RONDON, Formation

UPPER TERTIARY to QUATERNARY

State of Monagas, Venezuela

Author of name: R. A. Liddle, 1928.

Original reference: R. A. Liddle, 1928, p. 339-34?.

Original description: ibid.

The type locality is at Mesa Rondón between the towns of Punceres and Aragua de Maturín in northern Monagas.

The essential features of the original description are as follows: mottled red and white, slightly indurated, argillaceous sandstones and arenaceous clays and underlying soft, brown, locally cross-bedded sandstones and grayish-brown clay-shales. Thickness of these sediments in the area of Mesa Rondón was given at between 250 and 300 feet.

Later workers have been inclined to consider the Rondón formation of Liddle as including parts of the Mesa formation and Sacacual group. The term Rondón formation is not now in general use by stratigraphers in Venezuela.

See also RONDON MESA BEDS

RONDON MESA, Beds

TERTIARY (Miocene ? Pliocene ?)

State of Monagas, Venezuela

Author of name: unknown.

Original reference: C. Schuchert, 1935, p. 683.

Original description: none.

Schuchert (1935, p. 683), discussing the Miocene of Venezuela, states that the "Rondón Mesa beds of northeastern Venezuela, 200 feet thick, are the equivalent of the La Villa" formation of western Venezuela, which he refers to early upper Miocene age.

It seems likely that Schuchert originated this name to designate beds mentioned briefly by Liddle (1928, p. 328), in connection with the Rondón formation: "A few kilometers west of Mesa Rondón, in Río Guayuta on the Rondón-Aragua de Maturín trail, these beds" (i.e. the Rondón formation) "unconformably overlie gray arenaceous, micaceous, lignitic shales containing a middle Miocene flora similar to the one found at Palmarejo in middle Miocene deposits of Damsite age".

The undersigned is not familiar with the detailed geology of Monagas, and is unable to determine which formation, in modern nomenclature, Schuchert's Rondón Mesa represents, but believes it might be part of the Sacacual group as defined by Hedberg (1950, p. 1206-1207), possibly the Las Piedras formation, which is said to have yielded well preserved plant remains in various localities. The Las Piedras formation is now considered upper Miocene and Pliocene.

Frances de Rivero