The Origin of Several Pyroclastic Plateaux in the Padang Highlands (Central Sumatra) (Preliminary Paper)
Abstract. Several pyroclastic plateaux are known in the Padang Highlands. Westerveld (1952) suggested that those rhyolitic volcanics are sheetlike deposits of paroxysmal fissure eruption similar to the incandescent clouds of the Katmai type. Field observation, however, suggested that at least the pyroclastic plateau of Bukit Tinggi might as well be the result of an air borne tuff deposition which originated from a gigantic outburst of the Manindjau volcano prior to its caldera formation. The tuff plateau of Bukit Tinggi, as revealed by the exposures in Ngarai SiAnok, is neither layered nor welded and could not be deposited in water either. The landscape between Matur and Bukit Tinggi gives the impression as if ducoed by tuff from the air.