On the lower foreground there's the Pra Sec glacier snout - this was the last glacier of the range to have been explored by humans - only in 1970! The spur on the left comes down from the lonely Aiguilles De Pra Sec, seldom visited rocky spires made of very sound material.
It's difficult to visualize how huge this "thing" is. From the place where the picture was taken to the summit, the vertical distance is almost 2800m, while the horizontal distance is less than two kms. From the top of the glacier, the Tronchey wall proper is 1350m tall, 150m. higher than the famous north face (see this picture for a comparison), but from the place where the picture was taken to the bottom of the wall, the height gain is even higher - almost one mile. On the upper right you may see the towers of the Tronchey ridge - the exposure there is so mind-numbing that completely loses any meaning.
Immense, devastating avalanches come down periodically from this face to the valley floor, often, in particularly snowy years, strong enough to climb the opposite side of the valley. The "cone" below this wall (and between the two hamlets of Pra Sec and Tronchey) is understandably completely devoid of any tree.
(Picture courtesy of www.bicio.info>)