This has been driving me nuts for the past month as I first thought it was something that I had done wrong.
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I first thought I screwed up the distribution of one of the snow sublayers resulting in these white peaks, although it didn't quite make sense. It happened with both Lucio's embossed snow and cbalaskas' ice and snow.
I finally scrapped everything and started from scratch with just a powder snow layer using fake stones.
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...and this time it extends beyond the snow onto a piece of terrain with no additional shaders.
I've disabled just about everything after this (fill lights, shaders with translucency/transparency, GI, fractal detail ON or OFF) and it's still there so it seems to be terrain related.
TGD with TER:
http://www.path.unimelb.edu.au/~bernardk/tgdemo/lighting_problem.zip (5.3Mb)