English to Russian Science Geology

Тема литология. Как перевести слово trace в этих сочетаниях?
LEGEND
CLAY
Clayey SILT
Silty CLAY
Very Fine SAND and SILT, trace mica
Very fine to Fine SAND trace silt & mica
Fine SAND, little silt trace mica
Fine to Medium SAND, trace silt & mica
Medium SAND, some fine sand, little fine sand, trace silt & mica
Medium to Coarse SAND, some fine sand, trace silt & mica
Coarse SAND and Gravels, some md. & fine sand, trace silt & mica
Clayey SAND, with Gravels

Lithology
CLAY
Clayey SLT
Silty CLAY
VFSD & SLT
VF to FSD & trace SLT
FSD, little SLT
F to MSD
MSD, some FSD
M to CSD, some FSD
CSD & some MSD
G & CSD, some M & FSD