Complex sentence: The Transverse Ranges forms the perimeter of a series of basins that begins with the Santa Barbara Channel on the west end, and moving eastward there are the Ventura Basin, San Fernando Valley, and the San Gabriel Basin.
Split into simpler sentences: The Transverse Ranges form the perimeter of a series of basins that begins with the Santa Barbara Channel on the west end. Moving eastward, there is the Ventura Basin, the San Fernando Valley, and the San Gabriel Basin.