Ca Geology Ppt L#3

Front 1

1912 German meteorologist had an idea about continental movement. His hypothesis* was called ____. Ahead of his time.*

Back 1

Alfred Wegener*; Continental Drift*

Front 2

What was Wegener's evidence?

Back 2

1) Rocks/mountains are similar across the oceans.

2) Fossils: animals/plants found across continents.

3) Climate (paleoclimatologist how could this be possible?)

Front 3

Other scientists rejected Wegener's hypothesis because he couldn’t explain what was causing the continents to move (a.k.a. HOW?). No Mechanism.*
- He thought rotation of the Earth contributed to movement of continents but physicists said “no.”
- Also thought continents plowed through ocean floor but No evidence.

Back 3

NO MECHANISM (how?)*

Front 4

1929 geoscientist ___ speculated that ____ occurred in the mantle and could push and pull plates (continents) apart or together. Dense/cool ___ and hot/less dense ___. Stated that ____ contributed to heating. BUT NO EVIDENCE.*

Back 4

Arthur Holmes; convection*

sinking; rising;

radioactive decay*

Front 5

“A monster lays below” the oceans. The largest single feature on the planet and we never saw it before.*After years of mapping the sea floors we find a huge mountain range. Its volcanic, has a ridge down the center and is growing in width. The ___ system is PLANETARY IN SCALE.

Back 5

The Mid-Atlantic Ridge; Mid-Ocean Ridge system

Front 6

____in WWII (the 1940’s) began gathering data on the topography of the Pacific Ocean floor using ____. Not real accurate at first but he kept records and pursued the idea after the war.

Back 6

Harry Hess; sonar

Front 7

The ____ includes the the crust and a part of the mantle. Below this is the ___. Remember the radius of the earth (distance to the center) is about ____.

Back 7

Lithosphere; asthenosphere; 6,400 km or 4,000 miles

Front 8

The primary driving for all this (tectonic plates) is?

Back 8

convection

Front 9

Harry Hess used ___ and later ____ to support his ideas of convection as a source for continental drift. ___ came online in the 1950s.

Back 9

sea floor mapping; paleomagnetism; Age dating;

Front 10

_____ grains “floating” in hot lava tend to align with Earth’s magnetic field. Cooling at the _____ locks them into the alignment.This record provides information on the past behavior of Earth's magnetic field and the past location of tectonic plates.This is called ____ using volcanic rocks* (sometimes sedimentary). Oceanic rocks are volcanic too.*

Back 10

Magnetite;* Curie Point;* Paleomagnetism.*

Front 11

This device could detect small changes in the magnetic field in rocks and geologists can map them.

Back 11

Magnetometer

Front 12

The earth’s magnetic field switches polarity over geologic time. (At present time, rocks record a normal pattern because the north magnetic pole is in the northern hemisphere). Polarity patterns on both sides of the divergent zone are ____.

Back 12

the SAME

Front 13

A divergent margin is another name for the what?

Back 13

Spreading center

Front 14

Paleomagnetism + age dating = ?

-Technology to age-date rocks appeared in the 1950’s.

–Geologists originally thought ocean floors were as old or older than the continental rocks–NOT so!

The oceans (floors) are geologically ____ compared to the continents.***

Back 14

STRONG CORRELATION. young;

Front 15

Oceanic crust is very ___ compared to continental crust.*

Back 15

thin

Front 16

Polarity patterns on land matched to those at ___. Ages were the ___...nailed it!*

Back 16

sea; same

Front 17

Plate Tectonics –Modern Version developed & synthesized in the 1960’s by ____. For the first time in history we can begin to explain the predominant features on Earth and the processes that occur like Mountain ranges and oceans, Earthquakes and volcanis.

Back 17

Drummond Matthews, Fred Vine, Lawrence Morley (1963)*

Front 18

4 basic concepts to Plate tectonics Modern version.

Back 18

1) The lithosphere is made up of rigid units called plates

2)The plates move

3)Most of the world’s large-scale geological activity occurs AT or NEAR Plate Boundaries (volcanic eruptions/earthquakes)

4)The interiors of plates are relatively quiet geologically, with far fewer & milder earthquakes than occur at plate boundaries (BUT sometimes get a whopper in middle of plate. unusual though).

Front 19

Lithosphere is made up of _ major plates and numerous minor plates. What major ones touch North America? Plates are made up of oceanic and continental lithosphere. Which one is denser?

Back 19

7; North American Plate and the Pacific Plate (maybe South American plate too); Oceanic lithosphere is more denser (heavier).

Front 20

What are the boundaries between the plates? Describe them briefly.

Back 20

Convergent: where plates collide

Divergent: where plates move apart

Transform: plates move past one another in opposite directions (horizontal movement via Transform Faults)

Front 21

Similar Evidence to Support Plate Tectonics (or as it was called then, Continental Drift) but with new technology* we have some new* insight.

Back 21

-Fit” of the continents same as before: Africa and S. America.
-Distribution patterns same as before: of modern and ancient animals
-Distinctive rock types same as before: found at the margins of continents.
-Distribution of Paleozoic glaciations same as before.
-Polar reversals and wandering as evidenced by paleomagnetics–NEW TECHNOLOGY HELPS! ***

Front 22

Scientists saw potential alignment of continents & Alfred Wegener postulated moving continents & started the concept of “Continental Drift.” He was about 40 years ahead of most others. Couldn’t get support for the concept until new technology helped us discover:

Back 22

- Sea Floor Spreading: This was birth of Plate Tectonic Theory & the demise of Continental Drift.*
- Magnetic striping on ocean floor: new crust forms symmetrically along spreading ridges, & is documented by the magnetism “locked” into the minerals found in the crystallized magma at about the time of cooling. –Paleomagnetism became a science all of its own.
- Age dating of continental rocks and oceanic rocks

Front 23

The linking together of principles from different disciplines especially when forming a comprehensive theory.

Back 23

Consilience*

Front 24

The use of reasoning or arguments that sound correct but are actually false.

Back 24

sophistry*

Front 25

There is a map he showed us. It is a map of age dating. Red portions are YOUNG and HOT rocks and Mid Ocean Ridge

Back 25

?

Front 26

Today we can "watch" the plates move using ___.

Back 26

GPS

Front 27

The biggest mountain range on the planet is?

Back 27

under the ocean

Front 28

What's the Plate tectonics theory (the unifying theory of geological SYSTEM)good for?

Back 28

It helps explain how the earth works.

(Mountain building•Ocean basins getting larger & smaller•Earthquakes•Volcanism•Weathering•Faults•Even atmosphere)

Front 29

-spreading ridges
–rifts within continents
-extension sea floor spreading
what boundary?

Back 29

Divergent

Front 30

Places where there are spreading centers in land.

Back 30

Rift Valleys (Ex. East-Africa Rift valley)

Front 31

sometimes you see the map of a divergent boundary ridge being offset (bad alignment) because the process is not perfect. These offset alignments become _____.

Back 31

Transform faults

Front 32

_____ drives divergence.*

Back 32

Mantle convection

Front 33

-Collision zones: Continent-continent
–Subduction zones: Continent–ocean OR Ocean–ocean (trenches & volcanic arcs form here)

Back 33

convergent boundary

Front 34

In subduction, ____ is “dragged” down with the slab and acts as a ___ to partially melt subsurface rocks. This leads to high-silica magma that migrates upwards to fuel the _____. The slab/trench geometries tend to mirror the overlying volcanic arc geometries. They are related.

Back 34

water; catalyst volcanic arcs/chains

Front 35

This is a 2nd mechanism. Density of down-going slab acts as a heavy weight. Anchor-like. Will start dragging stuff with it.

Back 35

slab-pull

Front 36

When plates move past each other. horizontal.

Back 36

Transform

Front 37

San Andreas is a _____.

Back 37

transform fault

Front 38

When plates move around they add positive and negative stress with associated strain to the system. Something HAS to give and we see rock crushed, faulted, and folded. Three kinds?

Back 38

Lateral faults (left and right)

Normal faults

Reverse faults

Front 39

What type of fault is this? Overview movement.

Back 39

lateral fault. (right if it moves right and left if it moves left).

Front 40

Which one has compression and extension?

Back 40

Reverse fault has the hanging wall (makes a triangle right angle).

Reverse fault has compression (coming together/shortening)

Normal fault has extension (getting longer)

Front 41

If there is curve like in _____ (transform motion and extension together), a basin can form.

Back 41

transtension Ex. Fraizer Park (move away)

Front 42

If it squeezes together in ____ (transform motion and compresson), it makes mountains.

Back 42

transpression (move closer together)

Front 43

There are two types of folds.

Back 43

Anticline (have an A shape)

and Syncline (like a U shape)

Front 44

What type of fold is this?

Back 44

Anticline

Front 45

What type of fold is this?

Back 45

Syncline