Images

Clinker coal is the result of a seam of coal catching fire and burning so hot that it baked surrounding rock layers into brick-like formations.

Clinker coal is the result of a seam of coal catching fire and burning so hot that it baked surrounding rock layers into brick-like formations.

A sample of lignite, the lowest rank of coal. It is primarily mined for burning in steam-generation power plants.

A sample of lignite, the lowest rank of coal. It is primarily mined for burning in steam-generation power plants.

A sample of lignite, the lowest rank of coal. It is primarily mined for burning in steam-generation power plants.

Peat is the precursor to coal. It's made up of decayed plant materials or other organic matter that, over time, can undergo heat and pressure to become lignite.

This sample is of peacock coal. Peacock coal is not a specific class of coal, but rather the name for an effect in which oxidizing materials in the coal create a dazzling array of colors on the surface of the coal. Usually it is short-lived, as the material fully oxidizes away shortly after exposed to air.

A former uranium mill tailings site near Rifle, Colorado, is next to the Colorado River.

USGS scientist records information at a sampling site on a stream in Pennsylvania. The stream was sampled immediately downstream of the point of discharge of treated wastewater. 

Most fossils occur in sedimentary rocks including shale, limestone and sandstone. The sandstone block shown here contains a large fossil palm leaf, found at the Coryell Coal mines in Colorado.

Faulted and folded Triassic, Jurassic, and Cretaceous rocks along Surprise Creek in southern part of Western North Slope. The Triassic and Jurassic rocks include petroleum source rocks from which oil was generated. Geologists in orange vests for scale.

Geologists measuring petroleum source rocks in Triassic rocks along Surprise Creek in southern part of Western North Slope.

Geologist describes petroleum source rocks in Triassic and Jurassic rocks along Surprise Creek in southern part of Western North Slope.

A carbon dioxide (CO₂) injection well drilled by the Southeast Regional Carbon Sequestration Partnership (sponsored by the U.S. Department of Energy) at the Cranfield CO₂ test site in Mississippi. The well was drilled to test the effectiveness of injecting and storing CO₂ in a deep saline reservoir.

A drill rig at the Mount Elbert test site in Alaska's North Slope, just west of Prudhoe Bay. USGS joined BP Exploration (Alaska) and the U.S. Department of Energy to drill a test well to study natural gas production from gas hydrate deposits. Read more about the Mt.

This image shows gas hydrates (the white material) in marine sediments from a test well drilled in the Indian Ocean in 2006 during the Indian National Gas Hydrate Program (NGHP) Expedition 01.

This image shows gas hydrates (the white material) in marine sediments from a test well drilled in the Indian Ocean in 2006 during the Indian National Gas Hydrate Program (NGHP) Expedition 01.

This image shows gas hydrates (the white material) in marine sediments from a test well drilled in the Indian Ocean in 2006 during the Indian National Gas Hydrate Program (NGHP) Expedition 01.

This image shows gas hydrates (the white material) in marine sediments from a test well drilled in the Indian Ocean in 2006 during the Indian National Gas Hydrate Program (NGHP) Expedition 01.

USGS scientist Bernard Hubbard conducting spectral measurements of soils and cover crops to ground truth satellite imagery being used to map soil erosion and runoff potential into the Chesapeake Bay watershed.