Today’s New Reason To Believe

by Jeff Zweerink

I love mountains! Most of my favorite trips from childhood (and adulthood) involved mountains–backpacking in Bridger Wilderness Wyoming; rafting the Arkansas River through Brown’s Canyon, Colorado; enjoying the ski slopes of Monarch Pass in the Colorado Rockies. All of these destinations, including my most recent excursion to the Grand Tetons (just south of Yellowstone National Park), feature mountain peaks reaching well over 12,000 feet above sea level.

Colter Bay in the Grand Tetons.

Recent research shows that for half of Earth’s history such vistas did not exist. The processes that formed the Earth left it with a surface and interior much hotter than today. Collisions during the late heavy bombardment maintained this hellish state. Extreme heat makes most materials less rigid and sturdy. Consequently, the rocky substance that comprises Earth’s crust was too weak to permit the formation of mountains any larger than about 7,500 feet. Over time, Earth radiated enough heat away that the crust grew much stronger. Between 2.8 and 2.5 billion years ago, it became strong enough to support mountains taller than 7,500 feet.

This dating is significant because of how tall mountains affected Earth’s atmosphere and geochemistry. Around this same time, our planet’s atmosphere changed to a state containing a permanent oxygen component (although initially only a few percent of present levels). Yet the geological record indicates that up to 300 million years elapsed between the time when oxygen-producing bacteria came into existence and when the permanent oxygen component appeared. The simultaneous formation of tall mountains and this atmospheric constituent may help explain this gap.

As I wrote in the January 2009 issue of our new magazine, New Reasons to Believe, the abundance or lack of nutrients affects the activity of oxygen-producing bacteria. In particular, the lack of the element molybdenum severely limits bacterial activity. The erosion of continental crust provides the primary source of this element, and tall mountains greatly facilitate erosion. The increase of molybdenum in the geological record coincides with the time that the crust became strong enough to support mountains above 7,500 feet. Subsequently, the oxygen content of the atmosphere increased to the current 20 percent level that complex life like human beings requires.

Genesis 1 describes a process where God transformed an initially uninhabitable, water-covered world to an environment teeming with life. One overriding purpose of this transformation is to provide an abundant, beautiful place for human beings to reside. The intricate interaction of biological (oxygen-producing bacteria), astronomical (Earth radiating heat away into space), geological (plate tectonics building tall mountains), and chemical (erosion of nutrients like molybdenum) processes fits perfectly with the careful, purposeful progression Genesis 1 describes.

by Jeffrey Zweerink

From a biblical perspective, the advent of continents plays a critical role in God’s transformation of Earth from “formless and void” to an environment teeming with diverse life-forms. In fact, the formation of continents warrants mention as one of the miracles performed on the third day of creation. The formation and motion of continents plays an important role in the history and development of Earth’s habitability from a scientific perspective as well.

A recent discovery provides further evidence that the Earth's continents have moved and changed dramatically over time. Around one billion years ago, the bulk of the continental landmass was clumped together into a supercontinent called Rodinia. Around 800 million years ago, Rodinia began to break up, causing Earth to plunge into the Cryogenian period. During this period, glaciers covered nearly the whole Earth numerous times in events called "snowball Earths".

Shortly (on geological timescales) after the end of the Cyrogenian era, diverse, complex organisms explosively appeared on Earth. The Avalon explosion and the Cambrian explosion represent two such events. Some scientists argue that the change in Earth’s surface that occurred during the Cyrogenian played a critical role in the subsequent introduction of diverse life. Many of these changes resulted from the breakup of the Rodinia supercontinent.

In typical models for Rodinia’s topography as shown above, the North American continent (referred to as Laurentia) sits next to East Antarctica. After the breakup of Rodinia, the continents drifted apart and back together a couple of times until they ended up in their current configuration. Recent finds in Antarctica support this model by demonstrating that rocks unique to North America also exist in Antarctica. Three lines of evidence point to a juxtaposition of East Antarctica with North America:

1. Geological: similar strata found in both locations
2. Dating: zircons in the rock formations of both continents date to the same age
3. Isotopic: the chemical composition of the granites in both locations match

For most of Earth’s history, only single-celled organisms lived. Yet shortly after the tumultuous Cyrogenian era, an abundance of advanced, multicellular organisms quickly appeared on Earth. The breakup of supercontinents led to dramatic changes on Earth’s surface and, in the case of the Rodinia breakup, led to environments where more-advanced life could not only survive, but flourish. Such results fit comfortably in a model where a supernatural Designer is transforming an otherwise desolate planet into an environment suitable for advanced life, particularly humans.

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.