Evidence of Early Plate Tectonics
Finish the sequence of early Earth transformations: light, water, ______. Did you guess earthquakes? These are the first three miraculous transformations of Earth recorded in the first chapter of Genesis. The first “day” brought the day/night cycle; the second resulted in a stable water cycle; and on the third day we see the arrival of landmasses. (Technically the answer should have been land, but plate tectonics results in land and earthquakes—the latter of which are more exciting.) New scientific evidence affirms the antiquity of plate tectonics.
It is relatively obvious that life depends on light, water, and land. Light from the Sun is an energy source for most life on Earth. Life’s biochemical reactions cease without liquid water. And the majority of life on Earth lives in environments made possible by land (including the continents and continental shelves). Without plate tectonics operating early in our planet’s history, Earth would have never been able to support advanced life.
Plate tectonics plays a critical role in keeping the Earth’s temperature constant during the Sun’s significant brightness changes. Almost four billion years ago, the Sun was 30 percent dimmer than it is today, and it has steadily increased its light output over the intervening period. This steady increase would have boiled Earth’s oceans away without plate tectonics moderating the greenhouse gas content of the atmosphere. Also, as mentioned above, without plate tectonics, continents cannot form nor could majestic mountains grow. While continents and mountains provide many different environments for abundant life, their erosion from the water cycle supplies nutrients that a diverse biosphere requires.
Numerous lines of evidence point to the fine-tuning that plate tectonics require. But an article in Science affirms that this critical process has operated for most of Earth’s history.1 Specifically, studies of the Slave craton in Northwest Canada reveals that it formed via subduction processes nearly 3.5 billion years ago. As the Earth’s tectonic plates bump into one another, sometimes one plate is forced underneath the other (called subduction) and falls back toward the mantle. This process results in the formation of the less-dense rocks and minerals that form the continental plates.
Plate tectonics plays a critical role in maintaining and diversifying Earth’s habitability. That such a critical process has operated for over three billion years affirms the biblical account of Earth’s transformation where the water cycle and the tectonic cycle prepare land in anticipation of human arrival.
- Chin-Wu Chen et al., “Geophysical Detection of Relict Metasomatism from an Archean (~3.5 Ga) Subduction Zone,” Science 326 (November 20, 2009): 1089–91.