<span>Sinkholes, especially like the one that occurred in Mexico City, are often sign that the water reservoir is being depleted. Usually, the water underneath the ground helps stabilize it, however if there is suddenly open space or a cavern, it can collapse on its self causing a sink hole. This could also happen from fracking and drilling.</span>
Why doesn't it follow a straight line? Why do we need it? The International Date Line serves as a beginning and ending point for the world's time zones. The line moves in jagged directions through the Pacific Ocean in order to keep certain island nations together.
