Stuff Geologists Think They Know Till Tomorrow
The science of geology is like quicksand, ever shifting and not rock solid.
Mars water proved! On second thought… (PhysOrg): It was just a few months ago that planetary scientists announced the “strongest evidence yet” for liquid water on Mars. It was inferred from gullies on crater walls, prompting some to propose missions to search for life there. Now, two scientists publishing in Nature Geoscience say there is probably no water in the gullies. Instead, the BBC News suggests, the gullies are formed from the escape of trapped carbon dioxide.
Age of Martian clays cut in half (Science Daily): It’s 3.7 billion years old. No, it’s less than 2 billion years old—Martian clay, that is. Hydrated minerals assumed to date from the hypothetical “Noachian” period have been reinterpreted because of presence in young craters. A billion here, a few billion there; what’s that among friends?
Earth rotation and sea level rise (Science Advances): “In 2002, Munk defined an important enigma of 20th century global mean sea-level (GMSL) rise that has yet to be resolved,” this paper begins. By tweaking various unobservables like “angular momentum exchange between the fluid outer core and the mantle,” the geologists got the observations to reconcile with one another, assuming a fake earth instead of the real one: “We assumed a spherically symmetric, self-gravitating, and Maxwell viscoelastic Earth model that is elastically compressible.”
Darwinian geophysics (Icarus): Did you know Darwin’s son Sir George H. Darwin was a prominent astronomer and mathematician? He proposed a theory of “Laplace planes” to account for Earth’s obliquity changes over time. Now, a NASA geodynamics scientist is saying it’s not so simple putting this puzzle together. “The equations do not allow the Moon to evolve out of its Laplace plane by tidal friction alone, so that if it was originally in its Laplace plane, the tilt arose with the addition of other mechanisms, such as resonance passages.”
Alaska, we have a problem (Science Daily): The title of this article is eye-catching: “Climate can grind mountains faster than they can be rebuilt.” Obvious question: if the Earth is billions of years old, why do we have mountains today? Scientists studying Alaskan sediments found a puzzle: “It turned out most [sediments] were younger than we anticipated, and most rates (of sediment production and thus erosion) were higher than we anticipated…. In fact, there was more erosion than tectonics has replaced.” Instead of abandoning their old-Earth assumptions, they accentuated the positive and eliminated the negative: “We were pleasantly surprised by how well we could establish ages” as they drilled, one said. But the article offered no solution to the conundrum. “Since the mid-Pleistocene, erosion rates have continued to beat tectonic inputs by 50 to 80 percent, demonstrating that climatic processes, such as the movement of glaciers, can outstrip mountain building over a span of a million years.”
Magnetic mystery of Earth’s early core explained (Nature): A colorful picture of Earth opened up like a pineapple begins this positivistic account of explanations for another enigma.
Geophysicists call it the new core paradox: They can’t quite explain how the ancient Earth could have sustained a magnetic field billions of years ago, as it was cooling from its fiery birth.
Now, two scientists have proposed two different ways to solve the paradox. Each relies on minerals crystallizing out of the molten Earth, a process that would have generated a magnetic field by churning the young planet’s core. The difference between the two explanations comes in which particular mineral does the crystallizing.
The “core paradox” is as young as 2012. Secular geophysicists who believe the Earth is billions of years of old have long had a physics problem on their hands: generating the Earth’s magnetic field. The consensus view invokes some sort of geodynamo created by flowing currents in the Earth’s molten core, but how was it sustained for billions of years when the Earth was young? “We need a dynamo more or less continuously,” one worried scientist says. One of the competitors says off his Japanese rival, “[Kei] Hirose is telling you something that can happen, not what did happen.” But would Hirose return that volley? Or would a third party use that criticism against them both? A proposal that might work is not a demonstration that it does work.
More importantly, both proposals ignore the observed 130-year downward trend of Earth’s magnetic field strength that implies it was much stronger in the past. Given the half-life decay curve, extrapolating it backward would make it unsustainably strong for even a few tens of thousands of years. Space.com briefly mentions this problem, saying that “its overall strength has been steadily decreasing relatively recently,” but geophysicist Paul Sutter immediately leaps to the dynamo theory for the rescue. Nevertheless, his opening paragraph about Earth’s uniqueness bears pondering:
Earth has a force field. A real, literal, honest-to-goodness force field. A field that projects invisibly out into space, protecting us and our precious atmosphere from the dangers of the cosmos. Without it, we might just have ended up like Mars: a wasteland, a failed chance at life.
Age of this cave is a fact, except for the mismatch (PhysOrg): Scientists are claiming a “complete and very precise” climate record for 500,000 years, based on limestone deposits in Devil’s Hole, a water-filled cave in Nevada. But there’s a “big mystery” yanking their confidence back: “Existing palaeoclimatological data from Nevada do not tally with data obtained elsewhere, for instance, from seabed deposits,” the reader finds at the end of the article. “This fact is still the subject of controversial discussions within the scientific community and an unresolved issue in climate research.” Update 1/07/16: A paper in Science Magazine claims to reconcile the dates with new measurements from another cave, Devil’s Hole 2. As with any dating method, assumptions are made about the interpretation of markers such as isotopes, and some values are averaged.
East Antarctic Ice Sheet has stayed frozen for 14 million years (PhysOrg): The previous entry should create caution when evaluating this overconfident claim. Jane Willenbring used beryllium ions to arrive at a date for the Antarctic ice sheet, claiming that “This means that the sediment is definitely older than the time when a lot of people think that Antarctica might have been quite deglaciated.” Well, were the scientists who thought that wrong? Her claim of long-term stability is running afoul of climate change scientists who want to scare the public that the ice sheets are in danger of imminent collapse. She gives them an escape route; “Willenbring, however, cautions that even though carbon dioxide levels in the Pliocene may be analogous to today’s levels, the two situations are not equivalent and thus any conclusions can only be taken so far.” For practice, try evaluating this PNAS claim: “Continuous 1.3-million-year record of East African hydroclimate, and implications for patterns of evolution and biodiversity.”
If you trust what a geologist says today, you’ll have to shift your trust to another one tomorrow who says something different. Being completely wedded to Lyell’s uniformitarianism and to Darwin’s need for millions of years of evolution, secular geologists are in a perpetual state of tension between observations and long-age dogma. They don’t seem to mind as long as they can stay employed. It lets them go on field trips, where they can scrape thin limestone flakes on the walls of caves and make global pronouncements from them. It lets them go to scientific conferences and argue with each other while sipping lattes and gulping dainty desserts. If we counted the number of times geologists have changed their minds on things over the last 15 years of CEH reporting, sensible readers would have strong reasons to doubt that they understand the real world. They will admit to controversies, but the controversies exist between imaginary worlds of their own making.