Oil traps and deltas in the sandbox

sandbox-colored-sand — Red and green sand added for marker beds.

The sandbox was built to be a wave tank so we could look at interference patterns and wave properties. But if you tilt it a little, and put in a few holes on the lower end, you can get sandbox to look at the formation of streams, deltas and the sedimentary layering that traps oil and natural gas.

Using the holes at the bottom end the students started with a low “sea-level”, raised it and lowered it. At the end of the run, they drained all the water and sliced the tank to see the depositional layers in cross-section.

We added red and green sand to try to make marker beds before each change in base level. The marker beds worked reasonably well, but it would have been better to have sand with different densities that could be sorted by the stream flow and depositional environment. It also helps to get the colored sand wet, to make a slurry, otherwise the grains will float on the water.

The shifting lobes of the delta showed up very well (see the animation) and some nice river features showed up as well. What I want to do sometime is to have students build coastlines and have waves erode them away creating typical coastal features.

My students were even able to demonstrate the tank for their presentation, because it really only takes half an hour to get all the features if you know what you’re aiming for.

Sources

The exercise these results are based on is posted as The Geology of Oil Traps Activity.

Methane hydrates for energy

Despite the fact that methane is a powerful greenhouse gas itself and burning it produces carbon dioxide there is currently quite a bit of research on extracting methane hydrates from the sea floor as an alternative to the traditional fossil fuels because there is just so much of it. Discovery Channel has an interesting video on the topic where they burn some methane hydrate ice.

Methane releases from the arctic and sea-floor could also trigger rapid climate change. Recent discoveries suggest that global warming is warming the arctic so much that the permafrost is melting an releasing a lot of methane into the atmosphere. If the arctic atmosphere continues to warm, more methane will be released, causing more warming …. This positive feedback loop would accelerate global warming. Some scientists worry that warmer ocean waters can melt methane hydrates at the sea floor releasing them into the atmosphere in a similar positive feedback loop.

Solar convection towers

Solar updraft tower. (From Mediawiki Commons)

Discovery Channel has a nice video on using a large tower, set at the center of a large greenhouse in the dessert, to generate thermal convection to power electrical turbines.

Solar cells

How do solar cells (photovoltaic cells) work? There are very simple explanations, but you can probably find a video with any level of complexity you might want.

This video from the U.S. Department of Energy is fairly general and makes a nice introduction:

This video adds some useful detail.

For even more detail, NASA’s page on photovoltaics is very good, and Scientific American has a neat little interview with Paul Alivisatos that goes into the parallel between photovoltaic technology and photosynthesis.

Simple animations about different energy sources

The UK Science Museum has a set of very simple videos describing how different sources of energy are created and harnessed. They are very simplified but perhaps useful introductions to how things like solar cells work; how oil and natural gas form; what is fusion and how it might be harnessed; how tidal power works etc.

Video games and real war

“It’s going to be a constant question for us as a society and for the military whether or not, as they become more game-like, that creates an effect that makes it easier to kill people in a way that you might not want to make it easier to kill people.” – Clive Thompson on On The Media (2010)

On The Media had one of the most though provoking pieces this weekend that I have ever heard. It was based on the video footage of the tragic killing of two Reuters journalists in Baghdad, and the wounding of two small children in a van that came to rescue the injured, by a US helicopter gunship. The program dealt with the tragedy itself, the question of war crimes and the propriety of Wikileaks in publishing the video.

They also addressed the marked similarities between the video footage and scenes in modern video games. What was most interesting was that the interviewee, Clive Thompson, argued not that video games were becoming too much like war and desensitizing players, but that war is becoming too much like video games.

It’s been generally acknowledged that the further away the person is, the less you can see them, the more they’re just a blip on the screen, the easier it is to pull the trigger. – Clive Thompson on On The Media (2010)

Audio of the piece called “Virtual War” is below:

About The Elegant Universe

NOVA’s program The Elegant Universe has an excellent website where the entire three hour video is available for free (with a full screen option). They have also broken the video up into segments and have a great teachers’ page which summarizes what’s in each segment.

Created in 2003, when string theory was making it’s big splash in the popular consciousness, The Elegant Universe starts with Newton’s observations of gravity, shows Einstein’s separate explanations of why gravity works and the nature of the sub-atomic world, and finally delves into string theory which tries to reconcile Einstein’s two theories into a unified whole.

We don’t usually get past Newton in middle school, but this PBS program introduces such a wider and weirder view of the universe that it can help strike the imagination. It also presents complex concepts in an intelligible way.