An emu runs to escape an approaching wildfire as it burns near Potero, California, U.S. June 20, 2016. (Photo by Mike Blake/Reuters)

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.

Paramedics carry an injured woman out from a subway station after a rush-hour subway train derailment, to be transported by a medical helicopter in Moscow, Russia, on Tuesday, July 15, 2014. A rush-hour subway train derailed in Moscow Tuesday, killing 20 people and injuring at least 150, emergency officials said. Several cars left the track in the tunnel after a power surge triggered an alarm, which caused the train to stop abruptly. (Photo by Ivan Sekretarev/AP Photo)

Wounded people walk after clashes with riot police in central Kiev February 18, 2014. Ukrainian riot police advanced on the heart of 12-week-old protests against President Viktor Yanukovich on Tuesday and security forces set a deadline to end disturbances after at least five protesters were reported killed in a day of clashes. (Photo by Vlad Sode/Reuters)

Chelsea Hughes, 25, sings at the first annual Underwear Karaoke, an event that pairs two common fears: being seen in your underwear and singing in public, in Los Angeles, California March 12, 2015. (Photo by Lucy Nicholson/Reuters)

In this photo provided by Rolex, jury members inspect a 1933 Duesenberg SJ Brunn Riviera Convertible Sedan owned by John D. Groendyke at the Rolex Monterey Motorsports Reunion during Monterey’s Classic Car Week, Sunday, August 17, 2014, in Carmel, Calif. (Photo by Tom O’Neal/AP Photo/Rolex)

Isabella Busse, 6, walks through floodwater near the Seal Beach Pier during a storm in Seal Beach, Calif., Sunday, January 22, 2017. The heavy downpour on Sunday drenched Orange County in one of the heaviest storms of the year. Fast-moving floodwaters swept through California mountain communities and residents fled homes below hillsides scarred by wildfires as the third in the latest series of storms brought a deluge Sunday and warnings about damaging mudslides. (Photo by Ana Venegas/The Orange County Register via AP Photo)

The Founders' Award winner, Downey Rose Float Association “Exploring the Everglades” float, moves through 127th Rose Parade in Pasadena, California January 1, 2016. (Photo by David McNew/Reuters)