page_title: Alajuela Formation
section_title: Stratigraphy
hierarchical_section_title: Alajuela Formation / Description / Stratigraphy
caption_attribution_description: English: Stratigraphic of the Alajuela Formation, Panama
context_page_description: The Alajuela Formation, originally Alhajuela Formation, is a Late Miocene geologic formation in the Panama Canal Zone of central Panama.
  The formation overlies the Caimito Formation and comprises sandstones, limestones and conglomerates deposited in a tidal-dominated estuarine to shallow marine environment.
  The formation crops out in a small area along the southern and western shores of Lake Alajuela, of which it derives its name, and preserves a rich fossil faunal assemblage of mammals, fish, invertebrates and flora. The fauna is of paleontological significance as an insight into the ecosystem of Central America preceding the Great American Biotic Interchange.
context_section_description: While Woodring originally described the formation in two members, MacFadden et al. (2017) define three distinct lithological intervals in the composite section, measured in proximity to the fossil localities on the southern extent of Lago Alajuela, of the formation. The succession starts with a more than 25 metres (82 ft) thick basal package of interbedded, clast-supported conglomerates and litharenite sandstones, grading into an approximately 85 metres (279 ft) thick package of calcareous sandstones and calcarenites, representing a transition from tide-dominated, potentially estuarine, coastal environment to a wave-dominated, shallow water carbonate environment.
caption: Composite stratigraphic section of 82 m (269 ft) of the Alajuela Formation. Fossil localities are indicated.
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