It was of turf and moss.

It did not seem to promise well for getting into the sky, but Diamond had learned to look through the look of things.

The voice must have meant that he was to go down this stair; and down this stair Diamond went, without waiting to think more about it.
It was such a nice stair, so cool and soft--all the sides as well as the steps grown with moss and grass and ferns! Down and down Diamond went--a long way, until at last he heard the gurgling and splashing of a little stream; nor had he gone much farther before he met it--yes, met it coming up the stairs to meet him, running up just as naturally as if it had been doing the other thing.

Neither was Diamond in the least surprised to see it pitching itself from one step to another as it climbed towards him: he never thought it was odd--and no more it was, there.

It would have been odd here.