10 September 2024: Day 4, Tarifa and birding on the Strait of Gibraltar, WINGS Spain in Autumn. Click on right here for a map displaying the place I’m as we speak.
We at the moment are on the Strait of Gibraltar, the closest level between Europe and Africa. At its narrowest the Strait is just 13 km (8.1 miles) throughout, flanked on either side by mountains.
The passage is longer east-to-west than it’s extensive –> 58 km (36 miles) from starting to finish. Its present, water stream and variable depth give scientists clues as to the way it was fashioned.
Water flows via the Strait kind of constantly, each east and west, however the steadiness of water strikes eastward from the Atlantic into the Mediterranean. That’s as a result of the Mediterranean evaporates quicker than tributaries and precipitation can fill it. The Atlantic pours in however the Mediterranean stays saltier than the Atlantic Ocean.
In actual fact, Mediterranean waters are a lot saltier that they sink beneath the continually incoming Atlantic and type a heat extremely saline layer of backside water referred to as a thermohaline. You’ll be able to see this within the schematic of the Camarinal Sill which is west of the Narrows.
Whereas the Camarinal Sill is the shallowest level (280 m = 920 ft deep), the deepest level is on the Narrows (900 m = 3,000 ft deep). Deep water is black on this underwater topo map.
With solely 25km (15.5 miles) between the 2 factors the stream typically generates inside (subsurface) waves that may be seen from satellites.
About 6 million years in the past plate tectonics(*) closed the connection between the Mediterranean and the Atlantic. With out an inflow of water the complete Mediterranean Sea evaporated, forsaking salt and gypsum deposits. This Messinian Salinity Disaster lasted roughly 700,000 years. Then, relatively abruptly, a leak developed between Africa and Europe. It rapidly eroded a deep channel to the Mediterranean and eroded backwards (upstream) to create the Gulf of Cadiz. This video of an experimental dam failure exhibits how that appears.
The Zanclean Flood occurred fairly quickly! The Mediterranean stuffed up inside two years!
90% of the Mediterranean Basin flooding occurred abruptly throughout a interval estimated to have been between a number of months and two years, following low water discharges that would have lasted for a number of thousand years. Sea stage rise within the basin could have reached charges at occasions higher than ten meters per day (30 toes per day).
The result’s an underwater topography carved by the flood. This diagram exhibits the marine ground however is to not scale (described beneath). It comes from ScienceDirect: The Zanclean megaflood of the Mediterranean – Looking for unbiased proof — Daniel Garcia-Castellanos et al.
Everybody needed to run away from the flood whereas the Strait was being fashioned.
(*) p.s. Plate tectonics closed the Strait 6 million years in the past. At current the African Plate is subducting beneath the Eurasian Plate within the Mediterranean area. Africa is slamming into Europe, albeit very slowly.
