Blowhole
A blowhole (geologically called Gloup - from Old North. Gluppa, dt. Blowhole ) is in parlance and in geology a narrow opening at the end of a sea cave, which extends over the cave ceiling up into the open. When a surf wave hits the mouth of the cave, it is led through the cave walls, like in a funnel, to the blowhole, which, given the appropriate geometry of the cave and the right weather conditions, leads to spectacular water fountains .
Well-known blowholes on different continents
- In Europe , the coasts of the British Isles are particularly affected. The blowholes formed there in the limestone (geologically called Gloup - from old north. Gluppa) can be found, for example, in the Smoo Cave ( Highlands ) and on the coast of Orkney (Gloup of Deerness, Gloup of Stroma ), Vat of Kirbuster Stronsay , and on the Shetland Islands (Gloup of Yell ).
- The Kiama Blowhole at Kiama in New South Wales , Australia is probably the largest blowhole in the world.
- Asia : In Oman you can marvel at a number of blowholes on the beach of Mughsail , approx. 20 km west of Salalah . Depending on the tides and the swell , you can marvel at sea water fountains that shoot out of the ground at regular intervals. The best time is during the Charif .
- In New Zealand , for example, blowholes can be found at the so-called pancake rocks .
Blowholes in country caves
The term blowhole is also used for a rare geological phenomenon in which the pressure difference between a closed cave system and the surrounding area causes the air to be blown out or sucked in through a small hole on the surface. Among the best known blowholes of this type are the blowholes near Flagstaff in Arizona. It is estimated here that a cave system with a volume of at least 200 million m³ is connected to the holes. The wind speeds can reach 13.4 m / s.