LLANOS, Beds

See LLANOS, Formation

LLANOS, Formation

QUATERNARY

States of Sucre, Monagas and Anzoátegui, Venezuela

Author of name: A. H. Garner.

Original reference: A. H. Garner, 1926, p. 2 and 7.

Original description: A. H. Garner, 1926, p. 7.

Among the different authors who have studied the Quaternary deposits which constitute the surface of the Venezuelan llanos, we will only mention Humboldt (1925), Sachs (1879) who gives some geologic section, Dalton (1912) who gives the name "Llanos deposits", Jahn (1921), and recently González de Juana (1946), and Davey (1946).

Garner (1926, p. 7) was first to use the name Llanos formation by saying that lt is made up of coarse, polygenic, colored, poorly sorted, massive sandstone and mottled, white clays, with much flat lying iron oxide. When mentioning the type-locality, he says that it is exposed in most stream beds and on mesas over southern Monagas and Anzoátegui. He assigns it to the Quaternary and correlates it with the Tablazos formation of eastern Zulia. In his correlation chart, Garner places the "Alluvials" in the division above the "Quaternary" which is used as a synonym of Pleistocene; therefore his "Alluvials" are synonymous with Alluvial, Recent or Holocene. According to the description, it seems that he includes in it the Mesa formation or part of it.

In his correlation of formations of the Barinas region, A. N. Mackenzie (1937) uses the name Llanos formation. He considers it as Recent, 300 to 600 meters thick and made-up of clays, sands, and gravels, locally consolidated by induration. In the text (p. 283), he states that the Llanos formation (Recent) includes all of the Pliocene rocks in the vicinity that have been called Llanos by R. A. Liddle. Later he calls them "Llanos beds" and in his stratigraphic section he writes: "Pliocene (Llanos series) Quiriquire formation" (with the four zones).

H. D. Hedberg (1938) considers that Garner's "Llanos formation" is of uncertain extension and that it should not be used without a precise definition. It could be added to Hedberg's statement that Garner's name does not refer to a determiùate extension but to a rather vast extension and that furthermore, it has been used in different ways, as shown in the above paragraphs; being thus inappropriate to designate a formation.

José Royo y Gómez