This is a very interesting, manufactured, toe-clipped shoe! I've seen another that is similar but I think this one adds a new trick or two.
I believe the fullering is filled with a rope material. Perhaps to combine the benefits of traction plus concussion reduction. The farrier 'sprinkled' a coating of traction material (borium?) over the rope.
The heels are onioned and hollowed out to make containment space for additional packing material. The packing looks like it may have been molten tar (like blacktop tar?) that is poured into the hollows of the heel.
There are small pins thru the shoe at the web edges that appear to have been installed to hold the molten tar packing in place once the tar cooled into a solid consistency.
Some of the design aspects remind me a bit of the new EDSS PLR shoe. Dropped breakover on the sides with recessed nailing, wider heels. Of course, minus the squared up toes.
This shoe is marked "Patent June 1898". on the inside of the lateral web.