(vi) Calcic and petrocalcic horizons (Bk and Bkm or Ck and Ckm) show an accumulation of carbonate and they commonly lie below argillic and cambic horizons in Aridisols. Generally, carbonates are leached out before clay are translocated to form an argillic horizon. Calcic horizons develop over time into petrocalcic horizons, which are indurated calcic horizons cemented by calcium carbonate and in some places with magnesium carbonate. Petrocalcic horizons cannot be penetrated with a spade or auger when dry and the cemented layer is impenetrable to roots. .