Definition of "concealing"

Standing half-befogged upon the mountain of his Fate, all that part of the wide panorama was wrapped in clouds to him; but anon those concealings slid aside, or rather, a quick rent was made in them; […]

1852 July, Herman Melville, “Book V. Misgivings and Preparatives.”, in Pierre: Or, The Ambiguities, New York, N.Y.: Harper & Brothers, […], section V, page 142