Rocks and water samples were collected from Pawod Cave on 30 May 2013 at a depth of 15 feet and 40 feet from the cave entrance. Water collected along with the rock samples had an average salinity of 5 parts per thousand and a pH of 6.0, consistent with brackish water. The rock samples are coral fragments and coral rubble embedded in soft limestone.
Outer surfaces of the samples have black or brown patches that upon closer inspection appear to form a distinct layer over the coral skeleton, suggesting that this coloration may have been caused by the deposition of minerals and organic matter.
Further analysis of the composition of the coral surfaces, as well as of water and sediments in the cave are needed.
General morphology of the samples and surface scrapings are described below:
- Morphology: Tubular fragments of branching coral with visible coral polyp cavities
- Color: Cream white with black patches on surface
- Texture: Crusty, black coloration can easily be removed
- Organics: Microscopic green algae present, as well as spiral-shaped cyanobacteria. Cells disintegrated due to crushing
- Morphology: Branch-like
- Color: Black on upper surface; white and brown underside
- Texture: Slightly crusty, flat, laminated
- Organics: None, only mineral crystals observed
- Morphology: Domed, convex fragment of massive coral
- Color: Cream white with brown sections
- Texture: Crusty, some parts are powdery, corallites with wrinkled margins are present
- Organics: None
- Morphology: Irregular with embedded tubular coral fragments
- Color: Cream to brownish limestone on the main body and embedded fragments are black on the surface
- Texture: Crusty projections; smooth main body
- Organics: None
Report by:
Filipino Cave Divers 