What is this piece of architecture?

This is on the side of the river Wear near where the Wearmouth pit used to be. A local historian suggested it might be something to do with loading boats or barges with coal, but he didn't really know. I have included my friend in the picture so you can see the scale. It's massive. Weirdfish just told me what it is.

This coal staithe was built in c1900. It would once have supported railway lines from which coal wagons could tip coal directly into ships' holds. This is the last surviving coal staithe on the Wear. Once each bank was lined by staithes from which the many local collieries loaded ships. You can read more about it on the link he gives below if you are interested.
More info.
Before 1750 coal was loaded on to collier boats by keelmen who had small boats with a shallow draught, that took the coal from the shallow river to the sea.  About 1750 a new development began to be used on the Tyne. New pits were being sunk further and further away from the river and coal was being brought to the riverbank via wagon ways. Once there, in places accessible by colliers, coal staithes were built to allow coal to be dropped directly into the holds of the colliers without the need for keels. The staithes were short piers that projected out over the river and allowed coal wagons to run on rails to the end. Colliers would moor alongside the end of the staithes and, initially, the coal from the wagons was emptied down chutes into the colliers’ holds. Later, to avoid breakage of the coal, the coal wagons were lowered onto the decks of the colliers and were unloaded there. This was the beginning of the end for the keelmen and they realised the threat that the coal staithes posed. Strikes and riots resulted whenever new staithes were opened. In 1794 the Tyneside keelmen went on strike against the use of staithes for loading coal.[1]
Because of the shallowness of the Tyne, the use of coal staithes did not entirely obviate the need for keels. The amount that the staithes projected into the river was limited so as not to obstruct river traffic, so that the staithes ended in shallow water. As colliers were loaded their draught would deepen until often they were no longer able to continue loading from the staithes. In such cases the colliers would have to move into deeper water and the loading would be completed using keels.[2]
 In 1800, the Wear, employed 520 keels ( a keel is the name of the small boat). Coal staithes were not introduced on the Wear until 1812, but were resisted just as strongly by the keelmen there. They rioted in 1815 in protest at coal being loaded via coal staithes. Information from Wikipedia.