The 1st bottom Rio Grande and Harlingen soils are youngest; the Laredo occurring in natural levee or high first bottom positions are 2nd; the terrace Victoria and Hidalgo soils with moderately well developed but incomplete profiles are 3rd; and the Brennan, Willacy, Duval, and Nueces soils have attained the mature profile for this section. The youngest soils have absolutely no evidence of leaching or greater accumulation of soil lime in any particular horizon within the section. The Laredo soils show a fairly uniform reaction with HC1 throughout the section. The 3rd stage soils effervesce from the surface downward, the effervescence increasing with depth. The 4th stage soils above 30-36 in. have been entirely leached of carbonates. Below this is a layer, similar to the lower material of the Victoria and Hidalgo soils, which is highly calcareous and contains much sofy white lime in large and small accretions and concretions. Caliche, somewhat indurated in the surface, is found at 6-8 ft. below the Brennan soils but is absent under the Willacy soils. The ultimate stage of lime development is found in the Duval and Nueces soils. No effervescence occurs above the caliche, which is found at depths of 3-8 ft. and is quite hard in the surface at the shallower depths. The stages are definitely linked with the age of material.