Why is the distance between 2 meridians at the north pole 0 miles

The distance between two meridians, or all meridians if you will, is 0 miles at the North Pole, as well as the South Pole, and this is due to the form of the Earth. Because our planet is ecliptic, and the meridians are going in a north-south direction, the poles are their starting/ending points, so there's no distance between them, but as they come towards the Equator, they spread, and the distance between them grows, being the biggest at the Equator itself, and as they start to move away from the Equator the distance between them shrinks until they get to the pole where they all merge again.

sediment layers stop spreading when they reach a barrier or they run out of sedimentary material. lateral spreading is the movement of gently to steeply sloping, saturated soil deposits caused by earthquake-induced liquefaction. i hope this . : )