The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.
a tuffaceous volcanic rock consisting of lava, ash, and fragments of glass. Tufflavas are intermediate in structure and method of formation between lavas and tuffs. Ignimbrite is a variety of tufflava.
The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.