Retrieved May 19th, 2012, from Montessori Muddle: http://MontessoriMuddle.org/ .
Attribution (Curator's Code ): Via: ᔥ Montessori Muddle; Hat tip: ↬ Montessori Muddle.

Posted in Natural WorldNo Comments » - Tags: earth system science, environment, environmental science, geology, mars, solar system, space science

A single, half-day, visit to the landfill and quarry brought up quite the variety of topics, ranging from the quarry itself, to the reason for the red colors of the cliff walls, to the uses of the gases that come out of the landfill. I still have not gotten to the details about the landfill itself, but I’ve put together a page that links all my posts about the quarry and landfill so far.

• Quarry
• Water Cycle
• Methane Gas (CH₄)
• Hydrogen Sulfide (H₂S)
• Density (and freshwater lens)
• Iron staining on the cliffs.
• The Coal Seam.

There was so much information that we spent the better part of the following week debriefing it in the middle-school science class.

The map below gives a good aerial view of the site.

View Landfill and Quarry (as of 11/26/2011) in a larger map

Citing this post: Urbano, L., 2011. Visit to the Quarry/Landfill, Retrieved May 19th, 2012, from Montessori Muddle: http://MontessoriMuddle.org/ .
Attribution (Curator's Code ): Via: ᔥ Montessori Muddle; Hat tip: ↬ Montessori Muddle.

Posted in immersion, Immersion Overview, Natural WorldNo Comments » - Tags: environment, geology, immersion overview, landfill, my art photos, St. Louis field trips, waste immersion

The water cycle is intricately tied to all the other topics that came up on our visit to the quarry/landfill. For some things, the tie to water is direct and inextricable.

• It’s groundwater that dissolves the pyrite in the coal seam and then precipitates an orange iron stain on the quarry cliffs.
• Rainwater seeping into the landfill leaches out chemicals that have to be prevented from getting into the groundwater, rivers or lakes.
• Gases like hydrogen sulfide can react with water (and oxygen) in the air to produce acid rain. Not to mention that water is needed for the decaying processes that produce the hydrogen sulfide, and other landfill gases like methane, to begin with.

For other things the link to water is not necessarily so obvious:

• The sediment that was compressed into the limestone that is being quarried, was formed beneath the shallow seas that once covered this region in the geologic past. Limestone is also dissolved by rainwater to create caverns, underground rivers and spaces for geodes.
• Methane gas not only requires water for it to be released via decomposition of garbage, but also produces carbon dioxide when burned. Carbon dioxide is a greenhouse gas, so it affects the global temperature and contributes to the melting glaciers, rising sea levels and changes in climatic patterns such as the amount of rain we’re going to receive in the midwest.

The water cycle picture starts simply, but gets complicated very quickly.

Citing this post: Urbano, L., 2011. The Water Cycle ... at the Quarry, Retrieved May 19th, 2012, from Montessori Muddle: http://MontessoriMuddle.org/ .
Attribution (Curator's Code ): Via: ᔥ Montessori Muddle; Hat tip: ↬ Montessori Muddle.

Posted in Natural WorldNo Comments » - Tags: field trips, geology, hydrology, immersion, landfill, St. Louis field trips, waste immersion

The landfill/quarry we visited was originally a limestone quarry; once they had the hole in the ground they needed to fill it with something so why not trash (and why not get paid to fill it).

The limestone bedrock is blasted daily to create some massive boulders. The boulders are then loaded on some equally massive dumptrucks. There are scarce few minutes between trucks, so a lot of rocks are being moved.

The trucks then dump their load into a large building where the rocks are crushed. Our guide made us stop the bus to watch the process. While watching a dumptruck unloading might seem mundane, the enormous size of the truck and its boulder load did seem to captivate the students.

Once the rocks are crushed, the resulting sediment is sorted by size (sand, pebbles and gravel, I think) and piled up. The piles are massive. I’ve been wanting a good picture that shows the angle of repose; I got several.

The pebbles and gravel are used for road construction and provide a matrix for concrete.

Since limestone dissolves fairly easily in rainwater, the sand-sized and smaller particles (< 2mm diameter) aren't used for construction -- hard, insoluble quartz sand is preferred.

Limestone: calcium carbonate (CaCO₃)

However, the limestone sediment piles sit out in the open and some the finer grains (silt sized particularly), and any dissolve calcium carbonate, get washed into the nearby ponds, which turn a beautiful, bright, milky green.

Finally, in addition to the limestone sediment piles, there is also one enormous pile of broken up concrete. One of the things that stuck with the students was that fact that you can recycle concrete.

Citing this post: Urbano, L., 2011. Limestone Quarry, Retrieved May 19th, 2012, from Montessori Muddle: http://MontessoriMuddle.org/ .
Attribution (Curator's Code ): Via: ᔥ Montessori Muddle; Hat tip: ↬ Montessori Muddle.

Posted in Chemistry, Natural WorldNo Comments » - Tags: chemistry, field trip, geology, landfill, my art photos, St. Louis field trips, waste immersion