10 September 2024: Day 4, Tarifa and birding on the Strait of Gibraltar, WINGS Spain in Autumn. Click on right here for a map exhibiting the place I’m at the moment.
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 huge –> 58 km (36 miles) from starting to finish. Its present, water circulation and variable depth give scientists clues as to the way it was shaped.
Water flows by the Strait roughly constantly, each east and west, however the stability of water strikes eastward from the Atlantic into the Mediterranean. That’s as a result of the Mediterranean evaporates sooner than tributaries and precipitation can fill it. The Atlantic pours in however the Mediterranean stays saltier than the Atlantic Ocean.
The truth is, Mediterranean waters are a lot saltier that they sink under the always 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 circulation typically generates inner (subsurface) waves that may be seen from satellites, although they don’t seem like waves in floor navigation.
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 whole Mediterranean Sea evaporated, abandoning salt and gypsum deposits. This Messinian Salinity Disaster lasted roughly 700,000 years. Then, moderately immediately, 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 might have lasted for a number of thousand years. Sea stage rise within the basin could have reached charges at occasions better 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 under). It comes from ScienceDirect: The Zanclean megaflood of the Mediterranean – Trying to find impartial proof — Daniel Garcia-Castellanos et al.
Everybody needed to run away from the flood whereas the Strait was being shaped.
(*) 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.
