Term
| Describe the discovery of the continental drift theory, including the concept of Pangaea, plus list evidence supporting this theory |
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Definition
| Alfred Wegener stated that 200 million years ago all of the continents were joined together in one super continent called PANGAEA. Then this super continent started breaking into smaller continents, which then drifted to their present positions. (this is still happening today). |
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Term
| List Evidence to support the drift theory |
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Definition
1. Fit of the Continents
The continents fit together like a jigsaw puzzle.
2. Fossil Evidence
The bones of ancient creatures like the Mesosaurus ( a presumably aquatic, snuggle-toothed reptile) lived in both continents S. America and Africa.
3. Rock Types and Structures Match
Mountain belts disappear of New Foundland and reappeared in Greenland and North America.
4. Paleoclimatic - Ancient Climates
- Glacier debris and ice striation in Southern continents like Africa (now tropical). |
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Definition
Divergent Boundaries
Plates move apart, resulting in upwelling of magma, creating new sea floor .
- Seafloor spreading has created the floor of the Atlantic Ocean during the past 200 million years. The rate of spreading ranges between 2 and 10 cm. per year. |
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Definition
| Downfalted valleys created by plate spreading within a continent. eg. East Africa Rift Valley. |
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Definition
| Plates come together and one plate subducts under the other |
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Definition
Ocean plate subducts under continental plate. Deep ocean trench and volcanic arcs are created.
eg. Cascade Range and Andes Mountains. |
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Definition
| Island Arcs are created. eg. the Aleutian, Mariana, and Tonga were created this way. |
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Definition
| Mountain Ranges are created. When India crashed into Asia the Himalayas were created. |
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Definition
Plates slide past one another
eg. San Andreas fault. |
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Definition
| Earth's magnetism periodically reverses and this leaves a "tape recording" in the sea floor rocks proving sea floor spreading. |
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Term
| Global Distribution of Earthquakes |
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Definition
| Ring of Fire, Circum Pacific. Global distribution of earthquakes and their close association with plate boundaries. |
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Definition
| 30 years ago the Glomar Challenger put a drill down the ocean floor. The thickest sediments were adjacent to the continents (oldest), while thinnest were near Mid-Atlantic ridge (youngest). |
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Definition
The existence of Island groups that formed over hot spots provide a way to trace the direction of plate motion.
e.g.: Hawaiian Islands |
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Definition
Magma is melted rock, it has gases trapped in it.
If you vent the gases out of magma it turns into lava. |
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Definition
| Sticky, it has lots of granite. This magma creates violent eruptions |
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Definition
| Like water, basaltic . These occur in Hawaii. They are gentle flows of lava |
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Definition
| Mountain formed by lava or pyroclastic. |
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Definition
| Located at the summit of many volcanoes. It is a steep walled depression. |
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Definition
Large depression caused by collapse or ejection of summit of a volcano.
e.g. Crater Lake, Oregon with Wizard Island (has a volcano on top of it). |
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Definition
"Glowing avalanches".
e.g. Mount Pelee - Martinique (Caribbean Islands). Destroyed the city of St. Pierre. Killed 28.000 people. |
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Definition
| Mudflows down slopes of volcano caused by heat melting snow caps. |
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Definition
Broad slightly domed structures are formed by fluid basaltic lava flows.
e.g. Hawaii. Mauna Loa and Kilauea |
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Definition
Build of pyroclastic fragments
They have a steep angle of 30-40 degrees.
Small in size and form as parasitic cones on or near larger volcano.
e.g. Paricutin in Mexico which erupted in 1943. |
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Term
| Composite Cones (Strato volcanoes) |
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Definition
They are earth's most picturesque volcanoes formed of viscous andesitic lavas and ejected pyroclastics in alternate layers.
e.g. Mount Fujiyama (Fuji in Japan) . All Cascade Range volcanoes are of this type.
Violent like Mount Vesuvius and Mount St. Helens, Washington (1980) |
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Definition
| Mountain formed by lava or pyroclastic. |
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Definition
| Tube from surface into magma chamber. |
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Definition
Eroded Volcano
example: Shiprock, New Mexico |
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