The Alps are built
Africa pushes into Europe, and the seafloor between them is folded up into mountains.
- When
- —
- Duration
- 16 million years
- Known to
- ± 5 million years
- Era
- Eocene, Cenozoic
As Africa converges on Europe the Tethys ocean floor between them is consumed and the sediments that lay on it are scraped up, stacked in vast overthrust sheets and lifted. The result is the Alps, where marine limestone now sits at 4,000 metres. The nappe structures exposed there — sheets of rock carried tens of kilometres over other rock — were the observations that forced nineteenth-century geologists to accept horizontal crustal shortening on an enormous scale, decades before plate tectonics explained why.