• 11.014 and they turned into a little steep-walled bay,

Not found in OED, although ‘steep-sided’ is.

• 08.106 as he danced on the spider-string

This word does not appear in OED.

• 08.102 only great strands of double-thick spider-rope

This word is not found in OED.

• 08.107 and ill from spider-poison,

This word does not appear in OED.

• 08.093 in the spider-colony,

This word does not appear in  OED.

Just one of the quick visual images that allows us to draw maps or illustrations in our imaginations.  The clarity of Tolkien’s landscape contributes to the depth and “consistency of reality” of his world.

• 13.065 and the great shoulder of the south-pointing mountain-spur

this word is not found in OED.

• 12.101 the snail-covered walls,

Not found in OED.

• 12.007 straight as a ruler, smooth-floored and smooth-sided,

Not found in OED.

• 12.007 straight as a ruler, smooth-floored and smooth-sided,

Not found in OED.

• 13.037 It was of silver-steel,

…which the Elves call mithril.

I am fascinated to learn that silver steel has its own, albeit unhyphenated, sub-entry.

silver steel  n. a fine steel containing a small amount of silver.

1831   J. Holland Treat. Manuf. Metal I. 248   Silver steel, having the advantage of euphony.., becomes a popular denomination in the market.

“silver, n. and adj.” OED Online, Oxford University Press, June 2017, http://www.oed.com/view/Entry/179788. Accessed 21 September 2017.