Commentary
The Geology of the Ob-Ob Hill Formation and some Beach Sands in Batan Stretch are so Black
By: Raymond Sucgang
I received an FB message from Dr. Americus Perez last night about his updates on the geology of the Ob-Ob hill. Dr Perez is currently in Japan analyzing samples collected from the Philippines and one of those are samples from Batan, Aklan.
According to Doc Eric, the Ob-ob hill consists of Basaltic Andesite , meaning 54 % silicon. Now we know bakit napaka itim ng sand.
Basaltic andesite is a type of volcanic rock that falls between basalt and andesite in terms of composition. It typically contains minerals like plagioclase feldspar, pyroxene, and olivine. Basaltic andesite is formed from magma that is intermediate in silica content, which means it is less viscous than andesite but more viscous than basalt.
This composition often results in eruptions characterized by both effusive (fluid) and explosive (violent) activity. Basaltic andesite lava flows can create features such as lava channels, lava tubes, and lava domes, depending on their viscosity and eruption conditions.
In short it was a volcano , an ancient one that spew this Hill and the sands and thus the materials came from below the Earth’s crust and the composition was dependent on the magma from beneath the Earth’s crust and the processes that lead to its eruption. Later this week Doc Eric will give us a better narrative about this formation. And sana also an update about the study on the Mambuquiao ” Galleon.”
(Raymond Sucgang is a senior research at the DOST-PNRI)
