Cobre Ridge caldera

The Cobre Ridge caldera is a large Jurassic volcano in the U.S. state of Arizona. It formed about 170 million years ago when a VEI-8 eruption ejected more than {{convert|1000|km3|mi3|abbr=on}} of crystal-rich rhyodacite ignimbrite.{{Cite journal |last=Riggs |first=Nancy R. |last2=Busby-Spera |first2=Cathy J. |date=1991 |title=Facies analysis of an ancient, dismembered, large caldera complex and implications for intra-arc subsidence: Middle Jurassic strata of Cobre Ridge, southern Arizona, USA |url=https://linkinghub.elsevier.com/retrieve/pii/003707389190034B |journal=Sedimentary Geology |language=en |volume=74 |issue=1-4 |pages=39–68 |doi=10.1016/0037-0738(91)90034-B}}