世界匪夷所思的自然現象:美國風帆石
When visitors stumbled upon scores of heavy stones that appeared to have moved across the dried lake bed of Racetrack Playa in California’s Death Valley National Park, leaving a tell-tale trail in their wake, scientists were baffled. How had so many boulders, some weighing 300kg, moved as much as 250m across this remote part of the valley, asks Quora user Farhana Khanum?
在加利福尼亞死亡谷國家公園，遊客無意中發現幾十塊大石頭在賽馬場鹽湖的幹湖牀上移動，留下神祕的尾波，科學家們也不知道如何解釋這一現象。Quora用戶法爾哈納•哈姆問道，這些卵石中有的重達300千克，它們是怎麼做到移動近250米到達峽谷的另一頭？
Adding to the mystery, some trails were gracefully curved, while others were straight with sudden shifts to the left or right. Who, or what, had moved the stones? A slew of theories emerged, from magnetic fields to alien intervention to dust devils to pranksters.
更爲神祕的是，一些痕跡竟然還有優美的弧度，還有一些痕跡是直線狀，但伴有突然左拐或右拐的印記。到底是誰還是什麼東西在移動這些石頭？從磁場作用到外星人事件到塵捲風再到惡作劇，人們對此猜測不斷。
It took a NASA scientist to crack the case. In 2006, Ralph Lorenz developed a kitchen table model using a small rock frozen in an inch of water in a Tupperware container to demonstrate ice shove, the phenomenon behind the mysterious sailing stones.
一位美國航空航天局(NASA）的科學家解開了謎團。2006年，拉爾夫•洛倫茨發明了一個餐桌模型——在保鮮盒裏裝一英寸高的水，放入小石粒並將水冰凍。用這個模型解釋冰壅，神祕的風帆石背後的真相。
In winter, Racetrack Playa fills with water and the lakebed’s stones become encased in ice. Thanks to ice’s buoyancy, even a light breeze can send those frozen boulders sailing across the muddy bottom of the lakebed. Stones with rough bottoms leave straight tracks, while those with smooth bottoms drift and digress. Warmer months melt the ice and evaporate the water, leaving only the stones and their mysterious trails.
一到冬季，賽馬場鹽湖漲滿了水，而湖牀裏的石頭則被冰封起來。由於冰有浮力，即使是一陣輕風也能幫扶着冰凍卵石一直劃過湖牀的泥濘底部。底部不光滑的石頭會留下直線劃痕，而底部光滑的石頭則會漂移，偏離原路。天氣開始轉暖時，冰雪消融，水汽蒸發，留下的只剩那些風帆石和它們神祕的移動軌跡。
Visitors can see these sailing stones in a few locations, including Little Bonne Claire Playa in Nevada and most famously, Death Valley’s Racetrack Playa.
在內華達州的小女僕克萊爾鹽湖以及著名的死亡谷賽馬場鹽湖等地方都可以發現這些風帆石。
