Cryoturbation (USDA Soil Taxonomy, 13th edition)
Source:R/diagnostics-conditions-usda.R
cryoturbation_usda.Rd"Cryoturbation (frost churning) is the mixing of the soil matrix within the pedon that results in irregular or broken horizons, involutions, accumulation of organic matter on the permafrost table, oriented rock fragments, and silt caps on rock fragments." – KST 13ed, Ch 3, p 43.
Arguments
- pedon
A
PedonRecord.
Details
Diagnostic for the Turbels suborder of Gelisols.
Implementation (v0.8.x): Uses heuristics from horizon designations and morphology data:
Designation contains 'jj' (cryoturbation symbol) per KST notation;
OR boundary_topography in {"irregular", "broken", "involuted"};
OR coarse_fragments_pct varying non-monotonically with depth (proxy for "oriented rock fragments");
OR designation contains 'f' (frozen) AND irregular boundary_distinctness.
Refinement to incorporate explicit cryoturbation_evidence
column is deferred to v0.9.