God’s Old Earth Curriculum Chapter 2: In Which We Get Our Earth Systems On

I’m seeing a pattern: the first paragraph of each of Greg’s chapters is all about establishing the Christian cred. Like so:

Our planet is perfectly designed by God to function using the physical laws that He set in place. Through these laws, the earth is constantly being modified. These laws can be seen operating in several key systems that He designed.

Image is a detail of God pointing from the Sistine Chapel. Caption says, "Look at that earth! I totally made that."

From there, God goes away, and science takes over. We’ll be exploring the hydrologic and tectonic systems, plus isostasy. We apparently won’t be indulging in endless speculation as to how God designed it all ala ES4. Part of me is relieved. Part is sad, because it makes these posts rather too easy.

So. The Hydrologic System. Greg provides a succinct summary of the water cycle, then goes on to glance over river systems, glaciers, ground water, and shorelines. He also includes air as part of the hydrologic system, and so has a section on eolian systems. I couldn’t determine if this is normally a Done Thing – I’ve never seen these systems discussed as belonging together before – but Dynamic Earth includes eolian systems under the hydrologic system, so perhaps it’s legit. It certainly made me think of the hydrologic cycle in a new and interesting way.

Tectonic systems could use some revising. Slab pull is incorrectly attributed to convection currents – it’s actually caused by a subducting slab. The mechanism that causes subduction zones isn’t explained (one slab is more dense than the other plate it’s encountering, and so it dives). The reason why continental-to-continental plate collisions cause mountains to rise is unexplained. And he incorrectly states that oceanic-to-oceanic plate convergence causes mountain ranges to rise – actually, the older oceanic plate will be colder and denser, so it will sink, and we get another subduction zone.

Greg uses subsidence around Hoover Dam to isostasy, saying the weight of the water it ponded “caused the circular area around the lake to subside about 5.5 feet (1.7 meters)” in a few years. The studies I found don’t show that. The dam was built in 1935; by 1950, the maximum subsidence was only 350 millimeters – just over a foot. There are many more causes of subsidence than isostasy there, including ground water withdrawal. Outside of those quibbles, though, we get an adequate idea of isostasy.

The research topics contain some bits that will stretch the kiddos’ noggins nicely. Along with asking when the theory of plate tectonics was first proposed and by whom, we’re also to research the North American plate, which plates it comes into contact with, and how they affect each other. We’re also asked to explore how plate tectonics relates to the San Andreas Fault. Good stuff!

Most of the quiz questions were well – designed, and the answers easy if you’d been paying attention. Question 10 was a bit tricksy, asking what isostatic adjustments are caused by. Possible answers are: radioactivity, gravity, water, and ice. After all that talk of water and ice causing subsidence, it would be easy to be fooled! But there can be only one right answer, and it is GRAVITY!

(Yes, I got 100%: ’tis easy to do when you’ve read the section literally two minutes before.)

For the test, they’ve done a good job making it necessary to read closely lest you screw up. For instance, one true-or-false question reads, “Glaciers can form when the annual snowmelt exceeds the amount of new snow that falls.” The conditions are reversed! I had to do a double take, because my brain picked out the keywords “Glaciers, form, exceeds” and screamed “True!” before going “wait, what?” That wasn’t the only one that made me work for it. Got 100% again, though, so all you have to do is read the chapter right before you take the test and have a good memory for facts, plus have mad multiple choice skillz.

In the resources links, there’s a nice news aggregate site for plate tectonics. You can amuse yourself for a bit and learn a little, too. Just remember, they’re mostly news, not research in the scientific sense.

I’m not as pleased with this chapter – too many mistakes for such a short section. It could use some correction and expansion. But I’m very happy to see a minimum of God talk and a focus on real science. Let’s hope that happy state of affairs continues.

God’s Old Earth Curriculum Chapter 2: In Which We Get Our Earth Systems On

5 thoughts on “God’s Old Earth Curriculum Chapter 2: In Which We Get Our Earth Systems On

  1. 4

    and all these plates zoomed around to their current positions in about 6K years since Teh Creation becuz Goddiddit, right?

    Sounds like this chapter could be a Thin End of the Olde Earthe Wedge if somebody isn’t careful!

  2. rq

    God just hates people who build in meteorologically and geologically unstable areas! You’d think we’d know this by now.

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