A stitch of around 10 vertical shots, pulled about in PTGui and blended again with Enblend. Each shot was at 90mm and f8, locking the exposure on a green bit. I added some grads later, dodging and burning to try and bring out a bit of depth and texture in the mid-ground.
My "base" image, after PTGui, was a tif of 612MB: pixel dimensions of the original are 17,612 x 4559; it took my pc 45 minutes to create the basic pano...a mere blink of an eye to some of the experts who work in the giga-pixels.