Check Your Understanding
1. Scientists noted a mid-ocean ridge made of volcanic rock, and have observed the volcanoes using deep-sea submersibles.
2. The Ring of Fire is a pattern of volcanoes that form around the margins of the Pacific Ocean where plates slide down beneath the continents.
3. Most volcanoes on land form at the edges of continents and in island chains along the edges of the Pacific Ocean’s Ring of Fire. Volcanoes also occur on land in rift valleys and at hot spots.
4. Rift valleys form where two parts of a plate move apart from one another. When the plate is stretched, it breaks. The main break opens up to form a rift valley.
5. Hot spots are stationary sources of rising magma from beneath a plate. As the plate moves over the hot spot, a string of volcanoes is formed. A famous hot spot is the Hawaiian Islands, where a hot spot created a chain of volcanoes in the Pacific Ocean.
6. The horizontal scale increases with latitude in that one centimeter on the map equals a greater distance on Earth at higher latitudes than it does at lower latitudes. This results from the Mercator projection, which distorts the map more and more toward the poles. Looking down at the North Pole on a globe reveals that lines of longitude converge at the poles. On the Mercator projection, however, the lines of longitude are equally spaced from the Equator to the poles. |