Three caldera-forming events occurred during the system's lifespan. The first took place 1.5million years ago and produced the dacitic Laguna Sin Puerto ignimbrite, which is exposed northwest of Laguna del Maule lake. The second occurred between 990,000 and 950,000years ago and produced the Bobadilla caldera and a rhyodacitic ignimbrite, also known as the Cajones de Bobadilla ignimbrite. This ignimbrite reaches a thickness of and borders Laguna del Maule lake in the north. The Bobadilla caldera is centred beneath the northern shore of Laguna del Maule, and has dimensions of . The third took place 336,000years ago and produced the welded Cordon Constanza ignimbrite.