sentence1: This winter's ski season in Europe and the US has been stunning — the snow arrived early, fell in heaps, and is still falling in many places. Only last weekend an extraordinary 4ft snowfall across Colorado and Wyoming left hundreds of drivers stranded on freeways and brought down power lines. But the future of skiing in many resorts hangs in the balance. The world's highest ski run has closed after running out of snow over several years — the Chacaltaya ski area in Bolivia stood at 5,300m (17,388ft) on a glacier. Skiing was established at Chacaltaya 70 years ago with Lake Titicaca on the horizon, and about 14 years ago could boast a ski run 12m (40ft) deep in snow. Bolivia even had its own Winter Olympics team until 1992.
sentence2: Lake Titicaca is a lake located on the border between Bolivia and Peru.