Today’s New Reason To Believe

by Jeff Zweerink

Earthquakes and volcanos serve as important reminders of the phenomenal forces at work underneath Earth’s surface. The shape and arrangements of the continents change as the massive tectonic plates float across the more fluid upper mantle. This tectonic activity changed the initial, water-covered state of Earth, covering roughly 30% of the planet with continents. Additionally, it replaces continental landmass lost to erosion.

Every few hundred million years all the continents group together to form supercontinents such as Pangaea and Rodinia. Eventually, these supercontinents split up and start a new cycle of continental drift that eventually forms a new supercontinent.

While an abundance of geological data records the motions of the continents over time, scientists have struggled to model such behavior in the lab. However, two New York University scientists have recently built a model that demonstrates cyclic behavior analogous to the recorded continental drift. Their model includes a high-viscosity glycerin/water mixture with heavier-than-water plastic beads (which play the role of continents). The model is heated and cooled in a way reflective of processes operating inside Earth.

When the model was heated and cooled in the absence of the beads, the glycerin/water mixture flowed in a circle for long periods of time without change. Upon adding the beads, the circulation pattern reversed directions every few hours. Thus, they conclude that the continents play a critical role in the cyclic building of supercontinents. The thermal mass associated with the continents affects the flow of rock in the underlying mantle, causing it to change directions periodically. Previous thinking assumed that continents simply rode along on the flow of mantle rock.

Without the flow reversal, the supercontinent would never split apart to begin a new cycle and plate tectonics would eventually grind to a halt. While this change would eliminate earthquakes, the loss of tectonic activity would also rapidly (on geological timescales) lead to an uninhabitable Earth. This research provides scientists with another tool for exploring how well-designed Earth’s interior processes support life.

by Jeff Zweerink

Imagine the Antarctic glaciers extending over the whole Earth. Dating back to the early 1960s, scientists proposed just such a scenario, known as a “snowball Earth” hypotheses to explain various geological and geochemical data in the planet’s history.

According to the proposal, a snowball Earth could possibly form when the planet experiences periods of increased glaciation (or ice ages) due to variations in its orbit around the Sun. As Earth’s temperature drops, glaciers around the north and south poles begin to grow and spread toward the equator. Snow and ice reflect more sunlight than rock, vegetation, and water, causing a further decrease in the global climate. If the glaciers reach close enough to the equator, the increased cooling might result in the complete covering of Earth with glaciers.

During the Cryogenian geological period (850-630 million years ago), two extensive glaciations occurred which may have resulted in snowball Earth. Presumably, continued volcanic action produced enough greenhouse gas emissions to reverse these hypothesized snowball Earth conditions. A thick glacial covering would dramatically impact life on Earth. In fact, these two extensive glaciations immediately preceded the Cambrian Explosion. However, if an abundance of organic carbon sediments covers the ocean floors, then a mechanism exists to prevent snowball scenarios.

An article published in Nature describes the discovery of one preventive mechanism. As the global temperature decreases with the advance of the glaciers, the oceans dissolve more oxygen from the atmosphere. Consequently, this oxygen reacts with the buried organic carbon to produce carbon dioxide, which then enters the atmosphere. The resulting increase in greenhouse heating prevents the further advance of the glaciers.

Because abundant life has existed for about 3.5 to 3.8 billion years of Earth’s history, an ample supply of deep ocean organic carbon has always existed to prevent a snowball Earth. While the snowball Earth hypotheses remain debatable, they do highlight a few apologetic points.

1. A snowball Earth provides one more mechanism that can severely disrupt a planet’s capacity to support life.

2. Scientists continue to find evidence that Earth’s habitability relies on an intricate interplay of geological (glaciation), astronomical (variations in Earth’s orbit), and biological (abundant deep-ocean organic carbon remains) processes.

Both of these points attest to the difficulty, from a naturalistic perspective, of attaining conditions suitable for life. That Earth has remained habitable throughout most of its history comports well with the idea that a super-intelligent Designer fashioned Earth intending to fill it with life.

by Hugh Ross

In the December 2007 issue of Astrobiology Stanford University geophysicists Norman H. Sleep and Mark D. Zoback note that the higher tectonic activity during Earth’s early history could have played a key role in cycling critically important nutrients and energy sources for life.¹ The production of numerous small faults in the brittle primordial crust released trapped nutrients. Such faults could also release pockets of methane gas and molecular hydrogen. The methane and hydrogen could then provide crucial energy sources for nonphotosynthetic life. Finally, the production of faults could bring water to otherwise arid habitats, such as rocks far below Earth’s surface.

Faulting, generated by active and widespread tectonics, allowed a youthful Earth to support diverse and abundant life. This enhanced diversity and abundance of life quickly transformed Earth’s surface into an environment safe for advanced life. Also, the buildup of biodeposits for the support of human civilization occurred more rapidly due to active tectonics.

The more rapid preparation of Earth for humanity is critical. Without such rapid preparation, humans could not come upon the terrestrial scene before the Sun’s increasing luminosity would make their presence impossible (due to excessive heat).² Thus, yet one more reason exists to thank God for His supernatural design of Earth’s tectonics.

1. Norman H. Sleep and Mark D. Zoback, “Did Earthquakes Keep the Early Crust Habitable?” Astrobiology 7 (December, 2007): 1023-32.
2. Hugh Ross, Creation As Science (Colorado Springs: NavPress, 2006): 126-36.