· 8 years ago · Dec 02, 2017, 03:50 AM
1Asthenosphere:
2A subdivision of the mantle situated below the lithosphere. This zone of weak material exists below a depth of about 100 kilometers and in some regions extends as deep as 700 kilometers. The rock within this zone is easily deformed.
3
4Atmosphere:
5The gaseous portion of a planet, the planet’s envelope of air. One of the traditional subdivisions of Earth’s physical environment.
6
7Biosphere:
8 The totality of life forms on Earth.
9
10Catastrophism:
11 The concept that Earth was shaped by catastrophic events of a short-term nature.
12
13Core:
14The innermost layer of Earth based on composition. It is thought to be largely an iron-nickel alloy with minor amounts of oxygen, silicon, and sulfur.
15
16Crust:
17 The very thin outermost layer of Earth.
18
19Hypothesis:
20 A tentative explanation that is then tested to determine if it is valid.
21
22Igneous rock:
23 Rock formed from the crystallization of magma.
24
25Inner core:
26 The solid innermost layer of Earth, about 1216 kilometers in radius.
27
28Lithosphere:
29 The rigid outer layer of Earth, including the crust and upper mantle.
30
31Mantle:
32One of Earth’s compositional layers. The solid rocky shell that extends from the base of the crust to a depth of 2900 kilometers.
33
34Metamorphic rock:
35Rock formed by the alteration of preexisting rock deep within Earth by heat, pressure, and/or chemically active fluids.
36
37Oceanic (mid-ocean) ridge:
38A continuous mountainous ridge on the floor of all the major ocean basins and varying in width from 500 to 5000 kilometers. The rifts at the crests of these ridges represent divergent plate boundaries.
39
40
41Outer core:
42 A layer beneath the mantle about 2270 kilometers thick, which has the properties of a liquid.
43
44Rock cycle:
45A model that illustrates the origin of the three basic rock types and the interrelatedness of Earth materials and processes.
46
47Sedimentary rock:
48Rock formed from the weathered products of preexisting rocks that have been transported, deposited, and lithified.
49Theory:
50 A well-tested and widely accepted view that explains certain observable facts.
51
52Uniformitarianism:
53The concept that the process that have shaped Earth in the geologic past are essentially the same as those operating today.
54
55Review questions:
56
57#1) Geology is traditionally divided into two broad areas. Name and describe these two subdivisions.
58Physical geology examines the materials that make up the Earth and attempts to understand the numerous ongoing processes beneath the Earth and on its surface. Historical geology is meant to understand how the Earth originated and how it developed through time.
59
60#6) The geologic time scale was established without the aid of radiometric dating. What principles were used to develop the time scale?
61A geologic time scale was developed using principles of relative dating. Relative dating is a process in which events are placed in their proper sequence or order without knowing their exact age in years. This is done by using other principles such as the law of superposition (with materials such as layers of sedimentary rock and volcanic lava flows, the youngest layer is on top and the oldest layer is on the bottom). Fossils and the principle of fossil succession (fossil organisms success one another in a definite and indeterminable order, and therefore any time period can be recognized by its fossil content) were also used to establish a geologic time scale.
62
63Chapter 2
64Define the following words:
65
66Continental drift:
67A hypothesis, credited largely to Alfred Wegener, that suggested all present continents once existed as a single supercontinent. Further, beginning about 200 million years ago, the supercontinent began breaking into smaller continents, which then “drifted†to their present positions.
68
69Lithospheric plate:
70 A coherent unit of Earth’s rigid outer layer that includes the crust and upper unit.
71
72Plate tectonics:
73The theory that proposes that Earth’s outer shell consists of individual plates that interact in various ways and thereby produce earthquakes, volcanoes, mountains, and the crust itself.
74
75Ridge push:
76A mechanism that may contribute to plate motion. It involves the oceanic lithosphere sliding down the oceanic ridge under the pull of gravity.
77
78
79
80Seafloor spreading:
81The hypothesis, first proposed in the 1960s by Harry Hess, which suggested that new oceanic crust is produced at the crests of mid-ocean ridges, which are the sites of divergence.
82
83Slab-pull:
84A mechanism that contributes to plate motion in which cool, dense oceanic crust sinks into the mantle and “pulls†the trailing lithosphere along.
85
86Spreading center:
87A boundary in which two plates move apart, resulting in upwelling of material from the mantle to create new seafloor.
88
89Subduction zone:
90 A long, narrow zone where one lithosphere plate descends beneath another.
91
92Review question:
93
9412) List the three types of plate boundaries and describe the relative motion at each of them.
95Divergent plate boundaries:
96Two plates move apart, resulting in upwelling of hot material from the mantle to create new seafloor.
97Convergent plate boundaries:
98Two plates move together, resulting in oceanic lithosphere descending beneath an overriding plate, eventually to be reabsorbed into the mantle, or possibly in the collision of two continental blocks to create a mountain system.
99Transform fault boundaries:
100Two plates grind past each other without the production or destruction of the lithosphere.
101
102GLY1010 - Intro Earth Science / MWF 10:00-10:50am / RB
103 Week of 08/22/11 - 08/26/11
104The Science of Geology
105 Geology:
106 The science that pursues an understanding of planet Earth.
107 Physical:
108 Examines Earth materials and seeks to understand the many processes that operate on our planet.
109 Historical:
110 Seeks an understanding of the origin of Earth and its development through time.
111 Relative dating:
112 Dates are placed in their proper sequence or order without knowing their specific age.
113 Super position:
114 In a sequence of sedimentary rock or lava flows, the youngest layer is on top and the oldest layer is on the bottom.
115 Principle of fossil succession:
116 Fossil organisms succeed one another in a dfinite and determinable order. Therefore, any time period can be recognized by its fossil content.
117 Earth's four spheres:
118 Hydrosphere:
119 Atmosphere:
120 Biosphere:
121 Geosphere:
122 System:
123 Any size group of interacting parts that form a complex whole.
124 Feedback machanisms:
125 Negative:
126 Maintains the status quo.
127 Positive:
128 Enhances or drives changes.
129 Cycles in the Earth:
130 Hydrologic cycle:
131 Rock cycle:
132 Interface:
133 Common boundary where different parts of a system come in contact and interact.
134 08/30/11
135Early Evolution of Earth pg. 19
136 Formation of Earth's layered structure
137 Metals sank to the center.
138 Molten rock rose to produce a primitive crust.
139 Chemical segregation established the three basic divisions of Earth's interior.
140 A primitive atmosphere evolved from gases in Earth's interior.
141Earth's Internal Structure pg. 23
142 Layeres defined by composition:
143 Crust
144 Mantle
145 Core
146 Layers defined by physical properties:
147 Lithosphere
148 Asthenosphere
149 Mesosphere
150 Inner and outer core
151The Face of Earth pg. 25
152 Earth's surface:
153 Continents
154 Oceans
155 Continents:
156 Mountain belts
157 The most prominent feature of continents
158 The stable interior
159 Also called a craton
160 Composed of shields and stable platforms
161 Ocean basins:
162 Contintental margins
163 Includes the continental shelf, continental slope, and the continental rise.
164 Deep-ocean basins
165 Abyssal plains
166 Oceanic trenches
167 Seamounts
168 Ocean Ridge System
169 Most prominent topographic feature on Earth
170 Composed of igneous rock that has been fractured and uplifted
171Rocks and the Rock Cycle pg. 29
172 Basic rock types:
173 Igneous rocks
174 Cooling and solidification of magma
175 Examples: granite and basalt
176 Sedimentary rocks
177 Accumulate in layers at Earth's surface
178 Sediments are derived from weathering of preexisting rocks
179 Examples: sandstone, limestone
180 Metamorphic rocks
181 Formed by "changing" preexisting igneous, sedimentary, or other metamorphic rocks
182 Driving forces: heat and pressure
183 Examples: gneiss and marble
184 The rock cycle: One of Earth's Subsystems
185 The loop that involves the processes by which one rock changes to another
186 Illustrates the various processes and paths as Earth materials change both on the surface and inside the Earth
187 CHAPTER 2
188Continental drift: An Idea Before Its Time
189 Alfred Wegener
190 First proposed continental drift hypothesis in 1915
191 Published The Origin of Continents and Oceans
192 Continental drift hypothesis
193 The supercontinent called Pangaea began breaking apart about 200 million years ago
194 Continents "drifted" to present positions
195 Evidence used in support of continental drift hypothesis
196 Fit of the continents
197 Fossil evidence
198 Rock type and structural similarities
199 Paleoclimatic evidence
200The Great Debate pg. 45
201 Objections to the continental drift hypothesis
202 Lack of a mechanism for moving continents
203 Wegener incorrectly suggested that continents broke through the ocean crust
204 Strong oppposition to the hypothesis from all areas of the scientific community
205 Continental drift and the Scientific Method
206 Wegener's hypothesis was correct in principle, but contained incorrect details.
207 A few scientists considered Wegener's ideas plausible and continued the search
208 Continental drift and Paleomagnetism
209 A renewed interest in continental drift initially came from rock magnetism
210 Magnetized minerals in rocks:
211 Show the direction to Earth's magnetic poles
212 Provide a means of determining their latitude of origin
213 Polar Wandering
214 The apparent movement of the magnetic poles indicates that the continents have moved
215 It also indicates Europe was much closer to the equator when coal-producing swamps existed
216A Scientific Revolution Begins pg. 48
217 During the 1950s and 1960s, technological strides permitted extensive mapping of the ocean floor
218 The seafloor spreading hypothesis was proposed by Harry Hess in the early 1960s
219 Geomagnetic reversals:
220 Earth's magnetic field periodically reverses polarity - the north pole becomes the south pole, and vice versa
221 Dates when the polarity of Earth's magnetism changed were determined from lava flows
222 Geomagnetic reversals are recorded in the oceanic crust
223 In 1963, Vine and Matthews tied the discovery of magnetic stripes in the oceanic crust near ridges to Hess's concept of seafloor spreading
224 08/31/11
225Plate Tectonics: The New Paradigm pg. 51
226 Earth's major plates
227 Associated with Earth's strong, rigid outer layer:
228 Known as the lithosphere
229 Consists of uppermost mantle and overlying crust
230 Overlies a weaker region in the mantle called the asthenosphere
231 Seven major lithospheric plates
232 Plates are in motion and are continually changing in shape and size.
233 The largest plate is the Pacific plate.
234 Several plates include an entire continent plus a large area of seafloor.
235 Plates move relative to each other at a very slow but continuous rate.
236 About 5 centimeters (2 inches) per year
237 Cooler, denser slabs of oceanic lithosphere descend into the mantle.
238 Plate boundaries pg. 54
239 Interactions among individual plates occur along their boundaries.
240 Types of plate boundaries:
241 -Divergent plate boundaries (constructive margins)
242 Most are located along the crests of oceanic ridges.
243 Oceanic ridges and seafloor spreading
244 Along well-developed divergent plate boundaries, the seafloor is elevated, forming oceanic ridges.
245 Seafloor spreading occurs along the oceanic ridge system.
246 Spreading rates and ridge topographic
247 Ridge systems exhibit topographic differences.
248 Differences are controlled by spreading rates.
249 Continental rifting
250 Splits landmasses into two or more smaller segments along a continental rift
251 Examples include:
252 East African Rift Vallets
253 Rhine Valley in Northern Europe
254 Produced by extensional forces
255 -Convergent plate boundaries (destructive margins) pg. 56
256 Older portions of oceanic plates are returned to the mantle at these destructive plate margins.
257 Surface expression of the descending plate is an ocean trench.
258 Also called subduction zones
259 Average angle of subduction = 45 degrees.
260 Types of convergent boundaries:
261 Oceanic-continental convergence
262 The denser oceanic slab sinks into the asthenosphere.
263 Along the descending plate, partial melting of mantle rock generates magma.
264 The resulting volcanic mountain chain is called a continental volcanic arc. (The andes and the Cascades are examples.)
265 Oceanic-oceanic conergence
266 When two oceanic slabs converge, one descends heneath the other.
267 Often forms volcanoes on the ocean floor
268 If the volcanoes emerge as islands, a volcanic island arc is formed. (japan, the Aleuntian islands, and the Tonga islands are examples.)
269 pg. 58
270 Continental-continental convergence
271 Continued subduction can bring two continents together.
272 Less dense, buoyant continental lithospherer does not subduct.
273 The resulting collision produces mountains (The Himalayas, the Alps, and the Appalachians are examples.)
274 pg 59.
275 Nice figure pg. 223
276 -Transform Fault Boundaries (conservative margins)
277 Plates slide past one another and no new lithosphere is created or destroyed.
278 Transform faults
279 Most join two segmentss of a mid-ocean ridge along breaks in the oceanic crust known as fracture zones.
280 A few (the San Andreas Fault and the Alpine Fault of New Zealand) cut through continental crust.
281 09/02/11
282Testing the Plate Tectonics Model pg. 64
283 Hot spots and mantle plumes
284 Caused by rising plumes of mantle material
285 Volcanoes can form over them (Hawaiian Island chain).
286 Mantle plumes
287 Long-lived structures
288 Some originate at great depth.
289 What Drives Plate Motions?
290 Researchers agree that convective flow in the mantle is the basic driving force of plate tectonics.
291 Forces that drive plate motion:
292 Slab-pull
293 Ridge push pg. 67
294 Models of plate-mantle convection
295 Any model must be consistent with observed physical and chemical properties of the mantle.
296 Models:
297 Layering at 660 kilometers
298 Whole-mantle convection
299Importance of Plate Tectonics
300 The theory provides explanations for:
301 Earth's major surface processes
302 Distribution of earthquakes, volcanoes, and mountains
303 Distribution of ancient organisms and mineral deposits
304=============================END OF CHAPTER 2==================================
305 09/07/11
306 CHAPTER 3 PG 74
307Minerals: Building Blocks of Rocks
308 By definition a mineral is:
309 Naturally occurring
310 An inorganic solid
311 Ordered internal molecular structure
312 Definite chemical composition
313 Rock
314 A solid aggregate of minerals
315 pg 76
316Composition of Minerals
317 Chemical bonding
318 Formation of a compound by combining two or more elements
319 Ionic bonding
320 Atoms gain or lose outermost (valence) electrons to form ions.
321 Ionic compounds consist of an orderly arrangement of oppositely charged ions.
322 Covalent bonding
323 Atoms share electrons to achieve electrical neutrality.
324 Generally stronger than ionic bonds
325 Both ionic and covalent bonds typically occue in the same compound.
326Structure of Minerals
327 Minerals consist of an orderly array of atoms chemically bonded to form a particular crystalline structure.
328 The internal atomic arrangement in ionic compounds is determined by ionic size.
329 pg 87
330Physical Properties of Minerals
331 Primary diagnostic properties
332 Determined by observation or performing a simple test
333 Several physical properties are used to identify hand samples of minerals.
334 Crystal form
335 External expression of a mineral's internal structure
336 Luster
337 Appearance of a mineral in reflected light
338 Two basic categories:
339 1. Metallic
340 2. Nonmetallic
341 Color
342 Generally unreliable for mineral identification
343 Streak
344 Color of a mineral in its powdered form
345 Hardness
346 Resistance of a mineral to abrasion or scratching
347 All minerals are compared to a standard scale called the Mohs scale of hardness.
348 pg 89
349 Cleavage
350 Tendency to break along planes of weak bonding
351 Produces flat, shiny surfaces
352 Described by resulting geometric shapes
353 Number of planes
354 Angles between adjacent planes
355 Fracture
356 Absence of cleavage when a mineral is broken
357 Specific gravity
358 Weight of a mineral / weight of an equal volume of water
359 Average value = 2.7
360 pg 92
361 Other properties:
362 Magnetism
363 Reaction to hydrochloric acid
364 Malleability
365 Double refraction
366 Taste
367 Smell
368 Elasticity
369 pg 93
370Mineral Groups
371 Nearly 4000 minerals have been named
372 Rock-forming minerals
373 Common minerals that make up most of the rocks of Earth's crust
374 Only a few dozen members
375 Compoased mainly of the eight elements that make up more than 98% of the continental crust.
376 Silicates
377 Most important mineral group
378 Comprise most rock-forming minerals
379 Very abundant due to large percentage of silicon and oxygen in Earth's crust
380 Silicon-oxygen tetrahedron
381 Fundamental building block
382 Four oxygen ions surrounding a much smaller silicon ion
383 09/09/11
384 Joining silicate structures
385 Single tetrahedra are linked together to form various structures including:
386 Isolated tetrahedra
387 Ring structures
388 Single and double-chain structures
389 Sheet or layered structures
390 Complex three-dimensional structures
391 pg 94 fig.
392 Common silicate minerals
393 Light silicates: feldspar group
394 Most common mineral group
395 Exhibit two directions of perfect cleavage at 90 degrees
396 Orthoclase (potassium feldspar) and plagioclase (sodium and calcium feldspar) are the two most common members.
397 Light silicates: quartz
398 Only common silicate composed entirely of oxygen and silicon
399 Hard and resistant to weathering
400 Conchoidal fracture
401 Often forms hexagonal crystals
402 Light silicates: muscovite
403 Common member of the mica family
404 Excellent cleavage in one direction
405 Produces the "glimmering" brilliance often seen in beach sand
406 Light silicates: clay minerals
407 Clay is a general term used to describe a variety of complex minerals/
408 Exhibit a sheet or layered structure
409 Most originate as products of chemical weathering.
410 Dark silicates: olivine group
411 High temperature Fe-Mg silicates
412 Individual tetrahedra are linked together by Fe and Mg ions.
413 Forms small, rounded crystals with no cleavage
414 Dark silicates: pyroxene group
415 Single-chain structures involving iron and magnesium
416 Two distinctive cleavages at nearly 90 degrees
417 Augite is the most common mineral in the pyroxene group.
418 Dark silicates: amphibole group
419 Double-chain structures involving a variety of ions
420 Two perfect cleavages exhibiting angles of 124 and 56 degrees
421 Hornblende is the most common mineral in the amphibole group.
422 pg 99
423 Important nonsilicate minerals
424 Typically divided into classes based on anions
425 Comprise only 8% of Earth's crust
426 Often occur as constituents in sedimentary rocks
427 Carbonates
428 Primary constituents in limestone and dolostone
429 Calcite (CaCO_3) and dolomite CaMg(CO_3)_2 are the two most important carbonate minerals.
430 Many nonsilicate minerals have economic value.
431 Examples:
432 Hematite (oxide mined for iron ore)
433 Halite (halide mined for salt)
434 Sphalerite (sulfide mined for zinc ore)
435 Native copper (native element mined for copper)
436========================END OF CHAPTER 3============================
437 09/12/11
438========================CHAPTER 4==================================
439General Characteristics of Magma
440 Igneous rocks form as molten rock cools and solidifies.
441 General characteristics of magma:
442 Parent material of igneous rocks
443 Forms from partial melting of rocks
444 Magma at surface is called lava.
445 Rocks formed from lava are extrusive, or volcanic rocks.
446 Rocks formed from magma at depth are intrusive, or plutonic rocks.
447 The nature of magma
448 Consists of three components:
449 1. Liquid portion = melt
450 2. Solids, if any, are silicate minerals.
451 3. Volatiles are dissolved gases in the melt, including water vapor (H20), carbon dioxide (CO2), and sulfur dioxide (SO2).
452 Crystallization of magma
453 Cooling of magma results in the systematic arrangement of ions into orderly patterns.
454 Silicate minerals result from crystallization in a predictable order.
455 Texture is the size and arrangement of mineral grains.
456 pg 108, 109, 110
457Ignerous Textures
458 Texture is the overall appearance of a rock based on the size, shape, and arrangement of interlocking minerals.
459 Factors affecting crystal size:
460 Rate of cooling
461 Slow rate = fewer but larger crystals
462 Fast rate = many small crystals
463 Very fast rate forms glass.
464 Factors affecting crystal size:
465 Percentage of silica (SiO2) present
466 Dissolved gases
467 Types of igneous textures
468 Aphanitic (fine-grained) texture
469 Rapid rate of cooling
470 Microscopic crystals
471 May contain vesicles (holes from gas bubbles)
472 Phaneritic (coarse-grained) texture
473 Slow cooling
474 Large, visible crystals
475 Porphyritic texture
476 Minerals form at different temperatures.
477 Large crystals (phenocrysts) are embedded in a matrix of smaller crystals (groundmass).
478 Glassy texture
479 Very rapid cooling of lava
480 Rock is called obsidian.
481 pg 110
482Igneous Compositions
483 Granitic versus basaltic compositions
484 Granitic composition
485 Light-colored silicates
486 Termed felsic (felspar and silica) in composition)
487 High silica (SiO2) content
488 Major consituent of continental crust
489 Basaltic composition
490 Dark silicates and calcium-rich feldspar
491 Termed mafic (magnesium and ferrum, for iron) in composition
492 High density than granitic rocks
493 Comprise the ocean floor and many volcanic islands
494 Other compositional groups
495 Intermediate (or andesitic) composition
496 Contain 25% or more dark silicate minerals
497 Associated with explosive volcanic activity
498 Ultramafic composition
499 Rare composition that is high in magnesium and iron
500 Composed entirely of ferromagnesian silicates
501 pg 111 fig 4.24
502 Silica content as an indicator of composition
503 Crustal rocks exhibit a considerable range--- 45% to 70%
504 Silica content influences magma behavior.
505 Granitic megmas have high silica content and are viscous.
506 Basaltic magmas have much lower silica content and more fluid-like behavior.
507 09/14/11
508TEST 1 ON FRIDAY, CHAPTERS 1, 2, 3, PART OF 4
509 Naming igneous rocks---granitic rocks
510 Granite
511 Phaneritic
512 Over 25% quartz, about 65% or more feldspar
513 Very abundant---often associated with mountain building
514 The term granite includes a wide range of mineral compositions.
515 Rhylite
516 Extrusive equivalent of granite
517 May contain glass fragments and vsicles
518 Aphanitic texture
519 Less common and less voluminous than granite
520 Obsidian
521 Dark colored
522 Gladdy texture
523 Pumice
524 Volcanic
525 Glassy texture
526 Frothy appearance with numerous voids
527 Andesite
528 Volcanic origin
529 Aphanitic texture
530 Diorite
531 Plutonic equivalent of andesite
532 Coarse-grained
533 pg 119
534 Naming igneous rocks---basaltic rocks
535 Basalt
536 Volcanic origin
537 Aphanitic texture
538 Composed mainly of pyroxene and calcium-rich plagioclase feldspar
539 Most common extrusive igneous rock
540 Naming igneous rocks---mafic rocks
541 Gabbro
542 Intrusive equivalent of basalt
543 Phaneritic texture consisting of pyroxene and calcium-rich plagioclase
544 Significant percentage of the oceanic crust
545 pg 115 table
546 EXAM CUTOFF pg 120
547According to the principle of uniformitarianism, ___
548 A. geologic processes we observe today have operated similarly in the past
549
550The currently accepted age of the Earth is _____ years
551 C. 4.6 billion
552
553All silicate minerals contain the elements _______
554 D. silicon and oxygen
555
556Which one of the following statements is not corrent?
557 B. Sedimentary rocks may weather to igneous rocks.