A further 15 minutes or so walking will bring you to a sharp 90 degree turn to the right. You are now entering the deepest part of the gully, known to the troops in 1915 as ‘The Zig Zag’. This section of the gully is a series of dog-legs, and in my view it is a strange and oppressive place to walk through.T he walls are extremely steep, especially on the right, the Fir Tree Spur side. There was a goat path on this wall, widened and developed by engineers, which was used to ascend to the trenches above. Its winding nature was another reason for the ‘Zig Zag’ epithet. There is now no trace of this.
In the picture above, taken during my walk through in 2015, the view looks back on the sheer wall that once carried the path up to the lines. The position is very close to the 1915 image below, (Public domain, Wiki Commons).
Recently added, also below, is a short video of my September 2015 walk through the Zig Zag.