At what altitude is Class E airspace depicted as dashed magenta on sectional charts?

Class E airspace depicted as dashed magenta on sectional charts is indicative of airspace that extends from the surface upward. This designation shows that the airspace begins at ground level (the surface) and is primarily utilized for airports that do not have a control tower. The dashed magenta lines signify that pilots in the vicinity need to be aware of the Class E airspace even when they are operating at lower altitudes.

Class E airspace can also exist at 1,200 feet AGL and 700 feet AGL, but when it is represented with the dashed magenta lines, it specifically indicates that the airspace begins at the surface. This helps pilots understand where they are allowed to operate and what the airspace classifications mean as they navigate in the vicinity of these areas.