Differences in water density, resulting from the variability of water temperature (thermo) and salinity (haline), also cause ocean currents. This process is known as thermohaline circulation. In cold regions, such as the North Atlantic Ocean, ocean water loses heat to the atmosphere and becomes cold and dense.
A grid made up of longitude and latitude lines to precisely locate specific locations. The compass rose indicating the cardinal directions of North, South, East, and West as it relates to the map. The scale compares the distances on the map to actual distances (i.e. 1 inch = 10 miles).
During an earthquake, the first waves to be detected are the p-waves where p stands for (primary). Those are then followed by the compressional s- or secondary waves. Finally come the surface waves, which are the most destructive of the three.
