 Animals were suffocated and burned in pyroclastic flows within a hundred miles of the event, and died of slow suffocation and starvation much farther away, notably at Ashfall Fossil Beds, located 1,000 miles downwind in northeastern Nebraska, where up to two meters of ash were deposited.At the time, the caldera was above the Yellowstone hotspot.By its uniquely characteristic chemical composition and the distinctive size and shape of its crystals and glass shards, the volcano stood out among dozens of prominent ashfall horizons laid down in the Cretaceous, Paleogene, and Neogene periods of central North America.