A key bed is a distinctive layer of rock that is used to correlate different rock formations across a large geographic area. An event like a large hurricane can create a key bed by depositing a significant amount of sediment that is different in composition or texture than the surrounding rock. For example, Hurricane Katrina, which hit the Gulf Coast of the United States in 2005, resulted in a key bed that was created by the massive storm surge and flooding that followed. As the floodwaters receded, they left behind a layer of fine-grained sediment that was distinct from the surrounding rock. This layer, known as the Katrina Key Bed, can be used by geologists to correlate rock formations across a large area and to date other events in the region that occurred before or after the hurricane. Thus, natural disasters like hurricanes can create important geological features that can help scientists better understand the history of the earth.