The 30th anniversary of the meltdown at the Chernobyl nuclear plant that caused large amounts of radioactive particles to be released into the air will be commemorated on April 26, 2016. Photojournalist Sean Gallup returned to the area to document the lasting effects of the world's worst nuclear power plant accident. Pictured, children's beds are seen in an abandoned kindergarten in Kopachi village located inside the Chernobyl exclusion zone, September 29, 2015, near Chernobyl, Ukraine. (Photo by Sean Gallup/Getty Images)

A child watching the sea while residents try to clear the bed of a river that has been blocked by debris left by Hurricane Matthew, in the commune of Roche-a-Bateaux, in the south west of Haiti, on October 21, 2016. At least 546 people were killed and more than 175,000 people lost their homes when Hurricane Matthew roared ashore on October 4, packing winds of 145 miles (230 kilometers) per hour. (Photo by Hector Retamal/AFP Photo)

Jacob's Well is a perennial karstic spring in the Texas Hill Country flowing from the bed of Cypress Creek, located northwest of Wimberley, Texas. The twelve foot (four meter) diameter mouth of the spring serves as a popular swimming spot for the local land owners whose properties adjoin Cypress Creek. From the opening in the creek bed, Jacob's Well cave descends vertically for about thirty feet (ten meters), then continues downward at an angle through a series of silted chambers separated by narrow restrictions, finally reaching a depth of one hundred and twenty feet (forty meters). Until the modern era, the Trinity Aquifer-fed natural artesian spring gushed water from the mouth of the cave, with a measured flow in 1924 of one hundred and seventy gallons per second (six hundred and forty liters per second) discharging six feet (two meters) into the air. The spring is the greatest source of water recharging the Edwards Aquifer.

In this July 11, 2016 photo, a young, masked drug trafficker poses for photos holding his guns at a slum in Rio de Janeiro, Brazil. Teenagers openly tote guns while they work as guards, lookouts and distributors for drug lords operating just a few miles from where hundreds of thousands and tourists and athletes will be for the Aug. 5-21 Olympic Games. (Photo by Felipe Dana/AP Photo)

Saudi female firearm trainer, Mona Al Khurais, teaches a Saudi boy on safe usage of weapons at the Top-Gun shooting range in Riyadh, Saudi Arabia, October 28, 2021. (Photo by Ahmed Yosri/Reuters)

A man holds a gun under his chin as he speaks with members of the NYPD outside the United Nations Headquarters in New York City, U.S., December 2, 2021. (Photo by Carlo Allegri/Reuters)

A Ukrainian serviceman fires a 2S7 Pion self-propelled gun during military exercises near the village of Divychky in Kiev region, Ukraine, October 21, 2016. (Photo by Valentyn Ogirenko/Reuters)

A Mai-Mai rebel soldier shows off his guns at a checkpoint near the Mugunga refugee camp in Zaire; 1996. (Photo by Carol Guzy/The Washington Post)