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I can't find the pre-Isuan sequence defined anywhere. Have googled--three hits, but no explanation other than what I already knew: the sequence is part of the Hadean Era.
Have checked Onelook.com. Neither pre-Isuan nor Isuan is defined.
Checked Brittanica online. Nada.
Does this mean I'm going to have to go to a 3D library and actually find something in a book? Aggggghhhhhh! I'm being facetious--I love libraries.
Anyway, if anybody knows what the sequence is exactly--what occurred during the sequence specifically, many thanks.
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formerly known as etaoin...
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Thanks, Et'. I'd read through two of your three last weekend. Here's the phrase that's out there on the Internet: "The name Hadean was coined by geologist Preston Cloud for the pre-Isuan sequence whose record may not be preserved on Earth but is better known from Moon rocks." But I cannot find 'pre-Isuan sequence' defined anywhere. I'm investigating the Hadean Era, the first geologic period of the Earth's existence, even though we have very few rocks from the period, most being Moon rocks and meteorites that are as old as 4.5 Ga. There's controversy in the theories about the Hadean Era--just how long the Earth was hot; whether it can be proven that the Earth went through long 'snowball' periods during the era; why we have no actual geological evidence from this first era--and whether we might have such evidence. I read one research project out of Stanford last weekend in which the molten heat of Hadean Era Earth had been questioned--the Sun's heat at that time having been cooler than it is today. Interesting study. But nowhere can I find the term 'pre-Isuan' defined--and it's only mentioned in conjunction with Preston Cloud's having named the first era 'Hadean' (after 'Hades' or place of great heat  ). So that's that. Looks like a trip to the library today is in the offing.
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did you try a search of "geologic sequences"? might not give specifics for the pre-Isuan, but might be worth a shot... cool stuff...
formerly known as etaoin...
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Pooh-Bah
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WW, there isn't much on the pre-Isuan period because not much is known about it except by extrapolation from meteorites and moon rocks and a few bits and pieces of rock which may or may not be as old as they are thought to be. The Isuan itself was defined when some gneiss rocks from the Archean period were found in Greenland. These are the earliest rocks found on Earth, I think, although you're now stretching my memory here although not quite for 4.5b years.
There is still, I think, some argument about whether any of the pre-Cambrian "divisions" actually mean anything in terms of time lines, since there is no meaningful way of dating the rocks. Most of the dating for later geologic periods depends very much on the fossil record. No fossils, no "accurate" dating. Therefore anything earlier may have been in the proposed sequence, or they may all have existed together.
I hope your library can help!
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WW, your search led me to this intriguing site; I think you and all your music-teacher colleagues ought to institute this rite, or something similar, every Thursday!  It's a bit of a challenge to wade through the typos, but most of it's pretty clear. I particularly like preparing lustral water . http://www.mahidol.ac.th/Thailand/art/teacher.html
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Nothing at the library at all about the 'pre-Isuan sequence.' It's this 'sequence' term that really has me curious--a sequence is a series we can follow, whether theoretical or otherwise. I'd like to know what the pre-Isuan sequence is.
I think I'll run this one past a colleague's husband next week. He's a professor of geology at a local college.
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I think I've just answered my own question. Here's what I wrote to an online geologist:
"During the last week, I've read many articles on the Internet about the Hadean Era. The specific phrase "pre-Isuan sequence" keeps coming up on several sites in relation to Mr. Cloud's having named the era. I realize that Isuan ('Izuan') is an early geologic period. But what I cannot find is any information about what this 'sequence' is--the so-called 'pre-Isuan sequence.' Does that simply refer to the series of periods subsumed by the Hadean Era that precede the Isuan (Izuan) period?
Thanks in advance for the favor of a reply."
*Thanks Et', Cap' and Jack'--your information definitely confirmed what I'd collected.
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Pooh-Bah
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It's a geological "sequence"; that is, it is the order in which rocks were formed. To call the pre-Isuan a sequence is pushing it a bit far probably, since they don't have much evidence for its existence, never mind a sequence. But I guess there logically must have been one regardless of whether or not they can find any evidence!
Be interested to hear what your tame professor says, WW.
Getting on for 25 years since I studied geology, though. I do try to keep up, but they find new stuff alla time ...
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Yep, Cap'--it's starting to sink in. The order of rock sequences. There are those larger periods of time that subsume other periods in all the geological periods, so that's what I figured out last night--that the periods umbrella'd by another would be commonly referred to among geologists as 'sequences.' Then they would easily refer to any sequence they wanted to as pre- or post-.
There it is: vocabulary all over again. Once you have the vocabulary of a discipline down pat--the vocabulary and sometimes syntax, too--reading within the discipline becomes so much easier. In fact, that is something I'll have to work on with students next year, a 'standard of learning' in Virginia for writing--having kids recognize and learn vocabulary in the specialized areas they have to read and write about.
We'll see whether the Internet professor responds--and I'll also ask my colleague at school to ask her husband.
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Thank you for the informative thread, Dub-Dub! And for that detailed geologic Time Chart, eta! I rarely see thew chart broken down into the smaller sub-divisions. And, usally, being more concerned with the organic aspects of the geologic time periods most paleontological charts simply designate everything before the trilobite fossil record as Pre-Cambrian. However, this discussion reminded me of a post I've been meaning to make about the current, and increasingly-proliferous use of the term dead dinosaurs as a kind of euphemism in referring to oil. First of all, the bulk of the oil deposits were formed during the Carboniferous period, almost 50 million years before the appearance of the dnosaurs, from the remains of decayed plant life, the lush tropical forests, including giant ferns, that covered the earth at that time on what was mostly an expansive swamp. It is estimated that at least 70% of all extant oil deposits were created at this time. There were amphibians and sea life, and some reptiles did begin to appear at the end of this period, and *some of their remains may account for a minisule portion of the oil deposits of this period, but the bulk were formed from decaying flora (including alagae). Oil was formed from the organic matter that collected at the bottom of the swamps and sea (and other bodies of water), and coal was formed from plants that died on land. But "dead dinosaurs" to describe oil seems to have been adopted by the print and broadcast media, and it's use is gaining much frequency. It probably started when some ill-educated reporter decided it made for a cute and nifty turn of phrase (akin to "dead presidents" for US money), and some clueless editor let it go. But for a phrase of such geologic and scientific inaccuracy to be gaining popularity (and seeing as how that most people don't bother to study or delve into paleontologic or geologic data in this post-literate society), the adoption of this phrase will likely turn the misinformation that oil is "dead dinosaurs" into a "scientific" fact in most people's minds. Here's the clearest breakdown of the formation of oil I could find: http://www.gcsechemistry.com/o1.htmAnd here's a bit more extensive look that attributes most of the oil deposits to the Carboniferous period: http://www.energyquest.ca.gov/story/chapter08.htmlA much smaller percentage of oil depostis is said to have formed later, right on into the Mesozoic era. So there is probably a small percentage that came from *some remains of pleisiosaurs and other sea dinosaurs. So the coiners and users can point to that to rescue the use of their phrase as *partially accurate. But it is *largely inaccurate. And to say that oil is "dead dinosaurs" is just wrong.
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I imagine the dinosuar bit evolved (heh) from the term fossil fuel; could have, anyway. For a slightly (ahem)different view of oil from the earth, go to: http://www.astridmm.com/prouty/coment13.htmlI tried looking up who that guy is; found a very brief bio, but.
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Pooh-Bah
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Phew, well that's all right then. There was silly me, worrying that we would run out of oil ...
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Fletcher Prouty. Interesting point of view, Jackie. There's so much down there deep below. Let's see. I read something this past winter about the liquid (mostly iron) part of the Earth's core. The core is part mostly liquid iron and the other part of the core is mostly solid iron, just to keep this comment simple. Anyway, the liquid outer core is increasing in size--very slowly--but increasing. That's food for thought.
So it's not too much of a stretch to imagine this organic oil creature-oid increasing within the Earth at some level rather than decreasing--even though we may be using it at levels greater than the level at which it is increasing. mind. Bogus or not, it's still fun imagining Prouty's observations on some impossibly plausible level.
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veteran
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There was a commercial back in the late 70s or early 80s that somehow showed a cartoon dinosaur being transmuted into oil. I can't remember the details. But I also think maybe the sequence of evolution is not understood so well even by many people who believe it. Probably most adults are at least aware of the mass extinction that killed off the dinosaurs. Probably very few are aware that the Permian-Triassic dying was much worse ( http://www.bbc.co.uk/education/darwin/exfiles/massintro.htm . Probably anyone who has taken college geology would know this, but geology is not a required course for most students. It just takes a while for scientific information to percolate through the general consciousness. k
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The Extinction Files
Great site, FF...thanks!
As George Carlin once said, "Environmentalists and other folks are always so alarmed when a species disappears, that extinction is so final. But it's not like it hasn't happened before. The world's gonna be just fine. I mean, the Earth isn't going anywhere......we are going away!"
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old hand
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slightly (ahem)different - too nice to be true, alas. There are solid chemical arguments for the origin of oil from living matter: The complex mix of compounds found in oil cannot have been formed simply by heating the carbon, hydrogen etc. together. Sunlight (photosynthesis) was necessary for their formation. Many component molecules of crude oil have backbones analogous to current plant substances (isoprenes).
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Pooh-Bah
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Damn, Werner, you just spoilt my holier-than-thou-ness this afternoon when I accidentally spilt a little oil while topping up my lawnmower. I thought, "Well, it's not a finite resource according to Prouty, so that's okay!"
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topping upI'd say "topping off". how's about anybody else?
formerly known as etaoin...
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how's about anybody else?
I don't have a lawn mower.
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Pooh-Bah
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Anybody says "topping off" to me and I assume it's another slang form for decapitation. And, Faldo, I sympathise, but first you gotta have your actual lawn, hmmm?
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I don't have a lawn mower.
you can borrow mine.
what about the gas tank of your car? do you top that off, or up?
and de-Cap, that would be "Lop off" to me...
formerly known as etaoin...
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addict
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I fill it up, but top it off. Same difference.
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I thought, "Well, it's not a finite resource according to Prouty, so that's okay!"And, according to Prouty, Churchill poisoned FDR!  So, yeah, sure, then I guess anything's possible...limitless oil...why not? 
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old hand
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Top up for gas tanks and drinks (don't mix those up!). I only use top off as a figure of speech when something goes horribly wrong after a day of horrible wrong-goings. "And then, to top it all off, I'm sitting here on hold checking the AWAD Board!!!!"
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Lawns are bad for the local eco-system [ducking].
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old hand
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Lawns are bad .. I agree - there are still far too many lawn-abiding citizens
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Here's how one online geologist responded to my question about the pre-Isuan sequence:
"I'm not really sure. I think most of the Hadean/Priscoan epoches are actually modelled on (and named after) lunar geology"
Onward.
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In reply to:
lunar geology
luneology? selenology?
Bingley
Bingley
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luneology? selenology?
looneyology? craterology? greencheeseiology?
And if we find fossils on the moon:
palaeolunarontology?
and if we find oil on the moon:
lunarcrudeology? (or, Boom goes the Moon!)
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palaeolunarontology?
As opposed to palæogeontology?
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