Tephric material (WRB)
From Wicri Urban Soils
Tephric material is one of the diagnostic materials used, in the WRB system, to discriminate some soils from others.
Contents
Description
Tephric material[1](from Greek tephra, pile ash) consists either of tephra, i.e. unconsolidated, non- or only slightly weathered pyroclastic products of volcanic eruptions (including ash, cinders, lapilli, pumice, pumice-like vesicular pyroclastics, blocks and volcanic bombs), or of tephric deposits, i.e. tephra that has been reworked and mixed with material from other sources. This includes tephric loess, tephric blown sand and volcanogenic alluvium.
Diagnostic criteria
Tephric material has :
- 30 percent or more (by grain count) volcanic glass, glassy aggregates and other glass-coated primary minerals in the fraction between 0.02–2 mm
and :
Relationships with some diagnostic properties
Progressive weathering of tephric material will develop vitric properties; it is then no longer regarded as tephric material.
RSG in which tephric material can be observed
See also
- The FAO reference text, (2007 version)
Notes
- ↑ Description and diagnostic criteria are adapted from Hewitt (1992)
