Irstead Underwater Obstruction

[Bob48]

can anybody give me some more info about this polease

[BroadAmbition]

Yep - It's called the river bed or in that particular spot - Shoals

Griff

[JennyMorgan]

Best not go swimming there, shoals can be very contagious, especially in the nether regions.

[Bob48]

thanks lol i wouldn't want to get infected with " River bottom "

[JennyMorgan]

Being near to Gt Yarmouth and the sea means that there is also a very real risk of catching crabs 

[Bob48]

1 minute ago, JennyMorgan said:

Being near to Gt Yarmouth and the sea means that there is also a very real risk of catching crabs 

you'd not want to catch a crab in an eight , it hurts too much

[JennyMorgan]

1 hour ago, Bob48 said:

you'd not want to catch a crab in an eight , it hurts too much

Is that in a rowing eight? Those sliding seats can be really painful!

[RumPunch]

I'd been going over Irstead Shoals for around 10 years before I walloped the bottom really quite hard, so it took me by surprise.

Going down river ( from Barton ) about a couple of houses short of the moorings

I draw 1 metre, bilge keeled yacht.

 

[Springsong]

I never caught nuffink at Irstead when swimming.

[Bob48]

10 hours ago, JennyMorgan said:

Is that in a rowing eight? Those sliding seats can be really painful!

My wife used to row for our city club , she caught a " crab " nearly took her out of the boat . 

 

[ChrisB]

Maybe they hit a bit of hard stuff when they were digging it out.  Barton was dug in the Middle ages but the Ant passed to the East. The river was diverted in the 1700s (I think) to provide navigation along with Paddys and Lime Kiln. I think the original river was about Mud Point. So those Shoals are actually the bottom of a canal. Don't suppose the residents would like it named "The Cut"

[teadaemon]

I admit I may be wrong, but I believe the shoals at Irstead are a continuation of the underwater gravel spit that runs across Hickling Broad, and are presumably the remains of a long-gone river bed running roughly perpendicular to the current channel. I've never run aground on them, but having quanted up that stretch of the Ant a number of times in my youth, it's very obvious when you're going over them, due to the sound transferred up the pole and the very different feel of gravel to the usual mud.

[Vaughan]

I reckon it was a Roman road. TIMBO? Where are you??

Seriously though, it is a strange feature and it would be interesting to know more about it.

[LondonRascal]

I remember reading about the Broads Authority's plan for this stretch - it was a long report, it must have taken a number of people a rather long time to prepare and was looking likely that the Broads Authority would have to actually spend money and dredge the area when someone discovered that if they did and made the area deeper it would not just be the removal of natural sediment but it would actually be causing the river to be made artificially deeper.  In short it would fall outside of their normal dredging program and cost more money.

So they cut back the trees, put up two large signs to tell boaters to go slow and not cause any wash and warn them of a narrow channel.

When I cruise through this section on B.A and we have our sonar on, it does noticeable decrease in depth and you see the profile of the river bed change.  This also occurs when passing Stokesby Ferry. I can't remember what the  depth is off the top of my head, but I guess it is something that does not affect too many boats but the odd sailing boat with a deeper draft do seem to suffer somewhat.  I wonder if this is a newer issue - perhaps where there is 'ground heave' whereby the river bed is rising up in the centre of the channel and subsiding towards the edges?

[JennyMorgan]

Interesting comment is that, Robin. Firstly the BA has spent a small fortune in researching reasons for not dredging and secondly some of these shallows were historically cattle walks and indeed the walks were indeed often natural outcrops built up to create fording points as part of long distance droves. The footpath that goes outside my house is very clearly enroute between Burgh Castle and Colchester and a gravel ridge does pass under Oulton Broad in such a way that it must surely have been a part of that same route. 

[Timbo]

4 hours ago, Vaughan said:

reckon it was a Roman road. TIMBO? Where are you??

I'll give you Roman road young man! 

I will drag some more map data out later but I think the OS map below will make things a little clearer. The parish boundary (the dotted line) shows the path of the old river which followed the eastern edge of Barton Broad, ducks out to Middle Marsh Drainage Mill and then out to Mud Point. Parish boundaries would often use rivers as the divide.  From Mud Point north to the opening of the Ant into the Broad is a canalised structure. 

JM is right. The name Irstead Holmes is the real clue as to what's going on here. A Holme is a deposit of sand and gravel left as a glacial deposit. Irstead Holmes is part of the same geological structure as Heigham Holmes. To the right of the opening of the Broad on Great Fen, the 1890's Bartholomews Maps show the remains of sand and gravel extraction in this area.

If you look at the road running into Irstead you will see that it follows the natural ridge of sand and gravel until it reaches the new 'cut'. I suspect a little bit of 'field and marsh walking'  will pick out a much older route that continues along this ridge across to Hickling. The mapping certainly shows existing modern routes following the contours of the Holme.

I can't remember which book...but one early 19th century guide to Broads Boating makes mention of The Shoals as a favoured place for ladies and gentlemen to tie up their craft to make use of the sand bar as a location to bathe with a mud free 'bottom'. I'm hoping they were referring to the river...not their own! 

[Vaughan]

Fascinating, thank you.

No matter how much we think we know about the Broads, there is always more to learn.

[Timbo]

Here you go guys...the 1909 Bartholomew Map from the Scottish National Library.

That sure is a large regular shaped expanse of water on Great Fen!

[Bob48]

following on from the discussion about river bottoms and local features , can somebody enlighten me as to how " The Heater " at the northern (?) end of Barton Broad got its' name please .

[stumpy]

I was told it referred to the triangular shape of the island looking like an old style flat-iron heated on a stove top. The island at the Sutton/Stalham split has been referred to as the Heater too.

 

[grendel]

heater was the name for a knights shield of the same shape as a flat iron, so this may be where it originates.

[Springsong]

I dont fully understand all this squit about dredging it never seemed to be a problem years ago. These both taken taken from Shoals cottage Irstead . The first one looking up stream and the second looking downstream.

Both taken in the 1950s.

Edited May 5, 2017 by Springsong
If you look to the extreme right on the first photo the dredgings will be from more or less opposite the staithe

[ChrisB]

In the States a triangle at a road junction is called a "Heater"

[grendel]

https://en.wikipedia.org/wiki/Heater_shield