For some time now, I've noticed that mountains in southeast Asia seem to be unusually "jagged" with steep surfaces. My basic knowledge of how mountains are formed (via geologic processes) tells me that it's more common to find mountains like these in glacial areas (e.g. northern Canada, Norway, etc.), whereas those formed by tectonic plate collisions appear more "traditional" (e.g. main range of Himalayas, Andes, etc.), and geologically old mountains have a weathered appearance (e.g. Appalachians).
What caused/causes these SE Asian mountains to have their distinct appearance?
Examples (from Flickr):