While earthbenders like being rooted to the ground, with some like Toph being unable to see in the air, they can quickly move rock beneath them and launch them several tens of feet into the air, whether to catch airborne opponents or to travel faster. Toph and Bumi did this during the battle at Wulong Forest and the liberation of Ba Sing Se, respectively. Bolin has shown to be able to launch himself into the air with Earthbending, as was seen when he escaped the Earth Queen's palace.

Example:

stomp the ground with your foot or something