Activity 1 – Where are the Volcanoes?
Background Information
The USGS map This Dynamic Planet is a world map of volcanoes, earthquakes, and plate tectonics. The bottom of the map
contains excellent background information that will help you prepare for the activity.
It includes an overview of the theory of plate tectonics. It also describes volcanism at plate boundaries (convergent plate boundaries and divergent plate boundaries) and within the interior of plates (hot-spot volcanism).
The map uses triangles to show volcanoes. Each type of triangle represents an age
range of recent activity. Red lines depict
volcanism at divergent boundaries. Most
volcanism occurs beneath the ocean at mid-ocean ridges. Thus, the triangles represent individual volcanoes, while the red lines depict linear trends of volcanism. The colors on the map show depth within oceans and elevation of land. The shallower depths over the mid-ocean ridge are clearly seen from the lighter blue colors (shallower depth) on the ocean floor.
Terms that you will encounter on the USGS map that may be unfamiliar to you include: Holocene: a division of geologic time; an epoch of the Quaternary period, from the end of the Pleistocene, about 8000 years ago, to the present time.
Fumarolic activity: this refers refers to fumes or vapors that are emitted from a hole or fissure in a volcano.
Latitude: used to describe north–south
location, and longitude used to describe
east–west location. Lines of latitude on a
map are called parallels because they run
parallel to one another. Latitude ranges
from 0° at the Equator to 90° north latitude at the North Pole and 90° south latitude
at the South Pole. Lines of longitude are known as meridians. Meridians are farthest apart at the Equator and converge at the poles. Meridians “start” at the prime
meridian at Greenwich, England (zero degree
longitude) and increase to 180° east and
west longitude. Each degree of latitude or longitude can be subdivided into 60 minutes, and each minute into 60 seconds. These
minutes and seconds of arc have nothing to do with the minutes and seconds of time.
The USGS map This Dynamic Planet is a Mercator projection. Imagine wrapping a cylindrical sheet of paper around a spherical globe, and projecting the lines of latitude
and longitude onto the paper (you might demonstrate this with a baseball and sheet
of paper). Mercator projections are most accurate where the map touches the globe. They create distortions that increase toward the poles, and they typically do not show areas near the poles.
If you want students to add current eruptions to their maps of historically active volcanoes, check out the listings at the Volcano World Web Site. Visit the EarthComm web site for the current address.
The EarthComm web site also contains a variety of links to web sites that will help you deepen your understanding of content and prepare you to teach this activity.
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