While the aforementioned volcanic types have largely localized effects a supervolcano, consisting of a huge caldera up to several hundred kilometres across, can cause devastation on a continental scale. Such eruptions, although their explosivity varies, could radically alter the landscape and severely affect global climate for years due to the sheer volume of the ejected material (e.g. the last eruption of the Yellowstone Caldera, USA, produced ~1000 km³ of rhyolitic lavas and ash some 640.000 years ago). Even more extensive were the flood basalt extrusions during the Cretaceous that formed the Etendeka / Parana Plateaus of Namibia and Brazil, Shield volcano Skjaldbreidur, Iceland Cinder cone "Sunset Crater", Arizona Ash plume erupting from stratovolcano Mt. Cleveland, Alaska (as seen from the International Space Station) respectively, with an estimated extruded volume of ca. 200.000 km³ - which is not particularly large as such events go!