From 1,400 books to one of the world’s largest Earth science collections 📚🌎 When the USGS was established in 1879, the library started with just 1,400 books—supporting early efforts to explore and understand the nation’s landscapes. Today, it has grown into one of the most comprehensive Earth science collections in the world: 📖 1.5 million volumes 🗺️ 750,000 maps 📷 500,000 historical photos 📝 30,000 field records Whether you’re tracing the history of a volcanic eruption, studying water resources, or exploring decades of fieldwork, the USGS library has resources that can help. During National Library Week, we recognize the USGS Library and libraries everywhere for preserving knowledge, supporting discovery, and connecting generations of science. Explore the collections 👉 ow.ly/Y1es50YPsMc 📷1: USGS library reading room in the Interior Building, Washington, D.C. 1935. 📷2: USGS library in the Hooe Building, Washington, D.C. 1917. 📷3: USGS library display of the world-famous George Frederick Kunz library of gems and precious stones. Washington, D.C. 1935. #NationalLibraryWeek

How a prehistoric lake helped carve the Grand Canyon 💧 Scientific discussion about the formation of the Grand Canyon began in 1869, with an expedition led by John Wesley Powell, a pioneering geologist and future director of the USGS. Powell navigated the Colorado River by boat, advanced early theories about the canyon’s origins and demonstrated the national need for a dedicated science agency—work that ultimately contributed to the creation and mission of the USGS. That legacy of exploration continues today, as researchers uncover new insights into the Grand Canyon’s origins. A new collaborative study led by the USGS provides strong evidence that the Grand Canyon was carved out by spillover flooding from ancient Lake Bidahochi, a large lake fed by the ancestral Colorado River. The lake’s eventual spillover likely helped establish the course of the Colorado River. Beginning about 6.6 million years ago, the sand within these lake deposits shows a clear and distinct Colorado River signature. Two million or so years later, evidence indicates the river system had fully integrated, connecting headwaters in the Rockies all the way to the Pacific through the Gulf of California, thus carving what is now the Grand Canyon along the way. Learn more about the study here: ow.ly/hjhG50YLeSR 📷: At Greasewood mesa the contrast between the dark red mudstone beds and the tan sand-dominated layers above marks the arrival of Colorado River sediment into the Bidahochi basin 6.6 million years ago. Photo by Brian Gootee, Arizona Geological Survey. Any person(s) wishing to conduct unmanned aerial vehicle flights on the Navajo Nation must first apply for and receive a permit from the Navajo Department of Transportation.

Regional view. Reliable data. Meet the USGS 250K OnDemand Topo. Big landscapes need big-picture maps. At 1:250,000 scale (1 inch ≈ 4 miles), it’s ideal for regional views—elevation, hydrography, boundaries, & more. Build your own custom 250K Topo👉 topobuilder.nationalmap.gov/

Maps from the 1800s. Unpublished photos of earthquakes and volcanoes. Decades of handwritten field notes. That’s just a glimpse of the USGS Library — one of the world’s most comprehensive Earth science libraries. Explore the collections 👉library.usgs.gov  #America250

Drawing the contours of a nation in the making. ✏️🗺️ In the late 1800s, topographers braved rugged terrain and harsh conditions to map the U.S.—long before aerial photos or GPS. Their work laid the foundation for America’s first detailed maps. History: pubs.usgs.gov/circ/1341 #America250 #TopographicMapping

Mapping history, one contour at a time! 🗺️ Just another day in 1952 for USGS cartographers, mapping the landscape. 145+ years later, topo maps still guide scientists, governments, and weekend explorers. More on the history of topographic mapping here: pubs.usgs.gov/circ/1341

🗺️ Just released: A New Cooperative National Geologic Map for the Nation - This new map gives a unified, detailed look at the geology of the contiguous U.S., compiled from decades of work by state and federal surveys. Learn more: ow.ly/QKxj50WObuw

Water connects us all, cycling through air, land, and underground in liquid, solid, and gas form. Our Water Cycle Diagram depicts the global water cycle, as well as how human water use affects where water is stored and how it moves.