Hilary Tann, professor of music, was invited to the University of Wisconsin-River Falls on May 14 for a concert devoted entirely to her music. “The Power of Nature: Music of Hilary Tann” included two choral works, three chamber pieces, and three works for full orchestra. The final work in the program was the premiere of “Sarsen,” written last fall and jointly commissioned by the St. Croix Valley Symphony Orchestra and the Saratoga Springs Youth Orchestra. The local premiere was May 5. Each of the three movements refer to different standing stones: an erratic in the Adirondacks, the Bat Stone from the Garden of the Master of the nets in Suzhou, China, and one of the Kennett Avenue stones from the ancient stone circle in Avebury, England.