splinter off and develop into a much more specialized discipline, characterized by the development of a wide assortment of flat-ground tricks. As a result of the "vert" skating movement, skate parks had to contend with high liability costs that led to many park closures. In response, vert skaters started making their own ramps, while freestyle skaters continued to evolve their flatland style. Thus, by the beginning of the 1980s, skateboarding had once again declined in popularity. 1980s This period was fueled by skateboard companies that were run by skateboarders. The focus was initially on vert ramp skateboarding. The invention of the no-hands aerial (later known as the ollie) by Alan Gelfand in Florida in 1976, and the almost parallel development of the grabbed aerial by George Orton and Tony Alva in California, made it possible for skaters to perform airs on vertical ramps. While this wave of skateboarding was sparked by commercialized vert ramp skating, a majority of people who skateboarded during this period did not ride vert ramps. As most people could not afford to build vert ramps, or did not have access to nearby ramps, street skating increased in popularity. Freestyle skating remained healthy throughout this period, with pioneers such as Rodney Mullen inventing many of the basic tricks that would become the foundation of modern street skating, such as the "Impossible" and the "kickflip". The influence that freestyle exerted upon street skating became apparent during the mid-1980s; however, street skating was still performed on wide vert boards with short noses, slide rails, and large soft wheels. In response to the tensions created by this confluence of skateboarding "genres", a rapid evolution occurred in the late 1980s to accommodate the street skater. Since few skateparks were available to skaters at this time, street skating pushed skaters to seek out shopping centers and public and private property as their "spot" to skate. (Public opposition, in which businesses, governments, and property owners have banned skateboarding on properties under their jurisdiction or ownership, would progressively intensify over the following decades.) By 1992, only a small fraction of skateboarders continuing to take part in a highly technical version of street skating, combined with the decline of vert skating, produced a sport that lacked the mainstream appeal to attract new skaters. During this period, numerous skateboarders—as well as companies in the industry—paid tribute to the scenes of Marty McFly skateboarding in the film