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The Horror of Sea Hedges! December 22, 2012

Author: Beach Combing | in : Medieval , trackback

The Norse had a whole series of sea-monsters ready to gobble up unwary sailors: the kraken, the hafstramb (the Norse merman) and other saline lovelies. But at least to this blogger’s mind the worst of all was the Hafgerdingar, ‘the Sea Hedge’. Perhaps the nightmare quality of the Sea Hedge comes from the fact it is not really a lifeform at all but a malevolent act of the entire ocean. Or perhaps it is that homely sounding ‘hedge’ in such a devilish form, drowning by privet. Here is the classic description:

Now there is still another marvel in the seas of Greenland, the facts of which I do not know precisely. It is called ‘sea hedges’, and it has the appearance as if all the waves and tempests of the ocean have been collected into three great heaps, out of which three billows are formed. These hedge in the entire sea, so that no opening can be seen anywhere; they are higher than lofty mountains and resemble steep, overhanging cliffs. In a few cases only have the men been known to escape who were upon the seas when such a thing occurred. But the stories of these happenings must have arisen from the fact that God has always preserved some of those who have been placed in these perils, and their accounts have afterwards spread abroad, passing from man to man. It may be that the tales are told as the first ones related them, or the stories may have grown larger or shrunk somewhat. Consequently, we have to speak cautiously about this matter, for of late we have met but very few who have escaped this peril and are able to give us tidings about it.

The obvious explanation here is that we are dealing with a tsunami of some kind, perhaps set off by a land or marine earthquake. The problem is that tsunamis tend to be a coastal phenomenon – ocean boats ride them out – and they do not really explain the ‘three billows’. Beach has long wondered about the Sea Hedge and was interested to read that in 2002 a group of scholars (Lehn and Schroeder, Polar Record 39) made the suggestion that the Sea Hedge was nothing more than an optical illusion. Any other suggestions: drbeachcombing AT yahoo DOT com They produce some striking descriptions from northern latitudes where water seems to stand above the ocean: significantly this typically presages a storm. Science is a foreign language to Beach but here for what it is worth is the physics:

A mirage of this type is seen when a strong, well-defined temperature inversion surrounds the observer. This can happen when warm air moves over cold water or ice. The air is thus cooled from below, producing an atmosphere in which the temperature increases with elevation (this is the inversion — a reversal of the normal decrease of temperature with height). Because the lowest layer is the coldest, it is also the most dense. Successive layers above it have decreasing densities. This creates a stable, layered atmosphere in which there is no inherent tendency toward mixing of the layers. The situation can last for hours. Consider the effect when a distant object is observed from a low vantage point, such as the deck of a Norse ship. The line of sight will be nearly horizontal,more or less parallel to the atmospheric layers. The light rays that make up the view through such an atmosphere are refracted downward (towards the denser medium) as they proceed. Therefore each ray will describe an arc, concave downwards, on its path to the observer.

The mirage is static in the same way that the Norse text quoted above suggests: ‘steep, overhanging cliffs’. We’ve included one photograph from the article at the top of the post. It shows the mirage effect in Iceland. Note the ship in the foreground on the horizon, the Hafgerdingar beyond. Imagine now that you are on a tiny Viking boat in the Davis Strait no land in sight and that thing rears up… You know that there are about twenty centimetres of rotten maple between you and a thousand and more metres of Arctic Sea.

Any other sea phenomena? drbeachcombing AT yahoo DOT com


24 Decem 2012: Lots of emails on this all alleging rogue waves (see below for some samples). Two small counter points. The word ‘hedge’ and the description suggests that the ship is surrounded by these great waves. The danger is not illusory as a storm is on the way. However, having said this the following make for persuasive reading. Lehmansterms writes: Although the optical illusion, “mirage sea” is certainly a possibility and I can see where it may have terrified early mariners who did not have any way to understand the phenomena they were observing, I think this passsage is important in this story: “…In a few cases only have the men been known to escape who were upon the seas when such a thing occurred…” I wonder whether this mention of all but a few of those mariners observing it presumably perishing might not indicate that a real and deadly phenomenon was being described. What this brings to mind for me is the so-called “Rogue Wave”.  Long thought to be the province of mariners’ tall tales, a convenient excuse for the loss of a vessel or crewmembers in reports from unwary sailors - or the result of a double ration of rum – it is becoming clear to modern oceanographic science that waves can be multiplied in size by a frequency/harmonic effect that stacks one small wave upon another until 100′ (or taller) waves can occasionally be generated.  Many ships have not returned after seeing this phenomenon – and presumably only a very few of their occupants might have escaped and survived to relate the story of the occurrence.  Long regarded rather like the reports from those who swear they see UFO’s – ie: with ridicule – the rogue wave was considered to fall into that “Here be Sarpents” category of map marginalia. In the new age in which virtually everyone has immediate access to live video recording, some reports of ships encountering preternaturally large waves out of an otherwise clear sea are now being accompanied by live video of  singular 100+’ waves breaking over the bows of a superfreighters or cruise ships which barely survived the encounter. I wonder if a conflation – whether actually coinciding or merely being confused – of the undeniably true mirage phenomenon and the equally true occurrence of actual rogue waves might not be the root cause of these reports. Mirages by themselves can hardly be to blame for fatalities on the sea.  Unless the first passage suffers from terrible exaggeration, it certainly sounds as though the phenomenon which described is to blame for actual disappearances of ships and mariners. Nathaniel writes in: The possibility of the ‘sea hedge’ being a rogue wave immediately leaped to mind:  These waves were reported by mariners for centuries and caused serious damage to the ships they didn’t sink. One account of such a wave said it looked “higher than the moon”. But their existence was pretty much denied by science until recently, since they didn’t fit any accepted theories of wave formation. If even that much anecdotal evidence can be discounted it makes you wonder how much else science is overlooking.’ Next up is the Count: I think you’re on the wrong track with the optical illusion theory. While it’s perfectly true that tsunamis are irrelevant in mid-ocean, only becoming a problem when they hit land, other rare types of wave exist which are completely different in both cause and dynamics. However, it was only within the last couple of decades, mainly due to one such wave hitting a North Sea oil rig on January 1st 1995, that mainstream science was entirely convinced that they weren’t just tall stories. As the references below will show you, these thankfully infrequent waves are terrifyingly gigantic, and can be a major problem even to huge modern ships – if you’re in a Norse longship, your only recourse is prayer! You will observe that these modern reports are almost perfect matches for the ones you quote, so in this case it’s reasonable to assume that the few survivors gave an accurate account of a bloody great wall of water that smashed their boat. Besides, would those big manly Vikings have been that terrified of something which initially looked fearsome but never did any actual damage? And they do state specifically that “sea hedges” are physical phenomena which literally destroy your boat and kill you. Attempts to turn this into hysteria based on an optical illusion are simply skeptics trying too hard to explain away something they consider unlikely in a ludicrously torturous fashion, in the same way that the notorious “swamp gas” explanation for certain early UFO sightings was so convoluted that it became less likely than the bizarre theories it was trying to discount. Here’s a piece on rogue waves. And here’s a laboratory recreation of a sea hedge, which demonstrates how dangerous even a tiny little one can be if you’re a pirate made of Lego:  So there you are – sea hedges are a real thing that can cause seafarers all kinds of grief! Just when you thought it was safe to go back in the water… Note the interesting fact that the version of this phenomenon found in lakes sometimes comes in threes. If you know anything about the physics of waves (or indeed any physics at all, since waves are pretty basic physics), it may already have occurred to you that Loch Ness, with its peculiarly simple and regular shape – basically it’s a very big ditch – would be an exceptionally favorable environment for the spontaneous creation of triple lumps of water that that look a lot like a huge animal with three humps… Rebis writes in: the optical illusion sounds believable, but optical illusions don’t kill people, as the account mentions. A tsunami at sea is only a large  swell which rises when it enters shallow water. Another possibility is a rogue wave. These can reach heights of well over 100 feet. These giant rogue waves can even form in the great lakes in north america. See wreck of the Edmond Fitzgerald. A rogue wave snapped the 711 foot long Edmond Fitzgerald in half sinking it immediately. Another ship ten miles away was not effected. These lackers would tie up for the winter where I grew up. I once had a tour of one, you have no idea how absolutely huge they are. That it is possible to instantly sink  a ship that big is a testament of the power and reputation of  rogue waves.’ Then Ralph writes with a personal Rogue Wave story: ‘In October 1965, I was aboard the USS Essex(CVS-9) in the Atlantic well off the east coast of the U.S.  We were on our way to be the primary recovery ship for one of the Apollo missions.  The capsule was to splash down in the Atlantic, and our aircraft were to pinpoint it, a helicopter was to lower a swimmer into the water, who would attach a collar to the space capsule, and capsule and crew were to be retrieved by the ship. We never got there.  On a perfectly clear day, with calm seas, we were struck by a rogue wave of sufficient height that it damaged the number 2 elevator of the ship so badly it could not be raised back up to deck level.  Of necessity, we returned to homeport for repairs, and the backup ship did the recovery.  I remember this very well.  As a result of this mishap, I was home for the birth of my eldest son.’ Thanks to all those who wrote in on this theme!!