In Vancouver where I grew up, one suburb receives 20 inches of rain a year while another just 20 miles away receives 150 inches. The real estate agent’s mantra, “location, location, location,” holds huge significance in that region. New research shows it also applies more broadly to the arrangement of Earth’s continental landmasses.
An international team of geophysicists has published findings that suggest Earth’s current continental configuration represents something more than a random “lucky-for-life” outcome.1 Their studies confirm that the sizes, shapes, and locations of the landmasses relative to Earth’s oceans and seas play a critical role in determining how much precipitation falls on the continents and where it falls. As it turns out, Earth’s seven continents, positioned as they are and with the specific features they manifest, provide optimal rainfall distribution to support abundant land life—human life and civilization, in particular.
Earlier in Earth’s history, one supercontinent and a single enormous ocean defined Earth’s surface. As much as a billion years ago, multiple forces both internal and external to Earth’s thin, rocky shell caused it to crack, and the pieces began to move. At first the pieces moved slowly apart, and then they came back together again to form a major land area called Pangaea. On this one huge landmass, rainfall would have drenched some coastal regions, with a vast dry wasteland comprising most of its total area.
Approximately 225 million years ago, the seven or eight major pieces, or plates, of Pangaea (in addition to multiple smaller plates) began to split and drift slowly apart once again. About 150 million years ago South America was still connected with Africa and Europe (see figure 1, middle). Just 100 million years ago South America finally split off from Africa. As recently as the last ice age, about 40–60 thousand years ago, much or most of the Red Sea region was dry land.
PERMIAN - 225 Million Years Ago
TRIASSIC - 200 Million Years Ago
JURASSIC - 150 Million Years Ago
CRETACEOUS - 65 Million Years ago
Credit: United States Geological Survey
Figure 1: Continental Landmass Redistribution over the Past 225 Million Years
Earth’s fine-tuned plate tectonics has transformed Earth’s land mass from a single precipitation-starved supercontinent into seven wellseparated smaller continents where rainfall on the continents not only has increased but also is much more evenly distributed.
Today Earth’s surface has become the well-distributed (and yet still slightly moving) set of seven continents, four oceans, and some large seas supporting several billion people as well as other animals on which they depend. Researchers now recognize that this exact arrangement of continents, oceans, and seas maximizes the amount of land area receiving sufficient precipitation to sustain widespread human civilization.
Not only are the continents appropriately dispersed, but they are also oriented to provide powerful northsouth barriers to the prevailing winds and ocean currents. This orientation evens out both temperature and precipitation levels across the continents. The continents’ specific placement, with more than twenty times as much land area between 35 and 65 degrees north latitude as between 35 to 65 degrees south latitude (see figure 2), also serves to moderate continental temperatures. Because Earth’s (current) orbitbrings the planet closest to the Sun during the northern hemisphere’s winter, summer–winter temperature differences for the vast majority of humans remain relatively mild. (Seasonal differences are minimal for latitudes closer to the equator, regardless of when Earth passes closest to the Sun.)
Credit: Reto Stöckli/GSFC/NASA
Figure 2: The World’s Continents
Notice how little land area is located between 35-65°S compared to that located between 35-65°N.
To their surprise, the research team discovered that the largest oceans, including the North Pacific, the Southern Indian, and the South Atlantic, deliver far less precipitation to the continents than do the smaller oceans and seas. About 90 percent of ocean precipitation falls back into the ocean, rather than onto the land. The subtropical North Atlantic and the Mediterranean and Red Seas supply most of what’s needed on the populated continents.
The Indian subcontinent receives precipitation from as many as six ocean regions, and this rich supply is one reason it can support such a large number of humans and other animals. Yet it wasn’t always this way. Ninety million years ago the Indian subcontinent was located in the southwest region of the Indian Ocean. Not until ten million years ago did the Indian subcontinent make contact with the south central Asian plate (see figure 3).
Credit: United States Geological
Figure 3: Movement of the Indian Subcontinent over the Past 70 Million Years
The Indian Plate is the fastest moving of all Earth’s tectonic plates. After breaking off from Antarctica and Madagascar, it proceeded at a rate of eight inches per year toward Asia. Since colliding with Asia about ten million years ago, it is continuing to move in a northeast direction at a rate of two inches per year. This ongoing movement will push up the Himalayas to even greater heights.
It’s worth noting that despite how widely dispersed the continents are, the lowered sea levels resulting from the last ice age exposed land bridges that joined Britain, Sri Lanka, Indonesia, Japan, and the Philippines to the Eurasian continental mainland, Australia to New Guinea, and Siberia to Alaska. These bridges facilitated the global spread of humanity from their starting point near the junction of Africa and Eurasia.
Given the number of these positioning “coincidences” and the fact that all of them provide specific benefits to humanity for the launch and sustenance of global civilization, to infer the Creator’s hand on the forces that shaped Earth’s crust seems entirely reasonable—more reasonable than to attribute the outcome
1. Luis Gimeno et al., “On the Origin of Continental Precipitation,” Geophysical Research Letters 37 (July 2010): CiteID L13804.