What is the origin of 'sleep tight'?
Read moreOne of the mysteries of the English language finally explained.
A deep gorge in Arizona, formed by the Colorado River. It is about 440 km (277 miles) long, 8 to 24 km (5 to 15 miles) wide, and, in places, 1,800 m (6,000 ft) deep. The area was designated a national park in 1919.