Geograph - photograph every grid square

Re the navigation bank, southern part, Birkenshaw
The writer questions whether the purpose and wonders if it was used for water catchment or to take slag back to the Blue Hills. I have a book the history of 30 villages 1905 published by James Parker of Great Horton in which he describes how the coal and ironstone for the works were 'got at a place owned by Emmet, Holden and Bolland , called "Blue Hills" and was conveyed to the foundry by means of a narrow canal,which they made from the Blue hills Ironstone and Coal pits. It was conveyed by horses in barges, and the ancient line of the canal can be traced today.'