Estratos de San Pedro is the name given to the sedimentary strata of Paleogene age that crop out along San Pedro River, southern Chile. The strata were initially described by

Juan Brüggen Johannes Brüggen Messtorff better known by his hispanized name Juan Brüggen (Lübeck, Germany, April 25, 1887 – March 7, 1953, Santiago de Chile) was a German-Chilean geologist. One of his most famous works is the extensive treaty of ''Funda ...

and later briefly investigated by

Henning Illies Jürgen Henning Illies (14 March 1924 – 2 August 1982) was a German geologist, an expert in taphrogenesis (rift formation). Apart from his work on rifts, including the Rhine Rift Valley, he is known for his contributions to Chilean geology. ...

who estimated their thickness at . The strata are made up of

conglomerate Conglomerate or conglomeration may refer to: * Conglomerate (company) * Conglomerate (geology) * Conglomerate (mathematics) In popular culture: * The Conglomerate (American group), a production crew and musical group founded by Busta Rhymes ** Co ...

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) ...

and

mudstone Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from '' shale'' by its lack of fissility (parallel layering).Blatt, H., and R.J. Tracy, 1996, ''Petrology. ...

(

Chilean Spanish Chilean Spanish ( es, español chileno) is any of several varieties of the Spanish language spoken in most of Chile. Chilean Spanish dialects have distinctive pronunciation, grammar, vocabulary, and slang usages that differ from those of Stand ...

: ''fangolita''). The clasts of the conglomerates are made up of

metamorphic rock Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causin ...

and the disposition of the conglomerates varies from clast-supported to matrix-supported. The sandstone and mudstone contains layers of lignite coal that exceed in thickness.

References

Geologic formations of Chile Miocene Series of South America Oligocene Series of South America Eocene Series of South America Paleogene Chile Neogene Chile Sandstone formations Geology of Los Ríos Region {{Chile-stub