People visit the Danxia National Geological Park in Zhangye, northwest China's Gansu Province, March 24, 2020. Boasting a unique type of geomorphology formed from red-colored sandstones and characterized by steep cliffs, the Danxia National Geological Park reopened to the public under strict measures to fight against the COVID-19. (Xinhua/Zhang Zhimin)

Aerial photo taken on March 24, 2020 shows a view of Danxia landform at Danxia National Geological Park in Zhangye, northwest China's Gansu Province. Boasting a unique type of geomorphology formed from red-colored sandstones and characterized by steep cliffs, the Danxia National Geological Park reopened to the public under strict measures to fight against the COVID-19. (Xinhua/Fan Peishen)

Aerial photo taken on March 24, 2020 shows a tourist bus at the Danxia National Geological Park in Zhangye, northwest China's Gansu Province. Boasting a unique type of geomorphology formed from red-colored sandstones and characterized by steep cliffs, the Danxia National Geological Park reopened to the public under strict measures to fight against the COVID-19. (Xinhua/Zhang Zhimin)

Aerial photo taken on March 24, 2020 shows a view of Danxia landform at Danxia National Geological Park in Zhangye, northwest China's Gansu Province. Boasting a unique type of geomorphology formed from red-colored sandstones and characterized by steep cliffs, the Danxia National Geological Park reopened to the public under strict measures to fight against the COVID-19. (Xinhua/Fan Peishen)

Aerial photo taken on March 24, 2020 shows people visit the Danxia National Geological Park in Zhangye, northwest China's Gansu Province. Boasting a unique type of geomorphology formed from red-colored sandstones and characterized by steep cliffs, the Danxia National Geological Park reopened to the public under strict measures to fight against the COVID-19. (Xinhua/Fan Peishen)