In the 2nd half of the 3rd century AD fashion went somewhat wild when it came to soleae. The small toe area gets extremely exaggerated, the sole shape becoming almost triangular. Here is a reproduction of a find from London showing one extreme of that fashion development. The sole consists of only one layer except for the heel area, which is strengthened by a second layer and edge nailing. The upper side is decorated by tooling. This type of sandal continued to be in use well into the 4th century.
If you are curious to see what I am working on at the moment, please go to my Res Rarae Facebook page.