Formed during an onset of volcanic activity about 100, 000 years ago, the Plinth Assemblage consists of light grey porphyritic rhyodacite with phenocrysts of plagioclase, quartz, minor biotite and rare hornblende.
42.
Later eruptions created cinder cones such as Wizard Island ( c . 6, 000 years old and high ) and Merriam Cone and also rhyodacite domes ( most of these features are under water ).
43.
Volcanism in the area occurred in two phases, an earlier andesitic phase called the Rondal formation and during the Quechua orogeny a second phase associated with rhyodacite forming lava domes, lava flows and pyroclastic flows ( up to thick ).
44.
I am aware there are terms in the article that make it a little technical to read like rock types ( e . g . dacite, rhyodacite, andesite, rhyolite, breccia ) and other volcanological terminology, but as far as I am aware of they are appropiate for FA volcano articles.
45.
Later eruptive activity formed the rhyodacite ( ) 114, 000 years ago northwest of Laguna del Maule, a neighbouring rhyodacite west of Laguna del Maule dam, basaltic ( ) 63, 000 62, 000 years ago near the outlet of Laguna del Maule, a rhyolite east of the outlet 38, 000 ?29, 000 years ago, and andesites also west of the dam 27, 000 26, 000 years ago named.
46.
Later eruptive activity formed the rhyodacite ( ) 114, 000 years ago northwest of Laguna del Maule, a neighbouring rhyodacite west of Laguna del Maule dam, basaltic ( ) 63, 000 62, 000 years ago near the outlet of Laguna del Maule, a rhyolite east of the outlet 38, 000 ?29, 000 years ago, and andesites also west of the dam 27, 000 26, 000 years ago named.
