As the climate crisis continues to affect the American West, sunken boats and human remains aren't the only surprises to be revealed by record-low water levels at Lake Mead. Sedimentary rocks that hadn't been seen since the 1930s are now exposed along the constantly changing shoreline, and a UNLV study of the deposits has discovered that many of these rocks also contain ash from volcanoes as far away as Idaho, Wyoming, and California that rained down on Southern Nevada as many as 12 million years ago.