Jul
21

Nature’s Calendars, Part 1: Ice Cores and Sediments

I didn’t post one in June, but this week I’d like to continue my series of excerpts from Hugh Ross’s book A Matter of Days, 2nd ed., about scientific measurements for distance and, especially, time (e.g., the age of the Earth and certain things on it). Whereas in May we looked at radiometric dating, this time we’ll consider dating via ice cores and sediments.

Dr. Ross…

“Tree rings, coral reefs, ice deposits in Antarctica and Greenland, and sedimentary layers in lakes and seas are like calendars in that they record the passing of years. Each year another layer is added. By counting the rings or layers, an investigator can determine for how many years the tree, reef, ice deposit, or sediment has been in existence.

These rings and layers cover different time periods but overlap considerably. The overlap is sufficient to connect the present to the past in a complete and continuous manner over the past several million years. The sequence of layers and rings confirms the constancy of the radiometric decay rates and the reliability of radiometric dating in the following ways.

Three ice cores from Antarctica — Dome C, Dome F, and Vostok — provide a continuous record of the past 800,000, 720,000, and 420,000 years, respectively. Two ice cores in Northern Greenland, NEEM and NGRIP, and two ice cores in central Greenland, GRIP and GISP2, yield a continuous record of the past 135,000, 123,000, 105,000, and 105,000 years, respectively.

The annual layers of the ice cores contain radiometric isotopes. Analysis of those isotopes established that radiometric decay constants indeed did not vary at any time throughout the past 800,000 years. Also, the layers demonstrated that Antarctica and Greenland were not, within the past 800,000 years, inundated by a massive flood.

Article by Carl Wieland in *Creation* magazine

For most scientists and laypeople such compelling and straightforwardly simple evidence confirms that Earth is more than a few tens of thousands of years old. Young-earth creation scientists, however, insist that geophysicists are wrong in presuming that the core layers are annual deposits. They claim that all, or virtually all, the ice residing over Antarctica and Greenland was laid down after the flood of Noah’s time and that only one major ice age has ever occurred. As ‘proof,’ they cite the ice burial of World War II fighter planes in Greenland to a depth of 250 feet in only fifty years.

According to these individuals, layers in the ice cores represent multiple meltings and freezings that occur throughout a single year. Thus, rather than 10,000 layers testifying of the passage of 10,000 years, they might instead attest to the passing of only a hundred or ten years or even less.

Their claim has some validity for the fighter planes buried in ice in southern Greenland. Southern Greenland does have multiple melt and freezing episodes within a single year. For this reason the ice cores mentioned above were all drilled in high altitude areas of central Antarctica and northern and central Greenland, hundreds of miles from the nearest sea coasts. There, multiple melt and freezing episodes do not occur.

Additional evidence that the ice core layers really are annual events arises from three sources. First, embedded within the layers are dust signatures of known volcanic eruptions. For example, we know the Krakatoa eruption took place in 1883, and the Vesuvius eruptions occurred in AD 79, 472, 512, 968, 1037, 1139, 1631, and 1944. Counting the layers between layers that contain the dust signatures of these eruption events, researchers have confirmed that each layer indeed corresponds to one year.

Second, variation in the eccentricity (a measure of the noncircularity) of Earth’s orbit about the Sun is clearly seen in the Antarctica ice cores. Seasonal changes affect layer thickness. As Earth’s eccentricity increases, the seasonal changes increase in direct proportion. Earth’s eccentricity changes are driven primarily by Earth’s interactions with the gravitational fields of Jupiter and Saturn. Those interactions generate a 100,000-year periodic cycle in the eccentricity of Earth’s orbit, and that cycle is clearly visible in the thickness variations.

The 800,000 Dome C ice core layers show eight complete cycles of variation in Earth’s eccentricity. The Dome F and Vostok ice cores show seven and four complete cycles, respectively. Thus, the law of gravity dictates that the Antarctica ice core layers are annually deposited layers, that Earth is at least 800,000 years old, and that radiometric dating yields reliable dates throughout the past 800,000 years.

Third, a marine sediment core off the coast of South Island, New Zealand, reveals southern hemisphere climate changes throughout the past 3.9 million years. The sediment layers in this core show the same cycles in the periodic variation of Earth’s eccentricity as do the three deep Antarctic ice cores, thereby confirming that the three ice cores really do provide a faithful record to the past 800,000 years of Earth’s history. Conversely, the Antarctic ice cores indicate that the New Zealand sediment core can be trusted in showing that Earth is at least 3.9 million years old and that radiometric dating provides trustworthy dates throughout the past 3.9 million years.”