Tag: river

A New Port

Yarm was a route centre with tracks and roads coming in from all directions to cross the River Tees.  Later the railway also passed through the town, with an impressive viaduct carrying it above the houses and across the river, beside the road bridge.

With lots of routes to different places for trade, it is not surprising that Yarm was once a thriving port.

But here’s the River Tees at Yarm.  Do you see the problem?

The river is sizeable but way too small to accommodate the large ocean going ships we use today.  Even in its heyday, the rise and fall of the tide and the meandering nature of the river made it a hazardous journey in from the sea.

When new port facilities were built downstream at Stockton and Middlesbrough, most river traffic soon stopped coming to Yarm.

Today Teesport is almost within sight of the open sea.  Yet it is still a couple of miles into the river estuary to benefit from the sheltered water.  The surrounding land is covered in industries and the river provides a transport route to bring in raw materials and export products.

Have a look at the satellite view here.  Spot the jetties, note the industries and follow the river down to the sea and then back inland to Yarm.

Add Stockton, Middlesbrough and Teesport to your map from An Inland Port.

Side Slope Slide

The stones carried by a river are dragged along on the river bed causing abrasion.  The river bed is smoothed and worn away producing potholes.

This means that the channel gets deeper.

So why doesn’t every river have deep vertical sides like this?

The steeper the slope the more likely it is that the soil and rocks will fall.

They will land in the river and the river will break up the big pieces and gradually wash everything away.

But slopes don’t have to be vertical for soil to find its way into the river.

Here you can see how the layer of soil and plants is gradually sliding down the hill, leaving bare areas where the ground has slipped away.

The result is that the valley usually takes a V shape.  The river is deepening in the middle and the side slope slide determines the angle of the V.

It could be quite narrow like this…

…or wider like this.

Next week we will look at a situation where you will find some vertical slopes.

Managing the Flow

The Thames and Severn Canal entered the River Thames just west of the town of Lechlade from where boats could use the river to make their way to London.

The main water supply for the canal was taken from the River Churn, with the pump at the Thames source providing extra supply in the summer. The Churn joins the Thames at Cricklade. (If you’ve signed up, there will be a map in your inbox, that shows how all this fits together.)

So at Cricklade there was less water coming down the Thames, as the spring was drying up, and less water coming down the Churn as it was being pumped into the top section of the canal, not all of which would find its way back to the Thames.

At Lechlade some water would come in from the canal, but not as much as had been put into the canal originally.

Lower river levels made it hard for boats to get through and during periods of low rainfall it was even more difficult.

When the river was low more water was taken from the ground, which meant that more springs dried up and the river got even lower. In the end there is only a certain amount of water available.

The Thames and Severn Canal closed in 1933. The railway was now used to carry goods to and from London, whereas the canal needed repair and the water shortage was a major problem.

The Thames is still used by boats as far as Lechlade but most of them are carrying holidaymakers.


There are 45 locks enabling boats to safely pass the changes in level of the river.


Many of these have a lock keeper, part of whose job is to monitor the flow of the river. Too much water can lead to flooding. Too little causes problems for boats. At each lock the water that is not needed for the lock passes over a weir. The lock keeper can control how much water is allowed over the weir to maintain the correct water level upstream of his lock.


Quite a spectacular amount of water by the time you get further downstream.

Join me next week for a look at how the power of the water is being used.

Control of the Tees

Yarm is on the south bank of the River Tees, at the point where the river makes a huge meandering loop.  The oldest part of the town is surrounded by the river on 3 sides, which made the site easy to defend.

Before 1995, when a barrage was built further downstream, the River Tees was tidal all the way inland to Yarm.  There were no barriers to stop boats reaching Yarm from the sea.

Until 1771, Yarm was also the lowest bridging point on the River Tees.  In other words, if you were walking along the coast, when you got to the Tees you would have to follow the river inland all the way to Yarm before you would find a bridge to cross it.

The bridge was, and still is, halfway round the river meander, at the northern side of Yarm.  Crossing from the north you are immediately into the High Street, which is wide allowing space for a market.

So, a thriving market town, at a point where roads and tracks from all directions converged to cross the river.  Plenty of opportunities to trade and send goods to other places along the roads and tracks.  Definitely a good location to dock a boat.

The wharves for the boats to dock were just downstream from the bridge.

Today they are building new houses on the site.

What happened to the port?  We’ll find out next week.

To get the map that goes with this post, fill out the form in the sidebar selecting “Geography Worksheets”.

Potholes

We saw last time that as the river moves the pebbles around, they crash into each other and bits break off.  The pebbles become smaller, smoother and more rounded by this process, which is called attrition.

In some places the river drags its pebbles across solid rock on the river bed.  This rubs both the pebbles and the river bed, gradually smoothing the surfaces.  The process is called abrasion.

If the pebbles get trapped into a swirl by the current, then they whirl in a circle and the abrasion makes a depression in the river bed.

The circular depression is called a pothole.

Once the pothole shape has started to form, pebbles will tend to collect in it.  They will sit there in position, all ready to be whirled round when the river flow is strong enough.

So, the pothole will quickly get deeper, which means it will collect even more pebbles etc.

Abrasion on the river bed will make the river channel deeper and will cut a deeper valley through the landscape.