Phillips, Kevin Reed, and the Z-Boys, started to skate the vertical walls of swimming pools that were left empty in the 1976 California drought. This started the vert trend in skateboarding. With increased control, vert skaters could skate faster and perform more dangerous tricks, such as slash grinds and frontside/backside airs. This caused liability concerns and increased insurance costs to skatepark owners, and the development (first by Norcon,then more successfully by Rector) of ...
http://www.youtube.com/watch?v=mxisxRLs_ek&hl=en