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Río Cachirí Group
The Río Cachirí Group (, PZc) is a group (geology), geological group of the Cesar-Ranchería Basin, Colombia and the Serranía del Perijá of the northernmost Colombian and Venezuelan Andes. The group of shales, sandstones and limestones is of Devonian age and has a maximum thickness in the Venezuelan section of . The group contains abundant fauna; crinoids, bryozoa, brachiopods and molluscs have been found in the group. Etymology and definition The formation was defined by Liddle in 1928 in Mara, Zulia, Río Cachirí, part of Mara, Zulia, in the Venezuelan part of the Serranía del Perijá, and the same author subdivided the group into three formations in 1943. In 1972, Bowen added a fourth formation to the group.Ayala, 2009, p.20 Description Lithologies The group contains black, grey and red shales, grey micaceous sandstones, quartzite, quartzitic sandstones and red and bluish grey limestones. Stratigraphy and correlation The Río Cachirí Group, dated to span the De ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Devonian
The Devonian ( ) is a period (geology), geologic period and system (stratigraphy), system of the Paleozoic era (geology), era during the Phanerozoic eon (geology), eon, spanning 60.3 million years from the end of the preceding Silurian period at million years ago (Megaannum, Ma), to the beginning of the succeeding Carboniferous period at Ma. It is the fourth period of both the Paleozoic and the Phanerozoic. It is named after Devon, South West England, where rocks from this period were first studied. The first significant evolutionary radiation of history of life#Colonization of land, life on land occurred during the Devonian, as free-spore, sporing land plants (pteridophytes) began to spread across dry land, forming extensive coal forests which covered the continents. By the middle of the Devonian, several groups of vascular plants had evolved leaf, leaves and true roots, and by the end of the period the first seed-bearing plants (Pteridospermatophyta, pteridospermatophyt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
