The flame line shows the Lewis Glacier's location in 1934. The glacier has since receded about 275m. In 1934 it carried on almost to the top of the peak on the right and covered the left side of the picture as high as the break in the scree slope, just below the vertical 'wall' that leads to the summit.

One of the best shows I had of this work was at the Kunst Haus in Vienna in 2015, a building designed by the early environmental activist and artist Friedensreich

. I even got to stay in his highly idiosyncratic apartment.