Roark’s words were like the steps of a man walking a tightwire, slow, strained, groping for the only right spot, quivering over an abyss, but precise.
Wynand thought that what he felt was curiosity—if curiosity could be blown into the dimensions of a thing from the abyss—like those drawings of beetles the size of a house advancing upon human figures in the pages of the Banner’s Sunday supplement—curiosity, because Ellsworth Toohey was still in the building, because Toohey had gained admittance past the orders given, and because Toohey was laughing.
There are no more uses of "abyss" in the book.
Show samples from other sources
These were men who had built up wealth and social status over long careers and now found themselves looking into the abyss. [of the 1987 stock market crash]
Alan Greenspan -- The Age of Turbulence
The nerve-grinding squeal of the spike cutting through the ground sent a shiver up Thomas’s spine, though a second later the Griever tumbled into the abyss.