In prehistoric art, finger flutings are lines that fingers leave on a soft surface. Considered a form of cave painting, they occur in caves at least through southern Australia, New Guinea, and southwestern Europe, and were presumably made over a considerable time span including some or all of the Upper Paleolithic. Most are not obvious figures or symbols but, rather, appear to many observers as enigmatic lines. They are also called tracés digitaux or finger tracings and (though these terms are also in part interpretative) meanders, macaroni, and serpentines. The term finger fluting was coined by Robert Bednarik.
Generally they are made in a substance called moonmilk.More on moonmilk here (I find it fascinating.)
