As a bonus image, I’m including a little bit of blue. Like all of my under-glacier images, the light is dim and the location is long gone.
I’m standing in the stream which has cut its way under the ice. The ground is gravel over bedrock, and the deeper one goes the thicker the layer of gravel is. By this point, the gravel is thick enough so the stream is completely contained in the gaps between the stones. The running water carries heat under the ice which creates a gap. Then warm air start to move through and widen the gaps. The color variation in the ceiling is from the variation in thickness and sand content.
I’ve tried several times to try to duplicate this image by print and by film. In call cases, the color reproduction has stymied me. The colors reproduced by the film are not easily obtainable in any of the ink or film-recorder color spaces I’ve tried. I’ll try again in a few more years. Until then, please enjoy this original with all of its subtle colors.