EXPLANATION OF PLATE 4.
Fig. i.-View in pit of Pierce Phosphate Company, showing the irregular top surface of the bed rock (Arcadia marl) after the removal of the phosphate stratum. Phosphate plant in the background.
Fig. 2.-View in the pit of the Coronet Phosphate Company, Lakeland, Fla. Unconformity between the coarse phosphate above and the finer pebble phosphate below. This unconformity, although imperfectly shown in the photograph, is well marked at this locality. The material above is a coarse conglomerate, that beneath is fine pebble imbedded in clay.
Fig. 3.-View in pit of Standard Phosphate Company, showing irregular line of contact, apparent unconformity, between the loose surface sand and the more indurated sand beneath.