What name is given to the 4 mile (6.4 km) stretch of Las Vegas Boulevard which is mainly in the unincorporated communities of Paradise and Winchester?
What is the name of the 3.5-mile-long (5,600 m), 5.5 km wide semi-circular scalloped precipice in the Grand Coulee in Washington, USA?
An unusual feature of which river is a submerged canyon and a waterfall parallel to the river instead of across it but seen for only half the year?
