The Earth is constantly changing — it’s a jigsaw puzzle of tectonic plates that exert pressure on one another and generate processes that create oceans and mountains. The rigid plates that make up the Earth’s crust slide on a viscous layer. They are subjected to high pressures and are unable to stop moving.
Yet, these movements are rarely perceptible by human beings. It is easy to understand if we think about them as moving in relation to one another, around 1 inch (2.5 cm) per year, the same as our nails grow, depending on the person.
Various theories state that the current formation of the continents has been caused by these changes, taking place over millions of years. Small movements that divided Pangea, one huge, singular land mass that has been gradually separating since the Triassic period — and continues today. Yet, for a long time, we have been talking about Christopher Scotese’s Pangea Ultima theory, which predicts that all the continents will join back together within 250 million years. Is that possible?
Bearing in mind the activity in the past and with the technology that allows us to measure this now, we are able to predict the future movements of the continents. But, what are the biggest changes happening now?
The specific case of Eastern Africa
One of the prognostics for the Pangea Ultima theory is that Africa will fuse along the Great Rift Valley. “It refers to a fracture in the inner levels of the Earth that Africa runs along, from north to south, from Ethiopia to Mozambique,” explains Joan Flinch. Flinch has worked as a geologist at Repsol for over 10 years, and is now a geosciences consultant for the Company.
Kenya is right in the center of this area, where a large crack appeared recently, causing great alarm. The conjectures, hasty deductions, and some out-of-context scientific conclusions spread the idea that this crack was evidence marking the start of the separation of the continent.
However, once the initial frenzy was over, experts such as Joan Flinch suggested that this breach was probably a consequence of another type of phenomenon, as the area is generally made up of particularly soft and erodible clay soil: “The crack is definitely on top of a contact area between two plates, but that doesn’t mean it was caused by tectonic movement.”
Although this could seem to indicate that the continent is separating, other geologists such as José Martínez Díaz from the Institute of Geosciences at the Complutense University of Madrid, agree with the Repsol specialist that the crack is not a fault line: “The crack was generated almost instantaneously, from one day to the next, and this happening with tectonic plates is unimaginable. A crack like that would take thousands or millions of years to happen”.
So, the crack wasn’t caused by tectonic movements, although activity in the area could have been a contributing factor. Because, in fact, Africa has been splitting into two for thousands of years. According to Flinch, all of Africa is moving east, but the right hand side of the continent is moving slightly faster than the left, causing a relative separation.
However, the Repsol specialist clarifies that geographical accidents like these could have no impact at all: “We have analyzed cases in other parts of the world, which open up but don’t form an ocean. Just like in the Sistema Ibérico mountain range in Spain, to the south of Zaragoza, during the Cretaceous period, where there was separation that never ended up forming an ocean; the same thing occurred in the Carpathian Basin in Hungary and Romania”.
Recently, we’ve been using a technique called seismic tomography that studies the speeds in the deep crust and mantle”, Joan Flinch, geologist at Repsol
Thus, the theory of tectonic plates shows that the Earth’s continents are moving across the length and width of its surface at a speed of a few centimeters per year. We can expect that this activity will continue, and result in the repositioning and collision of plates. This is known as continental drift.
Our advances: seismic tomography
Joan Flinch explains that there are models of plates that predict how the contents will be in the year 3000 or 4000: “Recently, we’ve been using a technique called seismic tomography that studies the speeds in the deep crust and mantle”. This allows us to map out pieces of tectonic plate that have subducted, that is to say, that have sunk into the mantle and can modify their movement and that of other plates. To explain it, Flinch gives us a practical example: “It’s like dunking a cookie (rigid plates) in custard (viscous land asthenosphere). After a while, the cookie breaks apart and starts to form part of the custard, only that the crust stays semisolid for many, many millions of years.”
The current direction of the tectonic plates and their speed allow us to anticipate how the position of the continents will change. Scotese’s Pangea Ultima theory predicts that the Atlantic Ocean will get smaller, bringing America closer to Europe, and that the Mediterranean Sea will disappear as Africa merges with Europe. In the same way, it has calculated that Australia and Southeast Asia will join together.
Scientists have proposed diverse scenarios for how this process will continue in the future. The union of the continents in the areas on the limit between two plates will generate large mountain ranges, similar to the Himalayas. Other existing ranges will also grow. Greenland and Antarctica will move away from the poles, which will cause the sea level to rise worldwide and completely change the coasts as we know them. Most of these events are simple projections, and experts agree that making such long-term predictions is risky. So, one question remains: will Earth become one continent again, like Pangea?