I found something interesting about soils of the Philippines when I visited there for a voluntary activity.
To procure soils for workshops, I and the team of earth architecture visited an empty lot next to San Isidro Labrador Parish Church. It seemed like lots of rocks and gravels were spread all over at the lot at first sight, so I thought that it could be difficult to get soils from there.
However, interestingly, when I touched small rocklike particles, they were amazingly light-weight and easily detached.
When I showed them to Prof Hwang, he assumed it could be lumps of dry soils after moisture was being evaporated. When I pressed them hard with my fingers, some of them were easily separated into a smaller lump of soil.
To test more about them, we put them into a jar filled with water and examine if they were turned into small particles. There were no dramatic changes when they were soaked into water unless we pressed them hard with fingers to divide them into small pieces.
Since it required a long time to turn them into small pieces, instead of using them, we dug the ground, and sieve soils. To be honest, the local soils were too dry, digging was not an easy process.
Anyway, it was an interesting discovery about soils of the Philippines. The time we visited was the winter season which was relatively dry, so it was possible to imagine that in the summer or monsoon season, those rocklike soils will be turned into clayish soils.
If I have a chance to visit the Philippines again in the future, I would love to study more about soils.