It is battleship linoleum, used on naval ships due to it durability. The original poster was in the 1948 category, I have a 1958 Suburban, and Hambone has a 1962, so we know it was used for many years.
I am going to go out back to my barn tomorrow and see if I can find that contour gage and, if nothing else, take a picture of the contours on top of a fine metal scale.
Regards, Mark
