Inquiring Further
1. Eruptions near your community
The EarthComm web site, will direct students to the portion of the Volcano World web site that lists hundreds of historically active
volcanoes. Data on the relevant Volcano World web page are broken down by
country and state, but the USGS map does not show names or boundaries of states
or countries. Thus, students will need to consult a map of the United States or North America that shows latitude and longitude (a wall map will work). Students should obtain the coordinates from their data table (from the investigation), identify the state or country, search the Volcano World web site by state or country, and then confirm the coordinates and volcano name. Once they have identified the volcano, they can move through the Volcano World web site to do further research.
2. Volcanoes and the water on Earth (the hydrosphere)
Research to find answers to the following questions:
- How do volcanoes at mid-ocean ridges affect the temperature of seawater?
In the immediate vicinity of a submarine volcano, the seawater is strongly heated, but in the context of the entire ocean, this effect is small. The temperature of the oceans is controlled almost entirely by the formation and sinking of cold water at the surface at high latitudes, and by heating of the water at the surface at low latitudes. - How do volcanoes change the chemistry of seawater?
Hot springs at mid-ocean ridges release enormous quantities of dissolved material, derived from cooling magma, into the oceans. The overall circulation of the oceans then disperses these dissolved materials throughout the world’s oceans. - How does seawater affect the composition of volcanic rock that is formed at the mid-ocean ridge?
As the lava is emitted from the volcanic vent, it is chilled by the cold seawater, and it crusts over rapidly. As it oozes out from cracks and fissures, it tends to form crusted blobs, which break off and fall to the sea floor. These are called pillows. Pillow lavas are considered to be excellent evidence of underwater volcanic activity. - Would volcanoes affect a small body of seawater, such as the Red Sea, the same way as a large ocean like the Atlantic?
In the same way, but more strongly, because of the smaller volume of water that
is affected. - Can a change in the volume of volcanic rock formed at mid-ocean ridges change
sea level?
It might seem that an increase in the volume of volcanic rock would add to the volume of the mid-ocean ridges and that this would raise sea level. This effect is offset, however, by a decrease in the volume of material beneath the ridge, which would tend to lower the ridge. A different, and indirect, effect would be more important: at times of increased mid-ocean-ridge volcanism, the temperature of the rocks in and beneath the mid-ocean ridges increases, and the thermal expansion of the entire mass of rocks means higher mid-ocean ridges. The higher ridges cause a rise in sea level. By this effect, sea level has varied by as much as hundreds of meters through geologic time.
These are questions for further research that will help students to develop a better understanding of the interactions between volcanoes and the hydrosphere.
Direct students to the EarthComm web site to help them get started with their research. |