GLY170-101_Stamper_Eddie_Part III Homework
docx
keyboard_arrow_up
School
Marshall University *
*We aren’t endorsed by this school
Course
170
Subject
Geology
Date
Dec 6, 2023
Type
docx
Pages
1
Uploaded by BaronMask27113
1.
Why does an oceanic plate subduct beneath a continental plate?
a.
Continental crust is thicker and more buoyant than oceanic crust, making oceanic crust
more likely to subduct than continental crust.
2.
Why are the Olympic and Cascade mountain ranges so different?
a.
The Olympic mountain range is the product of crustal deformation, as some hard ocean
crust and sedimentary layers scraped off the top of the Juan dee Fuca Plate and formed
the Olympic Mountains. Meanwhile, the Cascade mountain range is more volcanic, as it
lies above a portion of the Juan de Fuca Plate that is 50 miles deep; it’s so hot at that
depth that fluids begin to sweat from the oceanic crust and melts rock in their path which
produces magma.
3.
Are the Olympic Mountains getting higher or lower?
a.
Neither – the amount of uplift caused by layers added to the base of the mountains by the
Juan de Fuca Plat as it subducts is roughly balanced by erosion due to win, water, and
ice.
4.
Why are subduction zone volcanoes so steep?
a.
Silica causes magma to thicken, and the magma beneath mountains such as Mount
Rainier and Lassen Peak is highly concentrated with silica, causing the lava to be thick,
not flow very far, and stick to the sides and make a steep composite volcano.
5.
Why do subduction zone volcanoes sometimes explode?
a.
Magma in subduction zones are rich in silica, which causes the magma to be thick and
not let gas escape. As pressure builds with gases being trapped by the thick magma,
explosions will occur once the pressure is released.
6.
Why is a devastating earthquake expected in the Pacific Northwest?
a.
The Pacific Northwest is expected to have a devastating earthquake because the last
large earthquake occurred 300 years ago, and due to the stress building between the
Juan de Fuca and North American plates earthquakes would be expected to take place
every 200-800 years.
7.
Why is the rock in the parks in the Sierra Nevada Mountains so good for climbing?
a.
Sierra Nevada Mountains formed above a subduction zone which stopped subducting
about 20 million years ago. Since then, the volcanoes have eroded away and exposed
the rocks of the magma chambers below. These rocks have strong cracks and mineral
crystals that are easily grasped and ideal for climbing.
8.
How did the Appalachia Mountains form?
a.
From about 400 to 300 million years ago, the Iapetus Ocean gradually closed during
subduction. In the process, volcanic islands, continental fragments, and finally the African
continent collided with the ancient continental margin of North America to form the
Appalachia Mountains.
9.
How high were the Appalachians at the time of collision?
a.
At the time of collision, the Appalachians were, in places, as high as Mount Blanc in the
Alps (15,781 feet; 4,810 meters) or Mount Everest in the Himalayas (29,035 feet; 8,850
meters).
10.
How deep were the metamorphic rocks that are now exposed at the surface in the Appalachians?
a.
Metamorphic rocks now exposed at the surface of the Appalachians were 5 to 15 miles
(10 to 25 kilometers) below the surface.
Discover more documents: Sign up today!
Unlock a world of knowledge! Explore tailored content for a richer learning experience. Here's what you'll get:
- Access to all documents
- Unlimited textbook solutions
- 24/7 expert homework help