As all the blocks cascaded they hit another block, but the last block had enough room to slide forward slightly, which in turn allowed the one that landed on it to drop and move forward slightly, which in turn allowed the one before it to drop down and move forward slightly, and so on.
As all the blocks cascaded they hit another block, but the last block had enough room to slide forward slightly, which in turn allowed the one that landed on it to drop and move forward slightly, which in turn allowed the one before it to drop down and move forward slightly, and so on.