Tester Dummy Fm

Synonym: Búcaro Fm, Bucaru Fm, Bucarú Fm, Búcaru Fm

Lithology and Thickness: Exposed thickness of Eocene rocks north of Guanico Point is about 2,000 feet. Lower beds are coarse dark-gray sandstones, conglomerates, and sandy shales. These beds are followed by about 1,500 feet of blue-green or black shales with thin gritty sandstones; in their lower part are several fossil zones, the lower about 50 feet above base of section.

Lithology-pattern: Clayey sandstone

Relationships and Distribution:

Lower contact: No data

Upper contact: David Fm

Regional extent:

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Fossils:

The mollusks include Aturia peruviana [nautiloid], Noetiopsis woodringi, and Venericardia tonosiensis (Olsson,1942b (pages 235-236)).

Age:

Age span:

Beginning stage: Ypresian

Fraction up in beginning stage: 0

Beginning date (Ma):

Ending stage: Bartonian

Fraction up in ending stage: 0

Ending date (Ma):

Depositional setting:

Depositional-pattern:

Additional Information

• Senn (1940, pages 1578, 1589). Used the misspelled name of “Bucarú Formation”, without accent.
• Olsson (1942b, pages 235-236). Referred to as Bucarú Formation. Exposed thickness of Eocene rocks north of Guanico Point is about 2,000 feet. Lower beds are coarse dark-gray sandstones, conglomerates, and sandy shales. These beds are followed by about 1,500 feet of blue-green or black shales with thin gritty sandstones; in their lower part are several fossil zones, the lower about 50 feet above base of section. Underlies David Formation. The mollusks include Aturia peruviana [nautiloid], Noetiopsis woodringi, and Venericardia tonosiensis.
• Terry (1956, page 29). Used the spelling Búcaru
• Wilson et al. (1957).
• Woodring (1960). On north side of Point near Búcaro, is in fault contact with volcanics; to south grades downward into volcanics. Lexicon uses Búcaro as preferred spelling. Near village of Búcaro, Los Santos Province. Confirmed that the proper spelling is Búcaro Formation. The formation extends northward up the lower part of the valley of Río Tonoso. Near Búcaro the basal part grades downward into basaltic agglomerate.
• Keroher et al. (1966).