The original shot with the camera exposure made for the background. The foreground is completely dark and has several stops, less light, on it.

This shot includes both the original shot and the new shot where I made the exposure for the foreground. I merged the two and masked out the background, which was extremely overexposed.

The palette above shows the close-up rock used to fill in the foreground, but I don't like the blasting light caused from a flash. It washes out the detail in the surface of most objects.

A curves adjustment layer is added to both layers as well as a mask on the close-up layer.