it was during an expedition to the jura mountains , an area rich in colitic limestone , that jonquil jabot underwent her life-changing experience , a terrifying encounter with a jacob 's sheep whose fleece had become entangled on the prickles of a juniper bush , driving it to such a frenzy of angry frustration that , on its release from the bush by means of jonquil jabot 's careful application of a pair of nail scissors , it flung itself from the mountain with a `` baaaa '' of despair and burst with a `` pop '' on the black rocks beneath .