A LETTER FROM DES RE: PAWOD “ROCK”

Hi Doc!

I read your blog regarding the limestone sample from Pawod Cave. My initial guess is that the limestone belongs to Carcar Formation. This limestone formation fringes most of the coastal areas of Cebu. If my guess is right, it’s age would range from Late Pliocene to Pleistocene, about 1.8 – 3 million years ago. The corals suggest it is a shallow marine area before.

I tried locating Pawod Cave in Google Earth but I had a hard time. May I ask for the exact Barangay or Municipality where the cave is located? Better if you can send me a google earth link of the cave’s location so I can locate the spot easier. That way we can confirm to which rock formation the limestone belongs to and from there I can research for its age. If we want to be a bit precise, we can have the sample prepared and inspected for fossils which will tell us the age of the rock itself. That would be a bit tedious but I can work it out. 😀

Regarding the scorched look, if it is caused by a high temperature impact like from a pyroclastic material, we should be able to find some portions of the rock which will look like a marble- it becomes somewhat a metamorphic rock due to the heat. My other guess is that it’s either deposition of other organics/carbonaceous material or manganese stains. If the stains are caused by the volcanic eruption, it would be fun to find out the effects of the eruption to the area and to reconstruct the history of the formation of this cave.

I hope I can see the sample sometime and provide a more accurate answer.

I hope this helps.:D

Des

Lourdes Christian R. Alejan
Geologist/QAQC In-Charge
Philex Mining Corporation
27 Brixton St., Brgy Kapitolyo,
Pasig City, Philippines