Black and white photograph of the Solfatara di Pozzuoli volcanic mud pots.

Black and white photograph of the Solfatara di Pozzuoli volcano fumerole "Boca Grande." A group of people is visible to the right of the Boca Grande. One person is standing in front of the Boca Grande, and a building is visible on the right side of…

Black and white lantern slide of several people gathered around a shallow, smoking pit at the Solfatara volcano in Pozzuoli, Italy.

Volcanic cone near El Morro, New Mexico

Volcanic blow hole near El Morro, New Mexico.

Robert Annis looking at the effects of ice in volcanic blow hole, New Mexico.

Capulin Volcano National Monument outside Raton, New Mexico.

Camp at volcano in El Morro, New Mexico.

Black and white lantern (dark) slide of Mexican landscape with the volcanoes Popocatepetl and Itzaccihuatl in the distance.

Black and white lantern slide of Mexican landscape with the volcanoes Popocatepetl and Itzaccihuatl in the distance, looking southwest.

Water hole marker at Craters of the Moon National Monument, Idaho.

Water hole at Craters of the Moon National Monument, Idaho.