SAN DIEGO CITY COLLEGE Geology 104, Earth Science, Fall 2018 Semester CRN: 88702
ID: 152994 • Letter: S
Question
SAN DIEGO CITY COLLEGE Geology 104, Earth Science, Fall 2018 Semester CRN: 88702 Instructor:Anna Evashko Ofce Hours: MW 9:00 a.m.-9:30 a.m. Telephone: 619-885-1249 Email Take Home Quiz #2 Student Name: ructions: All quizzes are open book/open notes. Each quiz is worth 10% ofyour grade. Complete this quiz and turn it in at the beginning of our next class meeting. Inst Section 1. True/False. Read the statement and indicate whether the statement is true or false by placing a "T if true and an "F" if false next to the statement in the space provided (T or F) 1. The volcanic activity found along the edges of the Pacific plate is 2. The Hawaiian Islands were formed by the subduction of the Pacific 3 Ash and lapilli are different sized pyroclastic material. 4. The eruptions of the stratovolcanoes in the Cascade Rage are referred to as the "Pacific Rim of Fire." Plate beneath the North America Plate explosive due to their viscous lava. 5. Repeated eruptions of relatively fluid lava from fissures can cause an 6. 7. 8. area to be covered by flood basalts. Shield volcanoes have very steep slopes. Pahoehoe lava appears smooth and ropy as it cools and forms rock. Basalt is the most common magma crupted along occanic rift systems. 9. A volcanic bomb is composed of dnanitie 10. The three types of volcanic cones are shield, composite, and fire. Page I of 5Explanation / Answer
1) True.
Pacific rim of fire is a belt of 452 volcanoes that occupy an area of 42000 km forming a horseshoe shaped ring on the basin of the pacific ocean. Almost 72% of the total number of volcanoes of the world occur here. This belt is the direct result of the plate tectonic activity. Eastern portion of the belt is created by the subduction of the Nazca Plate and the Cocos Plate beneath the South american plate, whereas the western portion is the direct result of the subduction of the Pacific plate along the Kamchatka Peninsula arcs.
2)False.
Hawaiian islands were created by the movement of the pacific plate over the hotspot on the pacific ocean. When the hot spot remained fixed, the plate moved over it to form the chain of islands.
3)True.
Pyroclastic materials are those solidified materials that are formed from the volcanic eruption. When the magma from, the volcanoes, get erupted they form different sized materials after solidification.
Ash is generally smaller than 2 mm in size, whereas Lapilli ranges from 2-64 mm in size.
4)True.
Stratovolcanoes are characterized by high viscosity,acidic lava that forms a explosive eruption.
5)True. If the lava coming out of the volcano is of low viscosity, then it flows over a large area and forms a layer of flood basalt.
6)False. Shield volcanoes get their name from their shield like structure, formed by the flow of low viscosity lava over a large area and with very low steepness.
7)True. As it is formed from the solidification of basaltic low viscosity lava, its surface gets rapidly cooled and forms the ropy appearance.
8)True.
9)False. a mass of molten volcanic material having a size greater than 64mm.
10)False. the types are: strato, shield and dome.
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