Over the last 50 million years, tectonic shifts in the Earth’s crust caused by forces deep within the mantle have caused the Caribbean island chain to be pushed Eastward. Staring at a map will reveal the bulging shape of the lesser Antilles way out into the Atlantic. A new study by researchers from the University of Southern California has found the reason for this movement to be the South American plate. The South America is far larger and more heavily rooted in its location. The Caribbean movement to the east is caused by the underlying mantle pushing against the southern continent.