Iron smelting

Saxo-medieval iron pits archaeology

Dotted around the property you will see shallow, roughly circular, pits. They are mostly from two to eight metres wide and up to a metre deep. At one time the pits were thought to be prehistoric dwellings. However, excavation in 1964 provided evidence that the pits were dug to obtain iron ore. Fragments of Thetford Ware pottery discovered during the dig were dated to the late Saxon period-c 850 -1150 AD.

One of the best places to see these pits is in front of the seats just north of the car park. There are also some large pits in the woods on the right as you enter the property. Another group of pits can be found to the west, along the main path and near to the privately owned Heath Cottage. These latter pits are partly on land owned by the National Trust and partly in the grounds of the cottage. But there are several more areas of pits on the property all of which occupy the high areas of the ridge. 
The pits are all to be found at the top of the glacial ridge and spread only a little way down the hillside. No pits can be found on the lower slopes or on the flatter ground to the north.
Nodules of iron were dug from the glacial sand.
Archaeologic investigations found some pits had traces of charcoal. Lumps of slag were found near by. It is assumed that these were sites where the iron ore was smelted, using the wind blowing over the hilltop to help get the charcoal in the furnaces up to the necessary temperature. 


Shrieking pits


These pits were once sometimes called shrieking pits. No one really knows how they got this name.
Some think it is because the wind made a noise when blowing over the tops of the pits. Rather like the noise made by blowing across the top of a bottle.

In the past there were many fewer trees and so one can well imagine the wind blowing over the pits.
Or maybe the sound was just owls hooting, as they do today.

There are many similar pits to be found around Aylmerton, a village very close the property. One particular pit near Aylmerton Church is also known as a shrieking pit but in this case legend has it that the name came from the shrieks of a woman whose child was murdered and then buried in the pit.


Producing the iron in medieval times


The layer of iron pan produced the iron ore, present in the form of nodules. Iron pan is a layer of soil cemented by iron oxide. The nodules were found less than 2’ from the surface and would have been roasted before smelting. Smelting involves heating up iron ore until the metal becomes spongy and the chemical compounds in the ore begin to break down.

 
Perhaps 150 tons of iron could have been obtained over the years for use locally.  
As well as being traded in the form of bars, iron would have been used locally by blacksmiths mainly for agriculture uses, such the tips of ploughs, wheel rims and various hand tools. What it was used for would depend on the local blacksmithing skills.

Traces you may come across


You may come across lumps of slag remaining after the iron ore has been smelted.
You can see the iron slag left over from the smelting process in many places, including the cairn to the right of the main path, about 50 yards west of the car park. Some local churches have the iron pan in their walls.

You may come across lumps of slag remaining after the iron ore has been smelted
Iron ore and slag
You may come across lumps of slag remaining after the iron ore has been smelted