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A historical image of visitors and bears in Yellowstone National Park.

Topographer George Stanley Druhot working with a tripod, planetable, and alidade at Kahekili Leap, on the island of Oahu. His two companions are Malcolm Springer and Tai Hai Lau

Two topographers working with an alidade and plane table. The man on the right is believed to be Roland Whitman Burchard, who was the topographer for the USGS Grand Canyon Expedition of 1923. Author Lewis Freeman described Burchard as a man of "powerful physique, great endurance, and a cool, steady hand."

Topographer George Stanley Druhot running a level line on oil-shale cliffs north of the Colorado River. The level line was one mile long and climbed 2,000 feet over talus slopes.

This scene west of Halemaumau looks toward the rim of the caldera, southwest of Uēkahuna Bluff. New ballistic blocks and ash from the 1924 eruption coat the floor of the caldera.

Prior to the eruption of 1924, this area was swept clean and used as a landing field for airplanes. This view looking toward the north rim of Halemaumau shows the air field littered with ballistic blocks from explosions in the 1924 eruption.

This was probably the strongest explosion of the eruption. Rocks and debris fell among spectators southeast of Halemaumau, causing one fatality. A torrential downpour and an electrical storm followed.

Acting HVO director Ruy Finch snapped this photograph of spectators running away as large blocks were tossed about 600 meters (2000 feet) onto an airplane landing field. Lorrin A.

Boles poses on the grounds of the Volcano House hotel with the Halemaumau eruption plume in the background. He fell cutting his hands and a knee while fleeing an explosion the day before. After his close call the superintendent barred all public access within two miles of Halemaumau.

Eight persons, including newspaper and movie men observing the scene at Halema‘uma‘u, were caught in a rain of hot rocks from this explosion. The rocks emitted hissing sounds as hot gas, mainly steam, escaped from them. Park superintendent Thomas Boles was knocked down twice by this bombardment.

On May 11, Ruy Finch and W.O. Clark visited Halemaumau and found a rock fragment weighing about 180 kg (400 pounds) that had been thrown 60 meters (200 feet) from the rim of the crater.

Later scientists at the Observatory listed May 10 as the first day of the eruptive series. Between this date and May 27, they carefully recorded all explosions, ballistic falls, electric storms, and muddy rains as well as earthquakes felt and recorded on seismographs.

Scientists looking into the bright glow of Mauna Loa's 1942 eruptive vent. Eruption occurred during WWII and was not publicized to prevent Japanese war planes from navigating to the island at night.

R.R. Monbeck on the rim of Haleakala volcano on the island of Maui

Early visitors at Handkerchief Pool, Black Sand Basin, around 1923.