In the Pacific Northwest, oozing volcanic basalts erupted over the landscape during the middle Miocene, layering a sequence of 43 distinct strata, comprising roughly 350 individual flows, up to 2 kilometers thick over roughly 210,000 square kilometers. The timeline over which all that rock, known as the Columbia River Basalt Group (CRBG), piled up — and the pace at which it did so — hasn’t been as clear as scientists would like, in part because prior dates for the lava flows have come with large uncertainties. But in a new study in Science Advances, researchers have reduced those uncertainties and shown that the vast majority of the massive CRBG was deposited in less than a million years.