This is the U.S. Geological Survey’s cavernous “rock warehouse,” beloved by scientists but unknown to the rest of us. It holds thousands of boxes of ancient specimens, some 100 million years old, collected from tunnel excavations, abandoned mines, deep sea drill holes, reclaimed quarries and ocean floors. The collection is the culmination of decades of far-flung research, from Antarctica to Ben Lomond.

Once scattered and disorganized, the boxes are now cataloged and organized. The effort, led by retired geophysicist Jon Childs, is part of a new federal project designed to bring structure to chaotic rock collections — and to make sure yesterday’s rocks are useful to tomorrow’s scientists.

“The rock warehouse is an anachronism in a digital age, but it plays an essential role in Earth science. It’s like a museum, or library of seeds,” said Ray E. Wells, a geologist whose Oregon drill borings are stored here.

With each foray out into the field, geologists collect specimens — often at remote sites, at great expense — and carry them back to their labs to study. Then these 21st-century scientists confront the USGS Organic Act of 1879, which directs that “all collections of rocks, minerals, soils, fossils when no longer needed for investigations, shall be deposited in the National Museum,” now known as the Smithsonian — which has little room left for rocks.

While medical researchers can discard dead mice, chemists can toss unneeded solutions and physicists use computers to store old data, geologists are stuck with rocks. Lots of rocks. So year by year, rock by rock, this dusty repository has accumulated almost everything collected by UGSG’s Menlo Park staff since its creation in 1954.

Specimens from Oregon’s Crater Lake reveal the West’s eruptive past. Sedimentary rock deposits from Wyoming and Montana hold rich beds of phosphorus, vital to agriculture. Arctic soil samples show that as permafrost thaws stored carbon is being released, triggering further climate change. Samples from deep within the San Andreas Fault add to our understanding of earthquake risk. These samples can be critical to future researchers, who “might come along and say: ‘That’s exactly the sample I need,’” Childs said.

Moreover, these samples are valuable because many come from places that are too expensive or sensitive to explore again: under the Hollywood Freeway; inside Portland’s TriMet Tunnel; beneath the Bering Sea. “The rock warehouse has enabled precious samples from a wide range of projects to be preserved under carefully controlled conditions for future scientific research,” said Steve Hickman, director of the USGS Earthquake Science Center.