When this happens, the pumice lapilli commonly flatten, and these appear on rock surfaces as dark lens shapes, known as fiamme.
42.
Some fiamme represent fragments of volcanic ejecta, often pumice lapilli that have been flattened by compaction and / or rheomorphic peralkaline tuffs ).
43.
There are two types of rock associated with the basalt, lithic lapilli-tuff ( well-worn, consolidated volcanic ash ).
44.
Pyroclastic fall deposits, composed of lapilli, were erupted from volcanoes in the Pemberton Belt and are overlain by subsequent basaltic lava flows.
45.
Strictly speaking, if the rock contains scattered pea-sized fragments or fiamme in it, it is called a welded lapilli-tuff.
46.
Its tuff ring, created by many explosive eruptions, is made of a mixture of volcanic ash, lapilli and fragmented sandstone country rock.
47.
Ignimbrites are made of a very poorly sorted mixture of volcanic ash ( or tuff when lithified ) and pumice lapilli, commonly with scattered lithic fragments.
48.
In each of these formational phases, lapilli fallout ( resulted from Plinian eruptions ) and the pyroclastic flow deposits were transformed into ignimbrites, from melting.
49.
The cones are constructed by reddish lapilli and lava bombs up to wide with subordinate amounts of ash-like material, concentrated in the Hawaiian episodes.
50.
Welded tuffs ( and welded lapilli-tuffs ) can be of fallout origin, or deposited from pyroclastic density currents, as in the case of ignimbrites.
