The ironstone bed in the Corby area ranged from 4ft to 11 ft thick with an average of 7.25 ft. The bed outcropped at the top of the escarpment and then was to be found under increasing cover to the east. Whilst early workings were carried out by hand the exhaustion of the shallow deposits required the use of machines to remove the covering material or overburden. In the Corby area the overburden depth varied from 3 ft to 104 ft in depth. The overburden in some quarries contained beds of limestone which were loosed by drilling and blasting prior to removal. The Ironstone beds were also loosed by drilling and blasting using ammonium nitrate explosives to enable the face shovels to pick up the fragmented rock for loading into railway wagons.
An early photograph of Lloyds Ironstone Co. No.2 Wilson Long Jib stripping shovel moving overburden with No.4 Wilson steam shovel loading train at quarry face Courtesy G Evans Collection
Lloyds Ironstone pioneered the use of machines in quarrying and in 1899 the first long jib steam stripping shovel in the world was put to work moving overburden, which hitherto had been removed by hand. This innovation greatly extended the land on which ironstone could be practically worked.
As the quarries extended to the east deeper and deeper overburden was encountered requiring the use of larger and larger stripping shovels. a 190-ton Bucyrus 175B steam stripping shovel was purchased in 1917 whilst in 1923 an even larger 400-ton Ruston No. 250 steam stripping shovel was purchased for use at Deene Quarry, Corby.
The Ruston 250 steam stripping shovel digging overburden in Deene Quarry, Corby
In 1934 Stewarts and Lloyds took delivery of the first Ransomes and Rapier Type 5360 quarry stripping shovels. These huge 650 ton electrically powered monsters were used to strip the increasing depth of overburden to access more ironstone reserves. Fitted with jibs approximately 100 feet in length these impressive machines could strip and dispose of the overburden in one operation down to a depth of 55ft, moving about 12 tons at a “bite”.
The giant Ransomes and Rapier built Type 5360 stripping shovel digging overburden Courtesy G Evans Collection
Five similar machines were delivered over the next few years and put to work at the ironstone quarries at Short Leys, Deene, Stanion Lane, Cowthick, Priors Hall and Brookfield. In the quarries the 5360’s removed the overburden generally with a Ruston Bucyrus 100 RB electric mining shovel loading the quarry trains with ironstone destined for the steel works. Ten 100RB shovels were distributed within the ironstone quarries at Corby. Where the depth of the overburden was just too deep for the 5360 to fully clear some quarries (notably Deene, Short Leys and Priors Hall) employed an excavator (usually a 100RB) to dig the surface down to a level at which the 5360 can take over. This practise was known as top stripping and small locos and dumpcars were used to take the dug overburden away to tip.
A view of a R& R 5360 working together a 100 RB face shovel at Short Leys Quarry Corby. The 5360 could not remove all of the overburden and initial removal of the upper layer (top stripping) is shown in the distance BSC
