Posted by jlwile on June 28, 2009
In the previous entries on this subject, I talked about the earth’s magnetic field and dendrochronology as evidence that the earth is on the order of 10,000 years old. I want to continue this discourse now with one of the most well-studied processes used to estimate the age of the earth: the amount of salt in the oceans.
Everyone knows that the water in the oceans is salty. In fact, the average sample of seawater is 2.7% table salt (sodium chloride). To a chemist, the term “salt” includes a lot more than just table salt – it includes any ionic compound. If I include all things that chemist classify as salts, the average sample of seawater is 3.5% salts. It turns out that the amount of salt in the oceans has been studied for almost 300 years1, so we know a lot more about it than most of the other processes used to estimate the age of the earth. What we know indicates that the earth is young.
Since the term “salt” is a broad one, the typical analysis of salt in the oceans is focused on one ion: sodium (Na+). It is the most prominent positive ion in seawater, so it is a reasonable one to study. Over the years, scientists have studied the many ways that sodium enters the oceans. For example, rivers pick up sodium as they erode rocks and sediments, and they end up dumping that sodium into the seas. Glaciers, hydrothermal vents, groundwater, surface runoff, atmospheric dust, and volcanic emissions also put sodium in the oceans. Austin and Humphreys summed up the best measurements of these processes in the scientific literature and concluded that the average amount of sodium being put into the oceans via natural processes is 457 million tons per year. 2
Now the oceans also can get rid of sodium by several natural processes. When the surf sprays water on the land, some of the sodium goes with it. In addition, some substances in the oceans (like clays and zeolites) absorb sodium. So while the oceans gain sodium every year, they also lose it. Austin and Humphreys added up the best measurements of the rate at which the oceans lose sodium by these processes, and they found that the oceans lose sodium at a rate of 122 million tons per year. 2
So what does this tell us? The oceans are getting saltier over time. In fact, they are gaining sodium at a net rate of 457-122 = 335 million tons each year. Well, if these rates have remained relatively consistent over time, it gives us an idea of how old the oceans could be. After all, suppose the oceans started with no salt at all and started gaining sodium at a rate of 457 million tons each year. At first, it would lose no sodium (because the rate at which sodium loss happens depends on the amount of sodium in the oceans), but as time went on, the sodium removal processes would ramp up, and after a while, they would be losing sodium at a rate of 122 million tons per year. Under that scenario, how long would it take to reach the level we measure today? The answer is 32 million years.
Now you might wonder whether or not we really know how much sodium is entering the oceans and how much is leaving the oceans. After all, the oceans are really big. Do we truly know all the ways sodium can enter and leave the oceans? I don’t know. However, I can tell you this: We have been studying this specific question for 300 years. That’s about THREE TIMES longer than we have been studying radioactivity, which is one of the main processes that causes scientists to think the earth is billions of years old. Thus, we understand this process much better than we understand radioactivity.
We even have estimates for the error associated with the measurements of how much sodium the oceans are gaining and losing. These error estimates essentially tell us how much lower or higher the actual rate might be from the measured rate. So…if we want to “squeeze” as much time as possible out the data, what can we do? We can assume that our measurements for sodium intake are all too large. After all, if sodium intake rates are lower than the measured value, it would take longer to fill up the oceans with sodium. Also, we can assume our rates for the oceans losing sodium are all too low. If the oceans can get rid of sodium faster than we think, it would also take longer to fill up the oceans with sodium.
Well, assuming that all the sodium intake measurements were made on the high side, we can use the error estimates to tell us what the minimum sodium intake rate would be: 356 million tons per year. Assuming that all the sodium loss measurements were too low, we can use the error estimates to tell us that the maximum rate at which sodium leaves the oceans is 206 million tons per year. This ends up telling us that the slowest possible current rate for the oceans gaining sodium is 150 million tons per year. So…the oldest the oceans could possibly be would be the time it would take to go from freshwater oceans to the current levels of sodium given the minimum rate of sodium increase (356 million tons per year) and the maximum rate of sodium loss (initially zero but ramping up to 206 million tons per year over time). At that rate, it would take 62 million years.
So we see that even with the most generous use of error estimates, the oceans simply cannot be even a hundred million years old, much less billions of years old. In fact, it is silly to think that the oceans were made of freshwater to begin with. After all, most of the organisms in the oceans depend on the salt levels of the oceans. It is most reasonable to assume, therefore, that the oceans have always been fairly salty. Thus, from a scientific point of view, it is most reasonable to assume that the oceans are SIGNIFICANTLY younger than 62 million years old.
So the data are quite clear. After 300 years of studying this issue, there is no way to understand how the oceans could have the levels of sodium we see today unless it is SIGNIFICANTLY YOUNGER THAN 62 MILLION YEARS OLD. In fact, given the kinds of life you find in the oceans, it is most reasonable to assume that the oceans are quite young, on the order of thousands of years old, as indicated by both the earth’s magnetic field and dendrochronology.
1. Halley, E., “A short account of the cause of the saltness of the ocean, and of the several lakes that emit no rivers; with a proposal, by help thereof, to discover the age of the world,” Phil. Trans. Royal Soc. 29:296-300, 1715.
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2. Austin, S.A. and Humphreys, D. R., The Sea’s Missing Salt: A Dilemma for Evolutionists, Proceedings of the Second International Conference on Creationism, 2:17-33, 1990.
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