In many cases you will be given a cave location that utilizes less than five quarter-sections, perhaps only four or three. A tool is often used to assist cave plotters. Usually it can be purchased from places such as the DGLS building in Rolla. The cost is minimal. Longitude lines are thus measured by how far they are east or west of the Greenwich meridian.
E ach full unit of either latitude or longitude is called a degree.
There are 90 degrees latitude from the equator to the north and 90 to the south. There are 180 degrees from Greenwich to the east and west. The 180th meridian east or west, of course, is the same line and is the international date line. Remember, although latitude degrees, minutes and seconds are always the same size, longitude lines grow closer together as you go north, and are thus not the same size. Using the grid or ruler, you can determine how far apart the longitude lines are at the edge of a topo map.