Monday, January 24, 2011

Why Geology and the Earth Sciences Count: Teaching at a Community College


So what was Geotripper doing providing advice on human relationships on a geology blog yesterday? Randy got it exactly right, I was teaching chemistry! Haven't you ever wondered what holds the world together, how a bunch of supermicroscopic atoms can stick to one another and form such beautiful rocks and minerals? A great many people might be interested in knowing, but feel intimidated by the level of knowledge seemingly required to understand such things. To understand a crystal, one needs to know of protons, electrons, neutrons, elements, and bonding. To fully understand an earthquake or a tsunami one needs some basic understanding of the behaviour of waves. To understand the twinkling of a star in the sky, one needs some grounding in the nature of the electromagnetic spectrum. It is a tall order, but not impossible. The knowledge is there for anyone to comprehend if they wish to...I will explain the specifics of our Dear Gabby advice at the end of this post.

Geology and the earth sciences occupy a special place in the academic universe. They are the very tangible examples of chemistry and physics at work in the real world. Not the strange world of atoms and smaller objects where Newtonian physics falls apart into strange new rules. Not the vastness of an unimaginably strange Universe. It is the ground beneath our feet, the flooding of a nearby river, the shock of an earthquake, the price of gasoline at the local pump. It is the prediction of next week's snowstorm, the drought of the next decade, and sea level rise in the next century. It is the planning for the end of an oil economy. An understanding of the earth sciences is critical to making the best choices in resource use and allocation in an overpopulated world.

National parks and monuments are not generally established because they preserve some aspect of physics and chemistry. If they don't preserve a historical battleground or unique plant or animal, they are there because something of geology is worthy of our interest and protection. We may photograph the bears, deer and squirrels that inhabit Yosemite, Yellowstone or Grand Canyon, but the meaning of the parks is in the rocks. The squirrels live everywhere, but the geysers, rock strata and gorges make these places unique. Communicating the meaning and value of these parks to society is prime concern of the park's interpretive rangers.

That brings us to the challenge. To be a geology/earth science major, one needs to be a real polymath, a Homo Universalis (look it up! I had to). It is generally recognized that the candidate needs to master calculus, physics and chemistry, usually in classes that has him or her competing directly with actual math, physics and chemistry majors. It is not the easiest major to pursue. In an ideal academic world, the geo-major would have prerequisites in all of these listed fields before ever setting foot in a physical geology course.

This is not feasible or possible in my world of the community college. A prerequisite like that would leave me with three or four students each semester (hmmmm....that's a thought). Our community colleges serve many constituencies and few of my students will actually end up as majors. They will become teachers, nurses, accountants, firefighters, small business owners and so on. They take a geology/earth science class for many reasons, but most often because it is one of the listed physical science lab electives they need for their general education requirements. Our goal is not to produce geologists and earth scientists (although it is nice when that happens), but to produce an informed community of educated citizens.

So, I have the challenge (and privilege) of assisting my students in understanding some basic principles in physics and chemistry without getting bogged down in aspects of the sciences that they won't need in order to understand introductory geology. Chemistry is covered in about 2 hours and 40 minutes. The boiled down version of chemistry that I present would probably appall my colleagues down the hall, but they will have time to fix it when my students take a chemistry course a semester or two later. In the meantime, the students will have more than enough to try and understand; why not make it as memorable as possible?

They tell us we should not anthropomorphise inanimate objects like atoms (atoms don't "want" to do anything or "behave" in a particular way, they just act according to the laws of physics). But that sort of takes the fun out of explaining atomic activity.

So...atoms are in fact couch potatoes, in the sense that they exist and react in such a way as to maintain a stable low energy state. This generally involves having a specific number of electrons in the outer energy shells. They achieve the stable outer shells by giving up or taking in electrons from the local environment, i.e. from or to other nearby atoms. This leaves atoms in an ionized state, meaning they now have a positive or negative charge. The oppositely charged particles are attracted to each other to form an ionic bond.

Other atoms achieve stability by merging their orbiting electron shells and sharing the fast moving particles. Such outer-shell electrons are called valence electrons, and the bond is a covalent bond.

In some minerals like gold, silver or copper, the electrons flow freely throughout the solid and are not tied to any specific atoms, a so-called metallic bond (ever wondered what electricity actually is?).

And as Randy points out, the noble gases already have filled outer electron shells, so they don't react or bond with other atoms at all. These elements include helium and argon gas. A moment of truthfulness here: I was actually thinking of the very weak Van der Waals bonds, but the example of the noble gases works much better as a metaphor of non-commitment!

The next step is to understand how these bonds lead to the formation of the crystals (and crystalline solids) we find scattered throughout the crust of the earth (such as the amethyst quartz above). I love crystals, not for spiritual new age reasons, but for the assurance they provide us that there is order in the Universe. They are beautiful reminders of the accomplishments of atomic couch potatoes seeking that nirvana of the lowest energy state possible.

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