How old is the Earth? Are young-earth arguments equal in rigor to those supporting an old Earth? How can we tell what happened in Earth history when no one was there to witness it? Exploring Earth history is more straightforward than many realize, with many ways of putting competing hypotheses to the test. This video-animation provides a great example from the Hawaiian Islands. It walks through a series of expectations for young- and old-earth models, taking into account expectations for volcanism, shifting tectonic plates, the degree of erosion, the size of reefs, and the distribution of reef species. Expectations fit quite well with only one model.
Note on 2018 Kilauea lava flows. Kilauea, on the Big Island of Hawaii, is one of the most active volcanoes in the world, with nearly continuous lava flows for over 30 years! It rarely makes the news unless lava threatens towns and roads. Beginning in May of 2018, new vents opened on the populated southeast side of the island, tragically destroying more than 650 homes and over 6000 acres of land. Kapoho Bay, where rivers of molten rock flowed into the ocean, is now filled with solidified lava. Why do eruptions only occur on the Big Island, and none of the others? The video tells the story.
The Hawaiian Islands offer a fascinating natural laboratory to test young earth and old earth models, including the reliability of radiometric dating. Both models have clear expectations that can be compared with what we actually find in nature.
The Hawaiian Islands and Emperor Seamounts formed as a result of the Earth’s crust moving over a semi-stationary hot spot deep in the Earth’s mantle. The hot spot heats and expands the crust, eventually melting conduits to the surface and building a volcano on the seafloor.
As the crust moves, the source of lava is cut off from the older volcano and a new one begins to form. Away from the hot spot, the crust shrinks, making the island sink – a process called subsidence. The islands also begin to erode, and reefs grow up around the edge, building up layers to stay where sunlight still reaches.
According to the old earth model, this process has been going on for a very long time, maybe sometimes slower or faster, but spread over many millions of years. According to the flood geology, or young earth model, these islands and seamounts all formed in just a few years, maybe in as little as a single year, after the start of Noah’s Flood.
These different models lead to very different expectations in terms of the degree of erosion from one island to the next, the degree of subsidence, reef thickness and fossils, and what should be expected when rocks from each island are radiometrically dated.
We’ll start with the flood geology model. Flood geologists argue that when Genesis says the “floodgates of the deep opened up” that this is a reference to the crust rupturing at the start of the flood and beginning to move tens of miles per hour. In this view, the hot spot began some time after the beginning of the flood, and was extremely active, bursting to the surface and forming one volcano after the other in rapid sequence.
With most of the islands formed at nearly the same time, the crust should have cooled at about the same rate, so each island should have experienced about the same amount of subsidence. Each island should also have experienced about the same amount of erosion and growth of reefs around the edges. And if we looked closely at the fossil reef organisms, we should find the same kinds on all the islands since they all were forming at about the same time in the ocean.
Now let’s consider the old earth model. Radiometric dating of rocks from many of these islands and seamounts indicate steadily increasing ages up to about 80 million years.
Islands formed over millions of years lead to very different expectations. Slow movement of the crust over millions of years should result in large differences in the degree of erosion, the amount of subsidence, reef thickness, and reef fossils.
So what do we find?
We’ll start by looking at a series of islands along the Hawaiian Island chain. At the Big Island of Hawaii we see what an actively growing volcanic island looks like, followed by more and more eroded islands. Considering subsidence, the Hawaiian Islands are still mostly above water, but as we continue up through the Emperor Seamounts they dip below the surface. The ocean crust sits lower and lower until near the end where the tops of the former islands are under nearly a mile of water.
Reef thickness also increases with age and subsidence as reefs add layers to keep within the photic zone. At Midway Island, researchers drilled through a thousand feet of reef limestone before reaching volcanic rock. In addition to measuring thickness, fossil reef species were identified in core samples. The species change with depth, with many of those at the bottom found nowhere on Earth alive today.
In each case, the evidence fits old earth expectations.
But it gets even better. Young earth advocates insist that there is no way to tell whether radiometric dating really works, but this is not true. We can conduct a simple test using the islands again.
Many of the islands and seamounts shown have been radiometrically dated. The ages grow older from zero, near the Big Island of Hawaii, to a maximum of 80 million years for the oldest seamount.
If we measure the distance along the chain, and divide by the oldest age, we’ll calculate an average speed of the crust over the hot spot. 3700 miles is roughly 235 million inches. Dividing this many inches by 80 million years gives an average speed of about 2.9 inches per year. If we want to know how much variation in speed there may have been over time, we can measure the distance between individual islands or seamounts and differences in age to calculate the speed over shorter time intervals. When we do this, we get speeds that range from about 2.6 to 3.6 inches per year, suggesting a pretty steady rate over the last 80 million years.
We can actually measure the rate of plate movement today, in real time, using the same GPS technology that allows us to track the speed of a vehicle on the highway. Stations set up on land bounce signals off satellites, which can measure the speed of shifting tectonic plates. Which brings us to the test: if the radiometric dates are correct, we should find that the current measured speed of the Pacific Plate at Hawaii is within the range of 2.6 to 3.6 inches per year. On the other hand, if the radiometric dates are way off, the measured speed should be nowhere close to the calculated rates. So what do we find? The measured speed of the Pacific plate over the Hawaiian hot spot today is averaging 3.1 inches per year. Testing doesn’t get much better than this!
God has given us some amazing tools to test and verify our understanding of earth history!