Questions related to igneous rocks and volcanoes: The Dynamic Earth

1. In general, is the material in magma entirely in the liquid state?
2. What is magma?
3. What do igneous rocks form from?
4. Does magma originate in a liquid layer that exists below the crust worldwide?
5. Within what layer(s) of Earth's interior are magmas typically generated?
6. What is a representative average temperature for basaltic magmas?
7. How is the viscosity of basaltic magmas generally described?
8. What is a representative average temperature for silicic magmas?
9. How is the viscosity of silicic magmas generally described?
10. What causes magmas to rise from the area below Earth's surface where they were generated?
11. Igneous rock is divided into two broad categories based on whether it forms below Earth's surface or near/at Earth's surface. What is the name of the category of igneous rock that forms near/at Earth's surface?
12. What is the name of the category of igneous rock that forms below Earth's surface?
13. What characteristic of a fluid is described by its viscosity?
14. Do mafic magmas generally have more or less silica than silicic magmas?
15. Are mafic magmas generally hotter or cooler than silicic magmas?
16. Are mafic magmas generally more viscous or less viscous than silicic magmas?
17. Given two magmas extruded onto Earth's surface. Which would be more likely to flow rapidly: a mafic magma or a silicic magma?
18. What are two of the most abundant gases emitted by typical volcanic eruption?
19. What effect does dissolved water tend to have on the viscosity of a magma?
20. What effect does gas (specifically, gas bubbles) tend to have on the viscosity of a magma?
21. In what tectonic environment do most igneous rock bodies form within/on oceanic crust?
22. What feature in the mantle is most commonly associated with active volcanism that occurs in the interior of plates, away from active plate boundaries?
23. What is the descriptive term related to the size, shape and arrangement of minerals in a rock?
24. When an igneous rock is composed of grains whose size is small (<~1 mm) and generally similar throughout the rock, how do we describe its texture?
25. When an igneous rock is composed of grains whose size is medium to large (>1 mm) and generally similar throughout the rock, how do we describe its texture?
26. When an igneous rock has a grain-size distribution that is bimodal (i.e., contains larger grains embedded in smaller grains), how do we describe its texture?
27. What is the general interpretation of the cooling rate of an igneous material based on a glassy texture?
28. What is the general interpretation of the cooling rate of an igneous rock based on an aphanitic texture?
29. What is the general interpretation of the cooling rate of an igneous rock based on an phaneritic texture?
30. What is the general interpretation of the cooling rate of an igneous rock based on an porphyritic texture?
31. What is the fine-grained material in a porphyritic rock called?
32. What are the coarse-grained crystals in a porphyritic rock called?
33. Are aphanitic igneous rocks generally intrusive or extrusive?
34. Are phaneritic igneous rocks generally intrusive or extrusive?
35. Are glassy igneous materials generally intrusive or extrusive?
36. What is the origin of a pyroclastic texture?
37. Name the rock type: a light-toned igneous rock with a coarse grain size, potassium and plagioclase feldspar, a significant amount of quartz, and some dark minerals.
38. Name the rock type: an intermediate-toned igneous rock with a coarse grain size, plagioclase and maybe some potassium feldspar, maybe some quartz, and up to ~40% dark minerals.
39. Name the rock type: a dark-toned igneous rock with a coarse grain size, plagioclase feldspar, no quartz, and ~40-90% dark minerals (mostly olivine and pyroxene).
40. Name the rock type: a dark-toned igneous rock with a coarse grain size, perhaps some plagioclase feldspar, and at least 90% dark minerals (olivine, pyroxene).
41. Name the rock type: a light-toned igneous rock with a fine grain size, potassium and plagioclase feldspar, a significant amount of quartz, and some dark minerals.
42. Name the rock type: an intermediate-toned igneous rock with a fine grain size, plagioclase and maybe some potassium feldspar, maybe some quartz, and up to ~40% dark minerals.
43. Name the rock type: a dark-toned igneous rock with a fine grain size, plagioclase feldspar, no quartz, and ~40-90% dark minerals (mostly olivine and pyroxene).
44. What kind of rock represents the average composition of the continental crust?
45. What kind of rock represents the average composition of the oceanic crust?
46. What kind of volcanic flow is composed of a jumbled mass of angular blocks -- a Hawaiian word.
47. What kind of volcanic flow produces twisted, ropey structures -- a Hawaiian word.
48. What kind of very regular joints are produced by the contraction and cracking of an igneous flow, commonly resulting in multi-sided columns of igneous rock?
49. What is the term associated with all pyroclastic material ejected from a volcano?
50. What is the name of a rock formed by the accumulation of pyroclastic fragments, often in layers?
51. What is a volcanic bomb?
52. What do we call an igneous material made of a glassy froth or bubble structure, that floats in water until it is saturated?
53. What is the most common type of volcanic eruption on Earth?
54. What type of volcano has a very broad base and very gently sloping sides?
55. What type of volcano has a relatively narrow base and sides that slope steeply at >~30Á?
56. What kind of magma (mafic or silicic) is associated with explosive eruptions?
57. What kind of magma (mafic or silicic) is associated with shield volcanoes?
58. What kind of magma (mafic or silicic) is associated with composite or strata-volcanoes?
59. What kind of magma (mafic or silicic) is associated with the partial melting of the upper mantle?
60. What kind of magma (mafic or silicic) is associated with the partial melting of material in the continental crust, perhaps mixed with other constituents?
61. What kind of volcano is built up of alternating layers of ash and lava flows, and is intruded by lava domes?
62. What is the name given to an intrusive igneous body with a surface exposure of less than 100 square kilometers?
63. What is the name given to an intrusive igneous body with a surface exposure of more than 100 square kilometers?
64. What is the name given to a tabular intrusive igneous body that cuts across pre-existing layering in the rock that it intrudes?
65. What is the name given to a tabular intrusive igneous body that is parallel to pre-existing layering in the rock that it intrudes?
66. What is the name given to the core of an extinct volcano, exposed after the flanks of the volcano have been eroded?
67. Why is there such great variability in the composition of magma?
68. What is the process whereby the composition of the liquid magma evolves to become more silicic because mafic minerals crystallize from the melt first, at higher temperature?
69. When the upper mantle is partially melted, and that melt crystallizes, what kind of igneous rock results from that crystallization?

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