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HNRS 227 Lecture #18
Chapter 19
The Earth
presented by Prof. Geller
29 October 2002
Key Points of Chapter 19
Minerals
Rocks
Igneous, Sedimentary, Metamorphic
The Rock Cycle
Earth’s Interior
Crust, Mantle, Outer Core, Inner Core
Plate Tectonics
Telling Rocks Apart
How geologists tell apart different
minerals and rocks
color, luster, texture
hardness test
scratching one against another
• diamond is hardest
acid test
using weak hydrochloric acid to
streak test
form a streak across a ceramic tile
Minerals
(see Table 19.1)
Characteristics
naturally occurring
inorganic
definite crystalline structure
The natural resources of industry
Igneous Rocks
“Rocks formed from hot
molten mass of melted
rock material”
See Figure 19.11 in
textbook
Sedimentary Rocks
“Rocks formed from
particles or dissolved
materials from previously
existing rocks.”
See Table 19.2 in textbook
Metamorphic Rocks
“Previously existing rocks that
have been changed by heat,
pressure, or hot solutions into
a distinctly different rock.”
See Figure 19.13 in textbook
The Rock Cycle
Earth’s Interior and
How We Know It
Earthquakes Galore
Earth’s Inside Story
Crustal Rumblings
Plate Tectonics
“The theory that the Earth’s crust is made
of rigid plates that float on the
asthenosphere.”
Consider the scientific evidence for plate
tectonics and what forced scientists to
accept the theory as fact
Fossils across an ocean
Boundaries Galore
Plates are smashing