Areas of equal elevation are connected by lines on a topographic map.

meridian

longitude

contour

latitude

Contour

Explanation:

These are just lines that follow the points on the map that contain the same elevation, and are not the lines that one sees drawn for finding particular locations on a projected flat surface of the Earth like meridians or parallels, that give us longitude and latitude of a place.

The topographic lines are actually trying to represent (give an image of) the third dimension (elevation) in a two dimensional chart.

3.2x10^7

answer: the metamorphic rocks are formed when they are exposed to high pressure and high temperatures. this happens when one of the earth's plates comes in contact with the other plate by traveling in opposite directions, straight into each other or slipping under one another. the friction that is caused by this activity results in   melting of rocks and when it cools they are known as metamorphic rocks. this process needs a controlled amount of pressure and temperature otherwise it may turn into magma.