• 06.041 that here stood right up the mountain slope
• 18.021 from the mountain-slopes,

“Mountain slope” with or without hyphens is found in OED.  I have added the spaced version of the signifier to our own entry.

“mountain, n. and adj.” OED Online, Oxford University Press, June 2017, http://www.oed.com/view/Entry/122893. Accessed 19 September 2017.