Since all of the world's continents are merged into a single supercontinent, maps that look like today's Earth aren't quite right. Dinosaurs in South America and Africa were explained by the maps.
The processes that shape our planet are the result of plate tectonics, volcanism, and mountain building, and their interactions with the oceans, atmosphere, and sun. The past ten years have seen the development of software that allows anyone to make reconstructions.
If paleogeographic maps were already in our primary school textbooks, what are geologists trying to uncover? Just the details?
The details of plate motions in the distant past may make a difference.
When water suddenly flooded through the Straits of Gibraltar and filled up the Mediterranean, the major ocean currents suddenly changed course.
There are subtle differences in the timing or location of corridors that may support or deny the cause of climate change.
The biggest problem for paleogeography is not the details, it's the fact that as much as 70% of the Earth's crust was lost to subduction as recently as 150 million years ago.
We have filled in those areas on paleogeographic maps with the simplest possible scenarios.
In my field of research, we try to use the relics of the subducted crust left in the geological record to learn about the lost surface.
The Himalayas are made of folded and stacked slices of rock that were removed from the subducted plate. The types of rock and the fossils they contain can tell us when and where these rocks were formed.
The continents and deep basins and volcanoes are linked together in the distant past.
Mountains 200 million years from now.
I was asked if we could predict future mountains when I explained how we make paleogeography from modern mountain ranges. "Sure, but why would I?" I always asked. I would have to wait a long time to see if I'm right.
This could be an interesting thought experiment. Predicting the architecture of future mountain ranges would require a set of 'rules of mountain building', which had not been done before.
Predicting how the geography would transform into mountain belts would make us realize what the plates that were lost forever could have looked like. Would we make mountain belts that look like the ones we have?
We did. The rules were formulated by comparing features in mountain belts. The rules were used by Thomas Schouten to predict the geological architecture of a mountain belt that will form in the next 200 million years if Africa and India collide.
The 'Somalaya mountains' might be the Himalayas of their day. Seeing similarities between the mountains today can provide us with possible solutions for paleogeographic evolution.
A mountain belt may form in the bay between Africa and Madagascar and it would be similar to the Carpathians of Eastern Europe or the Banda islands of Indonesia.
northwest India will first get buried under a large part of the country, but then it will come back, and this geological history looks a lot like western Norway around 400 million years ago.
Experiments like our look at the Somalayas help us realize what we don't know when reconstructing the history of the Earth's plates and surface. The better those reconstructions are, the better we will be able to predict Earth's history and behavior.
The Chair in Global Tectonics and Paleogeography is held at the University of Utrecht.
The Conversation's article is a Creative Commons licensed one. The original article can be found here.
