There comes a point when, during the perusal of an ACE Science PACE, the brain bluescreens. The system shuts down for self-protection. It’s usually at about the point where you’ve encountered the umpteenth wrong thing in as many sentences, and you begin wondering how any adult can be so bloody fucking ignorant. You suddenly realize that more than one bloody fucking ignorant adult was involved in writing this pablum. And you begin to consider that some of the children being subjected to this shit will never recover, but will someday regurgitate this shit with updated pictures and errors, then expect a whole new generation of kids to lap it up. This is about the point where the brain crashes.
It’s hard to get through without multiple system failures, is what I’m saying.
The writers of PACE 1086 remain incorrigibly ignorant as they go on putting atrociously-written words in Mr. Wheeler’s mouth. They know very little about metamorphic rocks, but what they do know, they repeat damned near endlessly. What metamorphic rocks need to form is “heat and pressure.” “Pressure and heat.” “The most important factors are pressure and heat.” We’re told about the pressure and heat 5 times in 3 paragraphs. There are forces, people. Tremendous ones. Causing heat and pressure. Which causes metamorphic rocks to happen.
Now, you may be asking: Where’s the strain? Hydrothermal fluids? How about contact metamorphism, where the rocks are baked but not squished? Sure, this stuff needs to be simplified for kids, but it’s not that hard to give a more complete picture. Unless you’re a religious fanatic who has only the most tenuous of grasps upon basic geology and is so busy relating metamorphism to becoming a good little fundie Xian that you can’t be arsed with scientific details.
“Mr. Wheeler,” commented Racer, “this talk of rocks being changed reminds me that many of my thoughts and actions were changed when I became a Christian. Even now, I find my life still being changed when I learn more principles from God’s Word.”
Yes, that’s right: five tiny paragraphs in, and they’re babbling about metamorphosing into godbots, forgetting about the rocks they’re supposed to be discussing.
These folks are horribly sloppy. They imply metamorphism’s all about minerals melting (not quite), and then go on to imply that metamorphic rocks are everywhere:
“If you know the general type of igneous or sedimentary rock that occurs in an area, you can expect to find the metamorphic rock into which that type of rock is changed.”
Um, no, you can’t. You’ll only find metamorphic rock where conditions have favored its formation. And the rocks found near metamorphic rocks aren’t always related to them. Both Hutton’s Unconformity at Siccar Point and the Great Unconformity in the Grand Canyon are great examples: the sedimentary rocks are completely unrelated to the metamorphic rocks they lie upon.
Next, we’re treated to a long lecture about the things you can use different kinds of metamorphic rock for. This goes on and on for over a page and a half in a book that’s only 31 pages long. Even there, they fuck up, babbling about how “quartzite grains” are used to make sandpaper. Naw, dawg. It’s quartz. Just simple, honest quartz sand-hence, sand paper. And actually, good old corundum is what’s most commonly used in “sand” paper today.
But it’s when they get to schist that the bullschist runs deep:
“Schist is one variety of igneous metamorphic rock¹. ‘Schist’ means ‘readily split.’² Schist breaks easily into very thin layers, or sheets.³ Mica is a common type of schist.4 Mica schist can be separated into thin, glass like sheets.5 It may be colorless, or may have many different colors.6 Mica schist may be used in roofing and insulating materials.7“
I don’t think there’s a single accurate sentence.
- Schist can come from igneous rock, but most schists are sedimentary in origin.
- “Schist” just means “split.” It’s a nit, but damn it, I’m picking it.
- Ummm… It can break easily. Sometimes. But “very thin?” “Sheets?” Oh, dear, I believe someone’s confusing a mineral with a rock.
- Mica is a mineral. It’s a component of schist, sometimes; not the whole of the thing.
- No, that’s pure mica, you dunderhead. Mica schists don’t act like that unless they’re nearly pure mica. You’re confusing a mineral for a rock again.
- And again! Schist isn’t colorless, for crap’s sake.
- AND AGAIN! The mineral mica is used in such materials. Not the rock mica schist.
I suppose it’s a mercy they used the right photo…
Damn it, brain bluescreened again. BRB.
They next proceed to prove they know nothing about gneiss. It’s an “igneous metamorphic rock,” they say. Aside from the sloppy phrasing, they leave out the fact gneiss can also originate from sedimentary rock. And it doesn’t form when “crystals in the granite” “melt together.” That would be an igneous rock – metamorphics don’t form from melts. Gneiss is more complicated: it requires high temps, yeah, but high pressures, and lotsa shear stress. This is not a simple rock formed by melted crystals.
Now they’ve screwed up just about everything, they go on to talk about conglomerate. Yep – Conglomerate. The sedimentary rock. Yep, just plain ol’ conglomerate, not the meta version. Yes, we are, still, in the metamorphic section. No, I don’t know what conglomerate is doing in the metamorphic section, either. It makes as much sense as their subsequent yammering about Jesus talking about building on a rock which is actually the Bible. But Jesus is another kind of rock. And so on. For nine paragraphs.
It’s a good thing that’s the end of the metamorphic rock section, because my brain has bluescreened again, and when I tried to reboot, it said “Fuck You.” and shut down completely.
I think we’ll go back to the other Christianists books for a bit. They’re painful, but they’re not fatal to brain function.
Well, not completely fatal.
One thought on “(Repost) Adventures in ACE X: Misinformed About Metamorphic”
They couldn’t even bother to find a pretty piece of mica schist. Grumble.
The thing about metamorphism is that the mineral compositions of the rocks change. You actually get chemical reactions induced by various combinations of heat and pressure, which transform the minerals of igneous and sedimentary rocks into other minerals that are quite different.
The other important issue is that, except for contact metamorphism, metamorphic reactions take place deep underground. Where else do you get the pressure-temperature combinations required? So, if you’re seeing metamorphic rocks at the surface, there’s been some significant tectonic activity happening in the vicinity. They had to get back up to the surface somehow.
And finally, I have to share that I’ve seen pure mica sheets in a geology lab. Amazingly cool stuff. I have no idea where the sample was collected. But mica in most rocks occurs in small to miniscule crystals. They’re easiest to see in igneous rocks; go down to your local shop that sells “granite” slabs for countertops, and look at the back side of the slabs out in the yard. Most of the igneous materials will have flashy little rectangular crystals in them. That’s probably mica. However, mica can and does form in metamorphic rocks that have sedimentary precursors as well as igneous precursors. A little heat, a little pressure, a whole host of possible chemical mixes, and mica forms. It’s the volunteer whose hand shoots up at every opportunity.
Comments are closed.