The skirt becomes pants when the flap on the front is folded over and buttoned on the right side. The wide legs give the look of a skit when the wearer was in the saddle. In one of the seams you can see paper used by the maker of the skirt. The last picture is from the library of congress dated 1911 and shows a similar skirt.
In doing research, the only other one i found was in a museum. This item is made of cotton.