=== Revenge and the Tour de France ===
Every July, bicyclists competing in the Tour de France speed more than 2,100 miles through the French countryside. They climb torturous mountain roads and rush downhill at speeds exceeding seventy miles per hour. Although testing strength, skill, and endurance, was part of the original plan for the Tour, the main motive behind creating the race was a grudge. In 1899, the editor of France’s largest sports newspaper, Le Vélo, wrote an article criticizing the wealthy industrialist Albert de Dion. De Dion, who had been an advertiser in Le Vélo, retaliated by starting his own sports newspaper, L’Auto. He aimed to outsell Le Vélo and put it out of business; therefore, L’Auto didn’t sell. At the time, sports newspapers sponsored their own bicycle races and reported on them to boost sales. In this tradition, de Dion’s editor proposed that L’Auto stage its own race. To make it distinctive, the race would be more difficult and longer than any before. It would be a challenging race that started in Paris—a tour of France. The hope was that people would buy the paper each day to follow the action. Leading up to the first Tour, L’Auto offered: 20,000 francs in prize money. The winner would get 3,000 francs; the rest of the money would be shared among the other top finishers. Soon sixty cyclists had signed up. The first inaugural Tour started on July 1, 1903. It took eighteen days and covered 1,508 miles, starting and ending in Paris. Of the sixty cyclists, only twenty-one completed the course. For the race’s end, thousands of spectators lined the streets of Paris to watch Maurice Garin cross the finish line first. L’Auto rushed out a special edition to cover the race’s finish, because it sold over 130,000 copies. The popularity of the Tour de France ensured the success of L’Auto and fabricated the demise of Le Vélo, which had gone out of business by 1904. De Dion had his revenge, and a world-famous race was born.
=== Walter Alvarez's Impact ===
While studying a canyon in Italy during the 1970s, a mystery caught the attention of geologist Walter Alvarez. At the K-Pg boundary, a band of rock that marks the end of the Cretaceous period and the start of the Paleogene, Alvarez recognized evidence of a large extinction. Fossils of many species of foraminifera (single-celled marine organisms) was abounding in the Cretaceous rock layer; however, in the Paleogene rock layer above, only one species remained. Alvarez later learned that the formation of the Paleogene fossils correlated to the mass extinction that wiped out over 70 percent of plants and animals, including the dinosaurs.
=== Mass Extinction ===
hat this mass extinction occurred... over millions of years. Alvarez thought the geologists... during that decade that this mass extinction... that this mass extinction... foraminifera fossils pointed to a more rapid extinction. They decided to test the clay layers to determine how long it took to form... At this point, the writer is considering adding the following accurate phrase: ... clay had an iridium level of nine parts per billion—six hundred times greater than that of the rock around it. Should the writer make this addition here?... Alvarez thought that such a staggering amount of iridium must have come from space... In 1980, Alvarez’s team published its theory: a huge meteorite had slammed into Earth. The dust and ash thrown into the atmosphere and blocking sunlight for months... For years, Walter Alvarez futilely searched in vain for an impact crater large enough to substantiate his theory... Then, in 1990, geoscientist Alan Hildebrand found evidence of an ancient asteroid impact that had occurred near Texas... This find led Hildebrand to two geophysicists who had discovered the Chicxulub Crater, a ninety-two-mile-wide crater off the coast of Mexico... The discovery encouraged Alvarez’s theory. A meteorite caused the K-Pg extinction.
=== Circles of the Sand ===
Aerial photos capture a mysterious phenomenon along Namibia’s arid coastline: thousands of round, bare patches of sandy earth pockmark a sea of stubbly grasses... But in 2013, ecologist Norbert Jürgens presented a promising new theory... Between 2006 and 2012, Jürgens traveled primarily from Hamburg, Germany... He consistently found moister soil within each circle than in the surrounding desert... The mystery of the circles lies not in the extra moisture but in the lack of vegetation... Jürgens believes that sand termites are the answer... Some scientists challenge Jürgens, arguing that his theory doesn’t explain the circles’ symmetry and even-spacing... But despite continued debate over the circles’ origin, no one disputes they’re positive affect on local wildlife.