The La Meseta Formation is a sedimentary sequence deposited during much of the Paleogene on Seymour Island off the coast of the Antarctic Peninsula.

It is an approximately 557 metres (1,827 ft) thick sequence of poorly consolidated sandstones and siltstones.

[3][2] La Meseta Formation is one of the sequences that make up the fill of the Late Jurassic to Paleogene James Ross Basin.

[3] The terrestrial environment surrounding the deposition area is thought to have been a temperate polar forest, including podocarp and araucarian conifers, as well as Nothofagus.

[9][10] Most of the fossilized woods and flowers discovered on Seymour Islands consist of extinct species of conifer trees and lilies during warm climate.