Plates at our planet's surface move because of the intense heat in the Earth's core that causes molten rock in the mantle layer to move. It moves in a pattern called a convection cell that forms when warm material rises, cools, and eventually sink down. As the cooled material sinks down, it is warmed and rises again
Yellow lines means that roads are merging and there's going to be traffic coming, so it's a warning to be cautious and to join the merged road. It's usually a warning to people that are going at a high speed in their vehicle. So merging majorly helps prevent an accident.
