Physical Geology - CH 1-4

Physical geology chapters 1-4 test review

Define Geology

The scientific study of earth

3 practical applications of geology

Natural resources, resource extraction/environmental protection, avoiding geologic hazards

absolute geologic time

puts an absolute age to rocks/minerals

relative geologic age

gives an age of one geologic event relative to another

history of life

fossils

define minerals

naturally occuring, inorganic, crystalline structure, solid, specific chemical composition

polymorphs

minerals with the same chemical composition but different crystalline structure

mohs hardness scale

1. talc

2. gypsum

3. calcite

4. fluorite

5. apatite

6. felspar

7. quartz

8. topaz

9. corundum

10. diamond

11. fingernail 2.5

12. copper penny 3.5

13. glass plate 5.5

define rock

an aggregate of consolidated grains of one or more minerals or mineral-like substances

mafic

Mg and Fe rich magma

felsic

silica and potassium rich magma

intermediate

combo of mafic and felsic

ultramafic

primarily mafic

bowen’s reaction series

minerals crystalize in a predictable order over a large temperature range

discontinuous

ferromagnesian minerals crystalize in sequence with decreasing temperatures

discontinuous minerals list

1. olivine

2. pyroxene

3. amphibole

4. biotite

continuous

plagioclase feldspar forms with a chemical composition that evolves (from Ca-rich to Na-rich) with decreasing temperatures

How does magma form

minerals in a rock must melt. each mineral must reach their unique melting point. partial melting rocks melt over a range of temperatures

Assimilation occurs when…

a hot magma melts and incorporates more felsic surrounding rocks

magma mixing involves…

the mixing of more of less mafic magmas to produce one of intermediate composition

intrusive magma bodies

form in warm country rock (course grained)

diapirs

large blobs of magma that work their way through less dense rock

plutons

body of magma that crystallizes at great depths below earth’s surface

batholiths

collection of plutons

different types of volcanoes

1. shield volcanoes

2. cinder cones

3. composite volcanoes

4. volcanic domes

5. calderas

6. craters

7. flood eruptions

factors that contribute to more violent eruptions

magma viscosity, amount of dissolved gas, ease that the gases can escape

volcanic rock texture

controlled by cooling rate

importance of scientific investigation of volcanoes

rocks, gases, and events from observed eruptions compared to similar lava events elsewhere to infer the nature of the past activity.

very useful in geologic age dating of rock layers