Posted on 07/10/2004 8:00:26 PM PDT by bondserv
The basic divisions of Earth’s internal structure (crust, mantle and core) have been known for a long time. But the evolutionary path that gave us this structure, and that provides the dynamics of plate tectonics, volcanism and magnetic-field generation, remains poorly understood. Why do we have plate tectonics? What is the nature and extent of melting deep within Earth? How does the core manage to keep generating such a richly complex magnetic field?
Stevenson is on my team!
Not according to the articles you referenced. Both affirm plate tectonics and give elucidative explanations.
Meaning that you intend not to see, and to continue to misrepresent based upon your carefully filtered ignorance.
What has been explained to you is based upon adequate information already. Plate tectonics is not going to vanish. It already works better than the ignorance we had before. It explained the previously apparent fact that the continents have drifted. (Wegener had noticed this decades before PT was proposed, but couldn't explain how it had happened.)
It should (but doesn't) tell you something that Coppedge has to dig his foaming-at-the-mouth naysayer out of the dust of 32 years ago, when PT was in its infancy. The guy was wrong, and he's nobody now except to you and Coppedge.
An enumeration of remaining issues is not an attack on the model that has provided all the answers so far. Your statements are false. Do you care? You are not a very good poster boy for the effects of faith in things unseen.
(For background, see 04/02/2004 and 11/04/2003 headlines.)
Rare form!
Admit that you disagree with this; "We know surprisingly little, admits David Stevenson (geologist, Caltech)".
My only point!
The Downfall of Uniformitarianism 11/04/2003
Can major paradigm shifts occur in science today? Check this one out.
You’ve seen it on TV science programs and in textbooks: plumes of hot magma from deep in the Earth’s mantle rise through the crust and erupt on the surface (the IMAX movie Yellowstone has computer graphics of the whole process). Perhaps you’ve seen animations of the Hawaiian Islands riding over a “hot spot” and building its chain of volcanoes over millions of years on its slow, drifting journey. Textbook diagrams show cross-sections of Earth’s crust, with lava erupting from channels rooted deep in the mantle, while crustal plates float and drift atop deep convection currents.
That’s all defunct now, and so is a lot of the uniformitarian dogma associated with it, claims Warren B. Hamilton (Colorado School of Mines), in an extensive article in this month’s GSA Today.1 Uniformitarianism is out, catastrophism is in. Now, don’t get the idea Hamilton denies the Earth is billions of years old; he still accepts the 4.567 billion year figure, the condensation of Earth from a solar nebula, and all that. But he replaces Charles Lyell’s old premise “the present is the key to the past” with a new picture that seems to pay homage to Stephen Jay Gould. He calls his model “Punctuated Gradualism.” How serious is the subject? Enough for him to entitle his paper, “An Alternative Earth,” and for it to get prominent press in a journal of the world’s leading geological society.
Here’s the overview Hamilton provides of his paradigm, and the timeline of catastrophic events he now envisions (Note: Ga = giga-annum, i.e., a billion years. Emphasis added in all quotes):
The Earth described here differs profoundly from that accepted as dogma in most textbooks and research papers. Crust and upper mantle have formed a mostly closed system throughout geologic time, and their dramatic temporal changes are responses to cooling. The changing processes define a Punctuated Gradualism and not Uniformitarianism. Major stages in Earth evolution:While much of this timeline looks standard, some of the underlying changes to assumptions are striking. The rhetoric is also notable in that the new view is revolutionary, and overthrows long-held beliefs about uniformitarianism and plate tectonics. Notice his confidence in the abstract: “Plumes from deep mantle, subduction into deep mantle, and bottom-up convective drive do not exist.” In his Overview, he outlines how the old ideas have died:
- 4.567–ca. 4.4 Ga. Hot accretion and major irreversible mantle fractionation. Giant bolides continue to ca. 3.9 Ga.
- 4.4–3.5 Ga. Era of nearly global felsic crust, too hot and mobile to stand as continents.
- 3.5–2.0 Ga. Granite-and-greenstone era. Permanent hydrosphere. Old crust cooled to density permitting mafic melts to reach surface. Diapiric batholiths mobilized from underlying old crust.
- 2.0 Ga–continuing. Plate tectonic era. Distinct continents and oceans. Top-down cooling of oceanic lithosphere enables subduction that drives plates, forces spreading, and mixes continental as well as oceanic crust into upper mantle.
The conventional model (e.g., Turcotte and Schubert, 2002) of Earth’s evolution and dynamics postulates that most of the mantle is little fractionated, major differentiation continues, and continental crust has grown progressively throughout geologic time; through-the-mantle convection operates, lithosphere plates are moved by bottom-driven currents, and plumes rise from basal mantle to surface; and plate tectonics operated in early Precambrian time. All of these conjectures likely are false. They descend from speculation by Urey (1951) and other pioneers, reasonable then but not now, that Earth accreted slowly and at low temperature from fertile chondritic and carbonaceous-chondritic materials, heated gradually by radioactive decay and core segregation, and is still fractionating.Hamilton explains that “The notion of a cold, volatile-rich, young planet has long since been disproved,” but its corollary of an unfractionated [i.e., homogeneous, and therefore fluid] lower mantle no longer can stand up to the facts; “major constraints” now rule this view out in favor of shallow crustal activity from the upper mantle and crust. This includes radioactive heating, of which he says, “Earth’s heat loss, now largely of radiogenic heat, is much overstated in the standard model.” He suggests a value 70% the earlier one, and states, “thermodynamic and mineral-physics data require that nearly all radioactivity be above 660 km (Hofmeister and Criss, 2003),” i.e., no deeper than 400 miles. At that depth there is a discontinuity that could not be breached by a magma plume.
Many published models are misleading: colors are saturated for lower-mantle anomalies one-tenth or one-fifth the amplitude of upper-mantle ones, huge unsampled volumes are assigned average values or populated with spherical-harmonic artifacts, illusory continuity is generated by severe smoothing and sharpening, cross sections are placed where subduction interpretations look most plausible. Models account for only a few tenths of traveltime variance, and have not been tested by attempting to squeeze solutions back into upper mantle. Nonsubduction alternatives receive little evaluation.
What’s most interesting about this story is not the new model, which may become the next discarded paradigm in the future, but the frank and revealing charges made against proponents of the old model: that they cheated, lied, and used irrational arguments to prop up their beliefs. Is that possible in science? You read it right here.
Creationists have similarly argued against the standard model for a long time and maybe now are getting some comeuppance. Dr. Walter Brown, for instance, has complained that deep mantle magma plumes are impossible, because the kinematics and thermodynamics would force the channels shut (see his paragraph on volcanoes and lava). Volcanism, therefore, must occur at shallow depths.
What can we learn from this paradigm shift? Make no mistake: confident-sounding scientific models, replete with professional jargon, (maybe even this one here - cf. 11/14/2002 headline), are written by fallible human beings. Like a hollow idol on a pedestal, a popular theory about the unobservable past might gleam in the sun for awhile, till toppled by tremors of fact. Broken on the ground, it is swept away and forgotten, and then a new hollow idol takes its place. Why hollow? Because no observer was there to corroborate the processes or the vast periods of time they are assumed to take. Remember Grand Canyon! It was the prototypical case of a phenomenon requiring millions of years, yet now the consensus is growing that it was formed catastrophically and recently (see ). It should seem foolish to place one’s faith in the conjectures of mortals instead of in the testimony of an authoritative Eyewitness.
Those not beholden to secular geological conjectures might well consider what this paradigm shift may do to other geological conjectures. It may well cause a domino effect on current models in subjects as diverse as radiometric dating (which assumes pristine, unprocessed material from the deep mantle), planetary differentiation, seismology, volcanology, magnetic field dynamo theory, and even the origin of life. This model tinkers with temperatures, chemistry, the nature of the core and mantle, the timing of continents, and a host of geophysical processes affecting land and sea. Evolutionists had better revisit their assumptions about the early earth and what this does to their beliefs.
Now that mantle plumes and deep plate tectonics are out, who knows what will happen next? Perhaps Hamilton’s shallow plate tectonics theory will topple for other reasons. It seems to hinder large migrations of plates, such as the belief that India migrated from lower Africa, crashed into Asia and built the Himalayas. His choice of terms, “punctuated gradualism,” recalls Stephen Jay Gould’s punctuated equilibria, the “Alternative Earth” model in biology. It arose out of frustration with the lack of evidence for Darwinian gradualism, not because of positive evidence for the alternative. Gould replaced that “standard model” (neo-Darwinism) with – what? – a new model with even less empirical support, claiming, essentially, that evolution happens so fast it leaves no trace in the fossil record! Is Hamilton’s “Punctuated gradualism” a parallel in geology? It seems, at least, to nail the coffin shut on Lyell’s principle of uniformitarianism. Whatever happens next, we have just seen that major paradigm shifts are still possible in science. Kuhnians rejoice. Darwinians beware.
Also found in the article this thread is regarding.
You need to tell your boys to keep it down.
“Mobile magma plumes force us to reassess some of our most basic assumptions about the way the mantle operates,” says John Tarduno, professor of earth and environmental sciences at the University. “We’ve relied on them for a long time as unwavering markers, but now we’ll have to redefine our understanding of global geography.”(Emphasis added.) The original paper is published in Science Aug. 21. [exerpt]
Bump to read discussion later.
Your only point is Coppedge's only point. (You drag everything he ever does here to FR.) His only point is that if you keep meticulous track of all the unexpected results, minor revisions, areas of controversy, recitations of questions not yet answered, and anything else that can be spun as a sour note, perhaps you can rope a few dummies into thinking that science doesn't know anything and it's all a house of cards.
Maybe you can even get someone to echo that your funny collection of quotes and snippets is an "alternative theory" that needs "a place at the table" in the schools. Maybe. There's one born every minute.
Admit that you disagree with this; "We know surprisingly little, admits David Stevenson (geologist, Caltech)".
He is emphasizing the still-unknown, which he earlier enumerated. You are pretending that what is known is not, that in fact nothing is known and that everything is likely to go away next month, per the ranting of Mr. 1972. This is wrong. There is no telling to what exact degree Coppedge is a liar and to what degree a nutcase blinded by Morton's Demon and incapable of responsiblity for his actions. It can safely be said that to whatever extent it isn't one it's the other, however. Same with you.
You need to tell your fellow young-Earth data lawyer that every source he has cited (with the possible exception of Mr. 1972) accepts that the Earth is billions of years old, that the fission of radioisotopes heats the core, that continents ride the mantle like the scum on hot cocoa, that plates spread from mid-ocean ridges, etc. When one "model" versus another is argued in the recent literature, the comparison is not plate tectonics versus some 6-day supernatural fairy tale. All of the models are plate-tectonic models.
The Hawaiian Island chain is not the result of plates moving over a stationary hotspot, apparently (see also April 1 headline).The model of the formation of the Hawaiian chain has not that I have so far found been questioned, only the exact nature of what a hotspot is, how hot, and how formed. If one assumes that a "hotspot" is a volcanically active area (containing an upwelling of "melt"), then the model of the formation of the Hawiian chain remains one of dragging lithospheric plate over said hotspot. Coppedge either cannot read or cannot pass up the chance to creatively misread.
The person quoted below is; Warren B. Hamilton (Colorado School of Mines), in an extensive article in this month’s GSA Today.
No more mantle plumes allowed. Of the prototypical Hawaiian Islands case, he says, “There, in its only rigorously testable locale, the fixed-plume concept is falsified.” How do supporters typically respond? He claims, “Plume advocates respond to such refutations by making their conjectures ever more complex, unique to each example, and untestable.” Yet beyond this, “All other geochemical, kinematic, and tectonic plume rationales derive from the misinterpretation that Hawaii stands atop a plume.”
I told you what they are saying. You and Coppedge come into the picture because, almost every time, what they are saying isn't even what he and you are saying. And your idea of answering me is coming back dumb as a stump again...
And Again:
The mid ocean ridges. Magma flows from the core making new plate material. This builds up forming a ridge associated with an expansion zone. Gravity Pulls down on the pile of rock, all the while magma is flowing on top. The ridge spreads, putting the rest of the plate into compression. The energy is coming from the earths core.
Don't get me wrong, much of what you say is an accurate representation of the plurality of thought in Geology. I understand that completely, and have never denied it. There is much yet to understand, and many current models are subject to drastic change.
Knowledge is a poor substitute for a relationship with the Creator. The hole in our life that we try to fill with understanding what is around us, would be better spent being filled by the One who made what is around us. After all, by definition, God can wipe the slate and change the knowable into something completely opposite.
The sinless Jesus Christ died on the cross in order for us to have access to that which we forfeited through our transgressions. We are a mimic of the Creator who made us as we try to create a world in which we would like to live. When we have humbled ourselves enough to play using His rules, and His wisdom and energy, we can have eternal life starting today. Ask Jesus Christ to be your savior, and watch the important things of this world melt away, and become the spiritual building of Godly character in your life.
Those were the good old days. ;-)
What has RWP been up to of late. He's not spending much time FReeping these days.
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