20 of the strangest natural phenomena in America

Susanne Pommer // Shutterstock As the fourth-largest country in the world, the United States has a vast assortment of picture-perfect natural scenery to flaunt. From the Alaskan Tundra to the Gulf of Mexico, Niagara Falls to the Hawaiian Islands, the contrasts between the 50 American states and five territories are fascinating and sometimes enigmatic. Geological, physical, chemical, and biological phenomena have rational explanations, but some are so rare they seem to be a figment of a science fiction screenwriter’s imagination. Nonetheless, understandable or not, they do–unmistakably–indulge the senses. From features in national parks to regional quirks, Stacker compiled a list of 20 of the strangest natural phenomena in the U.S. Anyone hoping to catch a glimpse of these phenomena must remain mindful of the risks they face in the wilderness and also of the damage they could inflict on the environment. Government and community organizations manage the grounds where many of these natural happenings occur–and are often available to guide visitors through their journey. So, revel in that which only nature can offer, buckle up for a jaw-dropping adventure, and enjoy the ride. You may also like: 50 incredible photos of our oceans Death Valley’s sailing stones Paul Brady Photography // Shutterstock Death Valley National Park was established as a natural monument in 1933. Although its name could be more inviting, its beauty is undeniably unique. Its main attraction is the geological phenomenon known as the sailing stones–a mystery that kept scientists and explorers in awe for decades. In the early 2010s, time-lapse photographs and rigorous investigations uncovered the enigma. The rocks, ranging from weighing a few ounces to over 700 pounds, move every winter without human or animal intervention when the wind blows strong enough to slide them over thin sheets of melting ice. The ice melts and moves when exposed to warm morning sunlight, a process known as ice shove. Florida’s colorful swamp Kate Scott // Shutterstock When oils released by decaying vegetation drift into the pooled water of the Sunshine State’s wetlands, a rainbow-colored phenomenon decorates the scenery: Florida’s colorful swamp. The spots of oil slick reflect sunlight into trees and bushes, making them look multihued and vibrant. The natural spectacle can appear in any swamp and any time of the year, but it is rather notorious under a cloudless sunny sky and when humidity is at its highest. Lunar rainbows akphotography00 // Shutterstock Much rarer than rainbows but just as marvelous, moonbows or lunar rainbows can appear when the moon is in or near its full phase and positioned low in the sky, most likely an hour before sunrise or after sunset. As with rainbows, water droplets must be in the air–from waterfalls, rain, or breaking waves–on the opposite side of the light-reflecting celestial body for the iridescent visual phenomenon to happen. Great Smoky Mountains’ lightning bugs SIHASAKPRACHUM // Shutterstock Sometime between the third week of May and the third week of June, the beetle species, officially known as Photinus carolinus, will enter its mating season in the Great Smoky Mountains. Male fireflies synchronize their flashing lights so females can recognize them. The spectacle put on by millions of lightning bugs blinking simultaneously in the dark forest nights attracts hundreds of tourists who plan their visit several months in advance. Taos hum Sopotnicki // Shutterstock To this day, there is no agreement among the scientific community about why 2% of people hear a low-frequency hum in the small town of Taos, New Mexico, and its surroundings since the 1990s. The explanations for the mystery range from plain boring–such as tinnitus–to amusingly creative, like secret government mind control experiments. Real or not, it seems like the only way to find out if there is a humming sound in the historic Taos area is to pay a visit and formulate your own hypothesis. You may also like: Most popular historic sites in America Yellowstone’s geysers Susanne Pommer // Shutterstock The attractions of Yellowstone Park have been in the making for over half a million years. Geysers, hot springs, fumaroles, and mud pots result from the interaction between underground volcanic activity and groundwater. The superheated water of hot springs–trapped in channels leading to the surface–erupts when the steam in the inner layers of the volcanic caldera (where Yellowstone lays) lifts the cooler water in the upper layers causing the flashy phenomenon called geysers. The most famous performer of the geothermal show is Old Faithful, a highly predictable geyser that erupts every 45 to 100 minutes. Horsetail Fall in Yosemite Gregory B Cuvelier // Shutterstock Every summer night for almost a century, burning hot embers were poured from Glacier Point in Yosemite National Park down the cliff to the valley below. The 3,000-foot drop of incandescent coal put on a magnificent show that attracted growing crowds from 1872 to 1968. Nowadays, a natural spectacle evocative of the man-made fire has taken center stage: Horsetail Fall in Yosemite, an evanescent waterfall that sometimes–during the two last weeks of February–turns bright orange when backlit by the sunset gleam. Thor’s Well