 Here's some more detailed map of the subduction zone volcanism on the west coast of Mexico in the Guadalajara region. So let's orient ourselves. Here is the metropolis of Guadalajara right here. And here's the town of Tequila over here. True fact for the day, the Jose Cuervo Distillery is actually in this town. Now, to have a kind of a volcanic history of this region, let's go back about 11 million years ago, and that's when the San Cristobal basalt was erupting. And this eruption basically spread out over everything within this boundary here, given by the darker shading in this figure, and off the map to the southeast and all the way back around. So this basalt covered everything within there. Basaltic eruptions are usually high temperature and low viscosity, which means they flow pretty readily, think of Hawaii, and they cover everything. So all this area was covered by basalt. Then about 7 million years ago, the character of the mineralogy of the lava is coming out of these volcanoes changed, and they became more solistic. So a solistic lava is like a rhyolite. And the area that those lavas covered is shown by the stippled region, and I'm outlining it too. Rhyolites are much more viscous. They melt at a lower temperature, and so they're kind of like the toothpaste of lavas. They're so viscous, and they often have a lot of gas trapped in them, that they lead to very explosive eruptions quite commonly. Sometimes so explosive that you blow away the entire mountain during the eruption, and in fact there's evidence that that did happen here. So all these sort of circular features like this are collapsed calderas. These happen when you get a giant eruption that blows away the entire mountain and leaves a little depression behind, volcanism can still happen in there. And so La Primavera caldera is one of these calderas, and it's right here. And it's in a line of other rhyolitic vents. Here's another one. And all these other little dots around here are other rhyolitic vents. So this is a very, very active region.