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Revised: 07 / 22
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INDEX OF TOPICS
Astronomy and Space Science | Environment | Miscellaneous
The Physical Earth
What are the 4 states of matter? (6)
What are density and specific gravity? (7)
What is the best estimate of the densities of the various layers of the Earth? (57)
How have scientists discovered the density of the earth? (56)
Where on earth can the earth's crust be seen? (46)
What point on the Earth's surface is farthest from the center? (39)
Minerals
What do the terms mafic and felsic mean? (11)
Could you please tell me what "bulk rock chemistry" is? (80)
Why are oxygen and silica so important to the earth's crust? (24)
What is Bowen's Reaction Series? (32)
How does Bowen's Reaction Series relate to the classification of igneous rock? (48)
How does Bowen's Reaction Series affect chemical weathering? (91)
Name five common rock-forming minerals, and one characteristic feature of each. (30)
Why is feldspar important? (34)
Why is feldspar the most abundant mineral when quartz is the most common? (70)
How can I tell the difference between quartz and white feldspar in identifying rocks? (97)
Where can I get some really great quartz crystals? (2)
What is the softest crystal? (20)
Where do you find talc, the softest mineral in the world? (65)
Rocks
What do the terms mafic and felsic mean? (11)
Why do mafic magmas tend to reach the surface much more often than silicic magmas? (87)
Could you please tell me what "bulk rock chemistry" is? (80)
What are the 3 basic types of rocks? (13)
Why are basalt and granite the most important types of rock in the crust? (27)
Where is the most basalt? (78)
Why are granite and basalt more common than rhyolite and gabbro? (98)
Can you tell by looking at the soil whether the underlying bedrock is granite or basalt? (44)
How do composition and texture relate to igneous rocks? (14)
What is the difference between phaneritic and porphyritic textures? (95)
How come some dikes have smaller crystals on their edges? (37)
What percentage of the continental US is covered by ultramafic/mafic rocks? (23)
What is serpentinization? (45)
What igneous rock gives calcium to make limestone and marble? (25)
What is the difference between chalk and limestone? (50)
What can you add to water and expose to limestone to make it dissolve? (49)
How can I do the Fizz Test? (89)
Natural stone countertops: which rock would be the best? (47)
How would countertops made of schist compare to granite in terms of durability? (71)
Can you "polish" all rocks... or are there only certain rocks which will work? (55)
What sedimentary rocks are unlikely to form? What minerals are not "good" for forming? (68)
Internal Processes
What's in the center of the earth? (8)
What are density and specific gravity? (7)
What is the best estimate of the densities of the various layers of the Earth? (57)
How have scientists discovered the density of the earth? (56)
What is the deepest hole ever dug? (40)
What is the Brittle-Ductile Transition Zone? (10)
Global Tectonics
Click here for a summary of tectonic processes from the GeoTours section
Miscellaneous
What are cratons and greenstone belts? (12)
What is a continental basement? (31)
What's the difference between an active and passive continental margin? (26)
What processes lead to the formation of the major folded mountain belts? (58)
How does "dynamic equilibrium" relate to the earth's internal and external processes? (60)
What is the difference between a mountain range, a mountain system, and a mountain belt? (83)
Plate Tectonics
What are the characteristics of plate boundaries? (19)
Intraplate faulting and the New Madrid fault (81)
What causes the plates to move? (35)
Volcanology
I saw Dante's Peak last week. How accurate is it? (1)
What are pyroclastic flows? (33)
How can a volcano erupt mafic lava one time and then felsic lava another time? (88)
What are the effects of volcanic activity on the climate? (63)
Geologic Time and Earth History
How do geologists know how old things are? (17)
How do geologists determine the absolute ages of rocks with radioactive decay? (94)
How long has the earth been here? (16)
What is a stratigraphic column? (38)
How long has man been on earth? (42)
The Hydrosphere
When did the Missoula floods occur? (43)
Why does water always flow downstream? (90)
Why do objects float in water? (51)
What can you add to water and expose to limestone to make it dissolve? (49)
Why are global sea levels rising and why is it worrying? (61)
Why do rivers become wider and deeper downstream? (62)
Why is there a lag time between a storm and peak flow in a stream? (76)
Does building a dam affect erosion? (93)
Where does the water in a river come from if it's not raining? (77)
Why are most of the deserts and beaches sandy? And why are most of these sands quartz? (85)
Surface Processes
What are the main types and products of weathering? (59)
Why is exfoliation common in granite but not basalt? (73)
What is biological weathering? (92)
How does "dynamic equilibrium" relate to the earth's internal and external processes? (60)
Can you explain how waves can straigten an irregular coast line? (84)
How does Bowen's Reaction Series affect chemical weathering? (91)
Astronomy and Space Science
What is the difference between space and nothing? (21)
I am not exactly clear on the Nebular Hypothesis. Could you make some clarifications? (54)
The Environment
Why are global sea levels rising and why is it worrying? (61)
Why can't we put toxic waste into subduction zones? (79)
Miscellaneous
How does the scientific method work? (3)
What are the differences between regional and local views of the earth? (4)
What are the "laws" of geology? (5)
Are geologists sure that they're right about how the earth works? (15)
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You are visitor number since April 1, 1997