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Thursday, June 12, 2014

"Best evidences for a young Earth": Snelling and our salty seas, Part 1

Is our universe is full of clues that it cannot be millions—let alone billions—of years old?

Many young-Earth creationists are convinced this is the case, despite that no scientists are scrambling to counter their claims. To understand why, I want to continue my review of Dr. Andrew Snelling's 10 Best Evidences from Science that Confirm a Young Earth, which attempts to equip readers with a set of foolproof arguments in favor of that position. Most recently, I examined Snelling's claim that given the modern ocean-sediment flux, our oceans cannot be more than 12 million years. It took little effort to expose the misleading tactics of Dr. Snelling, however, who miscited key papers and ignored some basic geological principles and data to build his argument. In the end, we find that the ocean-sediment flux offers no challenge to those who accept the conventional age of the Earth and its oceans.

Dr. Snelling and others have employed similarly deceptive methods to claim that our oceans should be much saltier, if indeed they are ~3 billion years old. According to Evidence #9, Very Little Salt in the Sea, more salt enters the ocean every year than is removed by natural processes. Dividing the total salt content of the oceans by the net rate at which salt accumulates yields a maximum age of 62 million years.

Figure 1 from Snelling (2012), illustrating basic inputs and outputs of Na
to the modern oceans. He cites a maximum age of 42 million years, rather
than 62 million years estimated by Austin and Humphreys (1990), whom
he cites (perhaps a typo?).

History of the 'Salt Chronometer'

Dr. Snelling is following in the footsteps of Edmund Haley (1715) and Irish physicist John Joly (1899), who first proposed quantitative methods by which the maximum age of the Earth could be calculated from the ocean's salt content (Hay et al., 2006). The latter concluded that assuming a constant influx of salt, no more than 100 million years could have transpired since the birth of originally freshwater oceans. Despite the ingenuity of these early calculations, geologists abandoned the salt chronometer in favor of radiometric dating for one vital reason. Geological history far too dynamic to assume constant geochemical fluxes (whether of salt or anything else), so the upper limits by Haley and Joly became scientifically meaningless. In addition, the discovery of relatively pure, sedimentary salt deposits indicated that salt can and has been removed from the oceans in the past, negating the principle claim by Joly that salt accumulation is an irreversible process.

Decades later, David Livingstone (1963) would revisit this question in terms of the sodium cycle. He confirmed that a net influx of sodium to the oceans did exist, following estimates of riverine delivery by Clarke (1924), by which all dissolved sodium could be accounted for in a few hundred million years. Livingstone (1963) recognized, however, that this upper limit is very sensitive to the estimated volumes of metamorphosed versus un-metamorphosed rocks, since the latter contain more sodium. After correcting the ratio, he concluded that the maximum age of the oceans (based on sodium cycling) could be extended to as many as ~2.5 billion years.

Young-Earth researchers Steven Austin and Russell Humphreys apparently were not satisfied with the work by Livingstone, so they devised their own assessment of the sodium cycle and its implications for the maximum age of the oceans. They presented their full-length paper in 1990 at the Second International Conference on Creationism, and it is this work primarily on which Dr. Snelling bases his claim that the modern oceans contain too little sodium for an old Earth.

Sodium, not salt

Sea salt consists of more ions than just sodium (Na+), so it should be noted up front that the titles of these YEC works are a bit misleading. The claim by Snelling, Austin, and Humphreys is not that the oceans are missing 'salt', but rather that if the modern, net flux of sodium (as calculated by Austin and Humphreys, 1990) is extrapolated blindly into the past, we arrive at a zero concentration of sodium about 62 million years ago. As with Snelling's examination of the ocean-sediment flux, this methodology is extremely simplistic and involves more assumptions even than the pioneering efforts by Halley and Joly. Hence, it should be obvious why geologists and geochemists are not scrambling to account for the ocean's missing salt: it's not missing.

So why focus on sodium, rather than other major components of sea salt: chlorine, calcium, magnesium, potassium, sulfate, or carbonate? The truth is, of these major ions cycling through the Earth's oceans and crust, we understand sodium rather poorly. Unlike the other elements, sodium does not have multiple stable isotopes, so it is far more difficult to track how it moves from crust to river to ocean to sediment and back again (stable-isotope ratios reflect how much of that element was added/subtracted via specific processes). Another reason that Austin and Humphreys focused on sodium, if I may conjecture, is that sodium is the only element for which there appears to be a positive annual flux to the oceans. If they had chosen to estimate the minimum age of the oceans using chlorine, calcium, magnesium, sulfur, or carbon, they would have arrived at an age of infinity or beyond.

Why are the oceans salty at all?

Before jumping into the details, we should pose this very simple question to YEC's. In the context of an 'old Earth', it makes sense why the oceans contain various dissolved salts in the concentrations observed today: crustal minerals have been weathered and eroded over millions of years, delivering dissolved ions to the oceans via river systems. But why, in the YEC scenario, do the oceans contain massive quantities of salt in the first place? The only answer that may be given is that God simply created the oceans to be salty, with a chemical composition that only appears to have been reached via long, geological processes.

This ad hoc response is typical for the YEC-style, retrospective fitting of data: "God made the oceans salty because otherwise, we can't explain why they're salty". Of course, I will grant that in a divine, fiat creation of the oceans, salty oceans are a hypothetical possibility. But I want to highlight the arbitrary nature of the explanation, because this characteristic is anticipated neither by scripture nor theology. On the contrary, we might expect freshwater oceans from the image of God separating the 'waters above' (the source of rain/snow) from the 'waters below' (the oceans). Salty oceans are not necessary to maintain the abundance of life therein, but rather an impediment to many organisms sensitive to salinity changes. God may as well have made freshwater oceans with marine organisms suited to living in freshwater—why not? Instead, the undrinkable seawater makes the oceans a terrifying desert to humans, among other creatures.

In conclusion, one may speculate as to the divine reason behind the oceans being salty, but the argument will always proceed in the opposite direction of scientific inquiry. This one example elucidates how the YEC paradigm does not arise from scientists examining the same evidence through an alternative worldview. Conventional geologists form testable hypotheses against the evidence until a unifying theory emerges; YEC geologists shake the box of data until a few pieces seem to fit into their preconceived notion of Earth history. The very methodologies are antithetical, and so the resulting paradigms will never converge.

Unscientific procedures

With regard to both ocean sediments and dissolved sodium, YEC's have utilized overly simplistic models to estimate the maximum age of the oceans. It is vital to understand that their conclusions depend on the accuracy of a scientific model, because all models work on a suite of assumptions in an attempt to describe reality. Now, relying on assumptions does not cripple science. On the contrary, it is both necessary and productive, because identifying model assumptions opens them up to falsification, a key component of science. As the saying goes, 'all models are wrong, but some are useful'. We expect from the beginning that Austin and Humphreys' model will be wrong, but to what extent is it useful?

To determine this, Austin and Humphreys need to demonstrate that the intrinsic assumptions of their model are robust. For example, Austin and Humphreys assume that the mass of sodium delivered to the oceans by rivers remains constant over time (or at least within a narrow range). But is this a valid assumption? To my knowledge, neither author has established why the riverine input of sodium could not have varied more substantially in Earth history, though basic geology tells us that it should. The bottom line is, no serious geologist/geochemist attempts to reconstruct Earth history by extrapolating modern rates blindly into the past, so the methodology of Snelling, Austin, and Humphreys is about ~200 years out of date. In my next post, therefore, I will examine the sodium inputs and outputs utilized by their model in light of modern geological principles and studies. How well do you suppose their numbers hold up?

A lot can happen in 24 years...

Since the original publication by Austin and Snelling (1990), little to no attempt has been made to update this common YEC argument for a young Earth. Nonetheless, real geological research has expanded exponentially on this topic, due to advances in technology for surveying the deep oceans. More data are available to estimate riverine inputs of salt and sediment. Major depositional and tectonic events have been discovered or better described, which should impact reconstructions of paleooceanographic conditions (like salinity, sediment recycling, etc.). One of the weaknesses of the YEC approach is that it too commonly relies on a select few papers while ignoring followup research. For example, this paper by Holland (2006) addressed the topic of seawater composition over the past ~550 million years. Was he scrambling to explain why the oceans are not saltier? On the contrary, he writes:
"The sum of the two loss rates [of sodium] is the same, within the uncertainty of the measurements, as the estimated rate of the river input of Na+." p. 231
In reference to the following table of modern and mid-Cenozoic fluxes:

From Holland (2006); summary of Na inputs and outputs to/from the oceans.
I would anticipate YEC's to respond that this approach is too simple (Austin and Humphreys do include more inputs and outputs), but we'll find out in next post why it is not. In any case, we should note that Snelling, writing in 2012, ignored and dismissed the ongoing research since 1990, such as by Holland (2006). For this reason, authors like Snelling may persuade their own audience of YEC readers, but will never impact the scientific community.

(to be continued...)


Additional Reading (from The Natural Historian Blog):

The Salty Sea and the Age of the Earth, Part I – Confirmation Bias
The Salty Sea Part II:  A Young Earth Salt Chronometer?
The Salty Sea Part III: Are the Oceans Getting Saltier Over Time?

1 comment:

  1. Life must be simpler for creationists who are prepared to accept billions/millions of years ...

    I see that YECs are claiming Bill Nye got something wrong at the Ham debate:
    http://www.piltdownsuperman.com/2014/06/fossils-in-wrong-place-thwart-evolution.html
    http://www.icr.org/article/8167/
    (they appear to be saying that 'living fossils' manage to 'thwart' evolution and evolutionary timescales - and simply point to a catastrophic recent flood ha ha)

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