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Pitch wells – Geological phenomenon 

There have been many reports recently about strong smells of tar/oil in the Keri area of Zakynthos. These reports state that the smells occurred around the time of some recent earthquakes. Experts are saying that the smells are emanating from local pitch (tar) wells/ tar springs, situated in the Keri area. Many are dispelling this as rubbish saying there is no such thing as pitch (tar) wells/springs on the island and feel that they are being mislead. There is however, much historical/written evidence, going back hundreds of years, that fully supports the experts, confirming that not only are there pitch wells on Zakynthos, but that these pitch wells have been active for a very long time, and that the tar from them was actually a very valuable resource for islanders. 

So what are pitch wells?

Sometimes known as tar pits, or asphalt lakes, pitch wells are a natural geological phenomenon that’s created when petrol or oil travels through cracks in the earths lower layers, eventually making its way to the surface. The petrol/oil is forced to the surface by low pressure, either by natural phenomenon or helped by seismic or geological activity in the area. It’s thought that the more activity the area has, the higher the rate of petrol/oil flow. Sometimes these petrol/oil leaks are small resulting in tar pits or wells, on other occasions they are much larger and entire lakes are formed. When the liquid reaches the surface, lighter parts of the liquid vaporise leaving behind the substance we know as bitumen. It’s this product that causes the smell similar to tar or oil. A petroleum based hydrocarbon, bitumen, is very viscous, sticky and black in colour, and it’s a very common product that’s found all over the world. Bitumen is also known as asphalt, a name first given to it around 625 B.C by the Ancient Greeks who called it “Asphaltos” meaning secure. It was also used in Babylon for building roads and by Romans for aqueducts, bathhouses and reservoirs.

Past accounts of Bitumen by Travellers to Zakynthos

Many travellers visiting Zakynthos, from Herodotus to Gentlemen Travellers of the 1800’s, have been fascinated by Zakynthos’ pitch wells leading these visitors to write interesting accounts about locating and investigating them. Herodotus Histories, mentions Herodotus’ trip to Zakynthos – sometime before his death in 425 B.C – and he noted that he saw a lake and wells on the island that produced bitumen. He is quoted as saying:

“for I myself saw pitch drawn from the water of a pool in Zakynthos. The pools there are numerous; the greatest of them is seventy feet long and broad, and twelve feet deep. Into this they drop a pole with a myrtle branch fastened to its end, and bring up pitch on the myrtle, smelling like asphalt, and for the rest better than the pitch of Pieria. Then they pour it into a pit that they have dug near the pool; and when a fair amount is collected there, they fill their vessels from the pit. Whatever falls into the pool is carried under the ground and appears again in the sea, which is about a half a mile distant from the pool.”

Herodotus, Histories, Book four

Many other gentlemen travellers between the 1600’s and 1800’s also wrote about visiting pitch wells in the same area of Zakynthos, and it seems that they were a popular destination. One description from the 1800’s describes a beautiful plain of three leagues [approx. nine miles] in size surrounded by mountains. The writer described the air as noxious with ability to cause fevers and other illness. At the centre of the plain he found two “bitumen springs” around 200 paces apart. He described the springs as boiling and bubbling with a strong smell. Remarkably though, it was also noted that water surrounded the bitumen itself, and this water was perfectly cool and clear, even on the hottest of summer days. The water in one spring was sweet tasting , in the other spring it was salted. The traveller noted that the bitumen was most violent during earthquakes and many islanders he met at the time took this as proof that the bitumen and earthquakes came from the same source. 

Another account from a gentleman traveller hundreds of years ago, wrote that Zakynthian residents used the highly sought after bitumen for a multitude of purposes. The bitumen in the islands springs often overflowed, and locals would visit them with their buckets to collect the substance. It was stored in leather bags or casks and sold on to be exported for use in many products. Islanders also used it to coat boats and roofs and some say it was even used for ladies medicine! Sailors with scurvy were reportedly given water to drink from the one of the wells with an aim to remedy the illnesss. The bitumen was also dried in the sun and used as cement. 

So should we worry?

Those who have, in the past, studied the bitumen springs and seismic action on the island, have noted that these springs and the often felt earthquakes, were not the only indications of seismic activity. Close to the shore at Xigia there is a spring of sulphurous water. The smell from it is powerful and in the past many locals used it to cure livestock illness. Deep caverns located near Cape Skinari, and at Keri have also showed signs of a white oily substance that would rise to the surface and settle on top of the water, previous visitors thought it was another form of bitumen, but it this was never confirmed. The sulphurous water, and oily substances are all known “side effects” of seismic activity.

Nowadays the original pitch lake that Herodotus described, more commonly known as Limi Keriou is now just marshland, but there are still some pitch wells visible, the most notable being Herodotus Spring to the west of Limi Keriou, close to Herodotus Studios and Herodotus supermarket.

The latest news of active pitch wells is nothing new for Zakynthos, as readers will note, this phenomenon has been going on for a very long time and it part of the islands varied geological history. The island has coped with it for a very long time and residents used to live side by side with it, even utilising the bitumen and making money from it, something that may likely continue on for a long time yet to come.

About Chrissie Parker

Chrissie Parker joined the Zakynthos Informer Team in 2014. Chrissie’s first experience of the island was a combined birthday and wedding celebration, in true Zakynthian style. Since then she has been able to combine her love of the island, including its incredible history, tradition and culture, with her love of writing.

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  1. A very interesting read, well worth learning something new about the island.

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