I was initially attracted to the rock in the mid-ground - with it's graphic-angular shape and directional lighting. But it was only while setting the camera up on my tripod that I noticed the lower darker rocks. I felt these could be a great foreground detail with their mottled texture. Often black rocks turn to a muddy mess in a scene, but when there is back lit directional light shining on them, it can help lift their tonal values from extreme black, into the lower mid-grey tones. Making it easier for me to record them on Fuji Velvia.
I made this image on my Mamiya 7 camera. I'm aware that I'm a landscape photographer who feels more at home with portrait-orientated compositions. Perhaps it's the ability to mix a lot of sky in with a lot of foreground that works for my eye. I'm really not sure, but having a mix of aspect ratios to work with has really helped me open up my eyes to the surrounding landscape and consider where each object should be placed.