page_title: La Toca Formation
section_title: Description
hierarchical_section_title: La Toca Formation / Description
caption_attribution_description: English: Mzb are Mesozoic amphibolites and associated metasedimentary rocks, Ki are Cretaceous plutons, Kv are Cretaceous volcanic rocks, uK are Upper Cretaceous marine strata, Ku are Cretaceous sedimentary and volcanic rocks, K are Cretaceous marine strata, IT are Eocene and/or Paleocene marine strata, uT are Post-Eocene marine strata, T are Tertiary marine strata, V are volcanic rocks, and Q are Quaternary alluvium
context_page_description: The La Toca Formation is a geologic formation in the northern and eastern part of the Dominican Republic. The formation, predominantly an alternating sequence of marls and turbiditic sandstones, breccias and conglomerates, is renowned for the preservation of insects and other arthropods in amber, known as Dominican amber. The formation is dated to the Burdigalian to Langhian stages of the Miocene period.
context_section_description: La Toca Formation was first defined by Redmond in 1982. The formation mainly consists of marls and turbiditic sandstones and conglomerates deposited in the northeastern part of Hispaniola. The formation overlies the Los Hidalgos Formation and is overlain by the La Jaiba Conglomerate and in places by the Villa Trina Formation. It is laterally and time-equivalent with the Altamira and Luperón Formations and the Agua Clara Unit.
  Esperanza
  In the vicinity of Esperanza, La Toca Formation is cropping out in the northeast of the geologic map, while it is also present in the neighboring municipalities of Imbert and San Francisco Arriba. The formation in this area comprises rhythmic alternations of ochre fine-to-medium-grained, locally grading to course-grained sandstones and greyish clayey and ochre marls. This succession is locally cut by meters thick microconglomerates and conglomerates with rounded and subrounded clasts. Analysis of the clasts in San Francisco Arriba shows the clasts consist of up to ten percent of volcanic rock fragments, mainly limestone fragments (23-42%), quartz (8-33%), chert of up to five percent and minor metamorphic rock fragments. The matrix which comprises about a quarter of the volume is micritic.
  The formation is in this area poor in microfossils, although foraminifera of Catapsydrax af. dissimilis, Globigerinoides trilobus, Globigerina sp., Globorotalia sp., Cibicides sp., Brizalina sp., Reophax sp., ?Cassidulina sp. and Pirgo sp. have been found in the succession.
  Turbidite deposition moved to the northeast during the Miocene.
caption: Geologic map of Hispaniola. La Toca Formation forms part of the brown-colored areas in the north and northeast of the island, indicated by uT. The black triangles indicate the Late Eocene Hatillo thrust fault.
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