Ans. When large rocky coastlines flow into the sea, an arch is formed with a gate-like look, a coastal arch. It is all mother nature's process for the disposition of rocks or causing a hollow cave parting ocean or sea into two. When powerful waves of ocean strike a rock, the weaker section is displaced, which further causes an open area in a rock. The waves start braking through the right headland, forming an arch-like gate. Usually, this rock’s disposition by huge ocean waves creates two different coastal landforms- a natural bridge and a gate. It is not a single day process but takes thousands and millions of years to develop a natural arch. Further erosion of these arches can lead to the formation of massive columns, which are sea stacks.