Using the power of Google Earth, GeoTours take you on flyovers of key locations discussed in the text.
StudySpace student website and ebook icons in each GeoTour connect your to the text and online review materials.
Dialogue boxes accompanying each site include text, figures, photos.
|
|
Geotour 5: Volcanic Features
Shield Volcanoes
|
| 1a. Shield volcanoes have a characteristic shape like a concave-down warrior’s shield, in part because they are predominantly composed of low viscosity basaltic lava.
Check and double-click the placemarks for Problem 1a in the Problem 1 folder to fly to Mauna Loa on the Big Island of Hawaii in the Hawaiian Islands. Turn on the “Mauna Loa contour map” in the Problem 1 folder. The brown lines are contours (lines of equal elevations). Use the Measuring Tool to determine the horizontal distance between the placemarks for Problem 1a (use feet as your units) and then subtract the elevations for each placemark from the contour map to determine the relief. Find the slope of Mauna Loa using the following formula (this value is representative for many shield volcanoes): slope angle = arctan (relief/horizontal distance).
|
|
|
| 1b. Check and double-click the placemarks for Problems 1b-i, -ii, and -iii. The basaltic lava flows weather according to their age (darker is younger). Place the three lava flows in chronologic order from youngest to oldest.
|
|
|
| 1c. Check and double-click placemark Problem 1c. Here, the fluid basaltic lava flows have flowed from Kilauea’s eruptive vents over a steep cliff on their way to the ocean. Such a cliff is called a pali. Turn on the “Hawaiian Island Overlay” and determine what the pali represents.
|
|
|
| 1d. Check and double-click placemark Problem 1d. Even from this distance, you can see the ropey flow patterns of this distinctive type of basaltic lava flow. What is it called?
|
|
|
| 1e. Check and double-click placemark Problem 1e to fly to the summit of Mauna Kea. A series of small parasitic volcanoes dot the landscape. These types of volcanoes often erupt during the latter stages of activity for the larger volcano. What type of volcanoes are they?
|
|
|
Composite Cone Volcanoes
|
| 2a. Composite cones (or stratovolcanoes) have the characteristic symmetrical shape most commonly associated with volcanoes. They are typically comprised of layers of andesitic lava and pyroclastic materials. Because of their composition, these volcanoes tend to be very explosive.
Check and double-click the placemarks for Problem 2a to fly to Mt. Saint Helens in the Cascade Range of western Washington. Turn on the “Mt. Saint Helens contour map” in the Problem 2 folder. The brown lines are contours (lines of equal elevations). Use the Measuring Tool to determine the horizontal distance between placemarks for Problem 2a (use feet as your units) and then subtract the elevations for each placemark from the contour map to determine the relief. Find the slope of Mt. Saint Helens using the following formula (this value is representative for many composite cone volcanoes): slope angle = arctan (relief/horizontal distance).
|
|
|
| 2b. Check and double-click the placemarks for Problem 2b and turn on the “Mt. St. Helens Volcanic Features” map. Use the Measuring Tool to determine the greatest distance (in km) affected by the lateral blast of the May 18, 1980 eruption (measure between the placemarks for Problem 2b).
|
|
|
| 2c. Check and double-click placemark Problem 2c to fly to the town of Bronte near Mt. Etna volcano on the island of Sicily. You are a geologic consultant for a company that is considering building a factory in Bronte. Based on your previous work on Mt. Saint Helens and on observations that you make as you fly over the region, decide if it is wise to build there.
|
|
|
| 2d. Check and double-click the placemarks for Problem 2d to fly to Mt. Vesuvius in Italy and view the “Pompeii Pyroclastic Surge Flyover.” Use the Measuring Tool to determine the distance (in km) from Mt. Vesuvius to the excavated ruins of the city of Pompeii (which was buried by volcanic ash and pyroclastic material from Mt. Vesuvius during the eruption of 79 C.E.) If a nuée ardent (pyroclastic surge) accompanies the next eruption of Mt. Vesuvius and it travels at 300 km/hr, how many minutes would it take to reach the site of ancient Pompeii?
|
|
|
| 2e. Check and double-click the placemark for Problem 2f to fly to Crater Lake, OR and turn on the “Crater Lake, Or map”. The composite cone Mt. Mazama explosively erupted ~7000 years ago. Not only was most of the cone blown away, but a large depression was created as the material collapsed into the evacuated magma chamber. What is this depression called? Note the parasitic cinder cone (Wizard Island) that has developed.
|
|
|
Cinder Cone Volcanoes
|
| 3a. Cinder cones are the smallest volcanoes and often are found parasitic on larger volcanoes. They typically erupt pyroclastic materials, but they also commonly have small lava flows that emit from the base of the cone during the latter parts of their short-lived eruptive “lives”.
Check and double-click the placemarks for Problem 3a to fly to SP Mountain, AZ. Turn on the “SP Mountain contour map” in the Problem 3 folder. The brown lines are contours (lines of equal elevations). Use the Measuring Tool to determine the horizontal distance between placemarks for Problem 3a (use feet as your units) and then subtract the elevations for each placemark from the contour map to determine the relief. Find the slope of SP Mountain using the following formula (this value is representative for many cinder cone volcanoes): slope angle = arctan (relief/horizontal distance).
|
|
|
| 3b. Check and double-click the placemark for Problem 3b to fly to Menan Buttes, ID. These cinder cones are asymmetric (much like other cinder cones). What causes the asymmetry?
|
|
|
| 3c. Double-click the placemarks for Problem 3c to fly to Sunset Crater, AZ. To get a sense of scale for cinder cones, use the Measuring Tool to determine Sunset Crater’s width (in km).
|
|
|