Drink!

[Mick Harper]

The Ljubljanica Gap is arguably unique though Berkshire's Goring Gap, if artificial, would gainsay its uniqueness.

Blimey, that's bold. The Ljubljanica Gap leads to the German Stonehenge. Where does the Goring Gap lead to?

[Boreades]

The Unica flows underground more than above ground which is pretty weird.

Err, weird in what sense?

Whether it's chalk or limestone, it's quite normal for some entire rivers to disappear underground.

Which reminds me, as a child growing up in Devon, we used to go caving and exploring in the chalk and limestone caves at Chudleigh, Ashburton and Buckfastleigh, which still had sub-surface streams and rivers flowing through them. Off the top of my head, the same is true in places like Somerset (see Cheddar Gorge), Derbyshire and Yorkshire (Tisi to vouch for the latter)

[Boreades]

Some people think that 'chalk is weird' so perhaps others are out there wondering about it. Perhaps it's like the fish in water who doesn't know what water is all about?

Agreed, chalk is weird for a rock, but the flint in the chalk is even weirder. No-one seems to know where flint really came from, just that "it's there", with lots of assumptions that it was formed by some kind of marine lifeform, but there's bugger-all evidence for a what that lifeform might have been.

Flint is chert that occurs in chalk, that is to say cryptocrystalline silica, black, shiny and with conchoidal fractures. It is extremely common, but no-one really knows how it forms. The silica doesn’t come from sand like in normal sediments, oh no, it is thought to come from sponge spicules, diatoms and other biological sources. It is formed somehow during diagenesis. Often it infills burrows or surrounds fossils, suggesting a role for micro-environments with unusual (weird?) chemistry that allow the silica to precipitate out as a gel. Sometimes soft-sediment deformation is seen to deform flints, so they are soft during early stages of diagenesis. Also flint sometimes infills early faults/fractures to form sheet flints. It can also directly replace chalk, rather than filling cavities. As a resistant erosional product, flint is ubiquitous in Southern England (it forms the gravel drive of my house) yet nobody really knows how it forms.

[hvered]

The German Stonehenge is Goseck (51° 11′ 54″ N). What connection does it have with the Ljubljanica Gap in Slovenia (46° 3′ 20″ N, 14° 30′ 30″ E)?

The Goring Gap doesn't seem weird unless you look at the map. It's where the chalk ends.

The chalk features that are most remarkable (to me) are 1. Grimes Graves and 2. 'sea gates'. Grimes Graves are odd because prehistoric mines are on the surface, as we discussed on the AEL site. The sea-gates are cuttings through chalk cliffs that connect places to the sea.

[Mick Harper]

it's quite normal for some entire rivers to disappear underground.

That is not what Hatty said.

The Unica flows underground more than above ground which is pretty weird

I have no idea whether this is true or whether it is significant but since you have raised the point, do any of the rivers you mentioned, or any rivers of your acquaintance, whether in limestone or in chalk, in fact flow more under than overground. Leaving aside Bulgaria. And (Hatty can join in with this) how would anyone know given the current speleological database.

[Boreades]

The Ljubljanica Gap is arguably unique though Berkshire's Goring Gap, if artificial, would gainsay its uniqueness.

Blimey, that's bold. The Ljubljanica Gap leads to the German Stonehenge. Where does the Goring Gap lead to?

The Ljubljanica Gap should feature in UHOTSWW myth-busting.
http://forum.axishistory.com/viewtopic.php?t=153670

Whereas the Goring Gap just leads to Goring (and Streatley).
You can, if you wish, try and make sense of the official version:
https://en.wikipedia.org/wiki/Goring_Gap

[Boreades]

it's quite normal for some entire rivers to disappear underground.

That is not what Hatty said.

The Unica flows underground more than above ground which is pretty weird

Hatty kindly mentioned one example of a general case. I merely replied mentioning the general case.

I have no idea whether this is true or whether it is significant but since you have raised the point, do any of the rivers you mentioned, or any rivers of your acquaintance, whether in limestone or in chalk, in fact flow more under than overground.

Yes, it's true. Some rivers of my acquaintance do flow more under than overground.

[Boreades]

Addendum.

TME regulars might recall a previous discussion on the "strangeness" of all the rainfall over the entirety of the Thames Basin having to flow over one weir. I pointed out at the time, and would remind folk, that a lot of the rainfall over the entirety of the Thames Basin falls onto chalk downs. In which situ, the rain tends to go straight down underground, and not a lot runs off in the "normal" manner i.e. surface rivers and streams.

At Château Boreades, we did in fact have one learned visitor who was writing a PhD thesis (related to chalkology) that some of the rain that fell on the plains/chalk downs of Southern England will resurface many years later in France. Care of the chalk layers that act as a huge capilliary wick, transporting fresh water underneath the English Channel.

If it's true, I'm glad to have made a small but unwitting part to the success of the French wine industry.

Cheers! Whose round is it?

[hvered]

Some rivers of my acquaintance do flow more under than overground.

Mine too, though I've not come across a river quite like the Unica. Not in chalk-land anyway.

In chalk downland many (all?) streams are seasonal, some completely dry for years, and unreliable for both fishing and drinking so would have to be canalised or redirected perhaps.

[hvered]

Canterbury was once accessible by sea via the Wantsum Channel (formed by the rivers Wantsum and Stour). Was the channel that separated Thanet from the rest of Kent a man-made one?

It might be worth looking at the Kennet watercourse south of the Ridgeway at Mildenhall, or Cunetio as the Romans called it, for signs of messing about with the river. There is a Mildenhall south-west of Grime's Graves which are just north of the Ridgeway/ Icknield Way on the Suffolk/Norfolk border.