The Show-Me State has plenty of geology to show, including the biggest entry room of any cave in North America, the largest lead deposit in the United States, and the only exposures in the Midwest of a large province of 1.48-billion-year-old granite and rhyolite. Geologic history is still being made here, too. In 1811 and 1812, an unprecedented series of magnitude 7 and 8 earthquakes rocked southeast Missouri, liquefying the floodplain sediments and temporarily blocking the flow of the Mississippi River.