Ignimbrites are made of a very poorly sorted mixture of volcanic ash ( or tuff when lithified ) and pumice lapilli, commonly with scattered lithic fragments.
12.
In general, the most contentious item counted is chert, which is usually counted as a lithic fragment, but is sometimes better suited in the Q pole.
13.
Vitric ash particles from high-viscosity magma eruptions are typically angular, vesicular pumiceous fragments or thin vesicle-wall fragments while lithic fragments in volcanic ash are typically equant, or angular to subrounded.
14.
A particularly troubling paradox was the occurrence of blueschist blocks ( low temperature and high pressure metamorphic rocks ) in direct contact with graywacke ( a coarse sandstone with lithic fragments ) that was deposited in a sedimentary environment.
15.
"' Lithic summary : "'175 Lithic fragments were recovered and were classified as follows : 92 are considered as artifact fragments, 77 waste or chips, 4 core residues, 2 green stone residues.
16.
The sand-and gravel-sized fraction of the diamictites consist of volcanic, granitic and metasedimentary lithic fragments that have the same composition as the sediments of the Brookline and Dorchester members . chattermarked quartz grains and dropstones have been reported from these diamictites.
