There were two large rock shelters.. I don't recall seeing the huge cairn in that photo you took. Perhaps it was made into one of these shelters..? Possible too that I missed it--don't pay much attention to cairns in this weather.
"As an adolescent I aspired to lasting fame, I craved factual certainty, and I thirsted for a meaningful vision of human life - so I became a scientist. This is like becoming an archbishop so you can meet girls."