Re: Upper boundary of argillic horizon and evidence of illuviation?

Andrew, my understanding is that the top of the argillic is where you see evidence of translocation of clay, as long as the clay increase requirements are met. The clay increase must be met within 30 cm of that depth. However, if a lithologic discontinuity or the bottom of a plow layer where the translocated clay is observed, the clay increase requirements are waived.