death valley has many famous and unusual geographical features. some of these features include sand dunes, salt flats, colorful rocks, and tall mountains. large parts of death valley are below sea level. one feature, named badwater basin, is the lowest place in north america. it is below sea level. the salt flats are another famous feature in death valley. salt flats are very unusual. they are large, flattened areas where the surface of the ground is covered by salt instead of dirt. the salt that makes up a salt flat can be many inches or centimeters deep. the salt flats were created because thousands of years ago, death valley was underwater. death valley was covered by a lake that was named lake manly by geologists (scientists who study the earth). lake manly used to be very large, but changes in the weather caused the rivers that brought water into the lake to dry up. after a long time, the water in lake manly began to dry up too. as the water dried, it left behind all the minerals that the rivers had brought to it along with their water. as these minerals dried, they created a crust (a brittle outer layer) of salt and other minerals on top of the dirt. many lakes and seas in other parts of the world dried up in the same way.