Table 7.5.

Example of facies classification terms

CodeLithofaciesSedimentary structures
GmsMassive matrix supported gravelNone
GmMassive or crudely bedded gravelHorizontal bedding, imbrication
GtGravel, stratifiedTrough cross-beds
GpGravel, stratifiedPlanar crossb-eds
StSand, medium to coarse, may be pebblySolitary (theta) or grouped (pi) trough cross-beds
SpSand, medium to coarse, may be pebblySolitary (alpha) or grouped (omicron) trough cross-beds
SrSand, very fine to coarseRipple marks of all types
ShSand, very fine to very coarse, may be pebblyHorizontal lamination, parting or streaming lineation
SlSand, fineLow-angle (10°) cross-beds
SeErosional scours with intraclastsCrude cross-bedding
SsSand, fine to coarse, may be pebblyBroad shallow scours including eta cross-stratification
Ssc, Shc, SpeSandAnalogous to Ss, Sh, Sp
FlSand, silt, mudFine lamination, very small ripples
FscSilt, mudLaminated to massive
FcfMudMassive with freshwater molluscs
FmMud, siltMassive, desiccation tracks
FrSilt, mudRootlet traces
CCoal, carbonaceous mudPlants, mud films
PCarbonatePedogenic features
DmmMatrix supported, massiveStructureless mud, sand, pebble admixture
Dmm(r)Dmm with evidence of resedimentationAppears structureless but close examination shows subtle texture and fine structure
Dmm(c)Dmm with evidence of current reworkingAppears structureless but close examination shows subtle texture and fine structure
Dmm(s)Dmm with evidence of shearingPresence of distinctively shaped clasts parallel to flow direction, sheared
DmsMatrix supported stratified diamictTextural differentiation or structure readily apparent
Dms(r), Dms(c)Dms with evidence of resedimentation or current reworkingAs above
DmgMatrix supported, gradedVariable vertical grading in either matrix or clast content
  • After Jones et al. (1999).