The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.
the valley of a stream of the third order (a tributary of a river’s tributary), flowing in a direction opposite to that of the dip of the strata and flow of the main river.
The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.