The Geologists Were Wrong

More examples of collapsing theories have appeared in the literature this week (compare last week, 01/21/2008):

1. Dirty Comet:  The Stardust spacecraft that collected comet samples in 2006 was so named because it was believed comets contained pristine material from the birth of the sun.  That has all changed.  National Geographic News summarized a paper in Science¹ that expressed a real surprise: Comet Wild 2 was as dirty as an asteroid, and had earth-like composition.  “The first surprise was that we found inner solar system materials, and the second surprise was that we didn’t find outer solar system materials,” remarked one researcher.  Richard Kerr, writing in Science,² said they didn’t even find one speck of unaltered, presolar material.
       But then, how could this comet retain volatile gases at all if it spent much time close to the sun?  “It’s coming apart like crazy at its present distance,” said principle investigator Donald Brownlee.  And where are the pristine remnants of the early solar nebula – if they exist at all?  The entire field of comet studies is up in the air.  “For those of us who study presolar materials, it’s turned out to be a bit of a bust,” said a team member.  “It’s changing the way we think about comets.”  See also PhysOrg, which quoted a researcher saying, “I think this is science in action.  It’s really exciting because it’s just not what we expected.”  If science is constantly being surprised by the unexpected, to what degree can scientists claim they are making progress?
2. Farewell to Mantle Plumes:  The textbook case of a mantle plume is the Hawaiian Island chain.  According to theory, it floats over a “hot spot” in the crust where deep mantle material is rising.  The evidence on which this has been based, isotopic signatures of osmium and other elements, is now found to be flawed.  According to a paper in Science,³ the signatures are too heterogeneous to constrain the theory.  All the isotopic signatures could be accounted for by processes occurring in the upper mantle, not deep mantle plumes.
       Anders Meiborn, in the same issue of Science,⁴ called it the “rise and fall of a great idea.”  He listed four major observational inconsistencies with the long-held belief.
       The finding also affects theories about undersea lava.  “The concept of isotopic ‘anomalies’ in oceanic basalts thus has to be applied with extreme care,”he warned.  “Indeed, with an upper mantle as heterogeneous as the data by Luguet et al. suggest, it is difficult to imagine that isotopic signatures in oceanic basalts can be uniquely tied to the outer core.”

In addition, Science contained an entertaining article by Richard Kerr about the geologic time scale.⁵  Ever hear of the Quaternary period?  The name is in the midst of a tug-of-war between geologists who want to keep the name on the charts, and those who want to scrap it in favor of Lyell’s term Pleistocene.  Some are surreptitiously sneaking the name out in their books and charts, but others who like the old name aren’t about to let them get away with it.
    Changing the time scale means adjusting other names, cutting and pasting, and moving periods around.  Old books and charts risk going obsolete.  This is too upsetting for some geologists.  Some want a battle, some want compromise.  The article reads like a day at the academic wrestling ring.  Sample:

Some geologists are incensed.  “All of a sudden they want to move [the Pleistocene] down 800,000 years,” says marine geologist Lucy E. Edwards of the U.S. Geological Survey in Reston, Virginia.  “Why?  ‘Because we want it.’  It upsets the stability of the nomenclature without a good scientific reason.  Many more marine geologists working in the Pleistocene would be completely discombobulated.”

If the name Quaternary disappears from the books, did it ever exist in the rocks?  That’s a debate for humans.  They are the ones who have a penchant for classifying things.

1.  Ishii et al, “Comparison of Comet 81P/Wild 2 Dust with Interplanetary Dust from Comets,” Science, 25 January 2008: Vol. 319. no. 5862, pp. 447-450, DOI: 10.1126/science.1150683.
2.  Richard A. Kerr, “Where Has all the Stardust Gone?”, Science, 25 January 2008: Vol. 319. no. 5862, p. 401, DOI: 10.1126/science.319.5862.401a.
3.  Luguet et al, “Enriched Pt-Re-Os Isotope Systematics in Plume Lavas Explained by Metasomatic Sulfides,” Science, 25 January 2008: Vol. 319. no. 5862, pp. 453-456, DOI: 10.1126/science.1149868.
4.  Anders Meiborn, “The Rise and Fall of a Great Idea,” Science, 25 January 2008: Vol. 319. no. 5862, pp. 418-419, DOI: 10.1126/science.1153710.
5.  Richard A. Kerr, “A Time War Over the Period We Live In,” Science, 25 January 2008: Vol. 319. no. 5862, pp. 402-403, DOI: 10.1126/science.319.5862.402.

We must constantly be reminded of the difference between brute facts and the fallible names and explanations humans impose on them.  What if the whole schemes about the earth’s core, the evolution of the solar system, and the geologic time scale were wrong?  Would it be determined by the brute facts?  How would fallible humans know?  The earth is the same, and the comet is the same, but human concepts have undergone multiple revolutions in the last few centuries.
    Sometimes the very names we impose on things drive our conceptions of what they are.  Truths of reality are not obligated by human nomenclature, group consensus or majority vote.  Paradigm shifts may be more indications of erratic movement, not progress toward The Truth.