1. Vagabonds Tramping through Geology: Austin to the Arctic
WINTER 2012
Vagabonds Tramping through Geology: Austin to the Arctic

2. GEOLOGY & TRAVEL

3. GEOLOGY & TRAVEL What’s the linkage??
Proposition: GEOLOGY is the main reason for most travel destinations
Mountain biking/hiking, downhill skiing, breath-taking vistas,
Ski resorts, river cruises, tour dams
Water skiing on lakes/ponds,
Ocean cruises, island hoping,
Waterfalls, gorges
MOUNTAINS
VALLEYS
GLACIERS, EROSION, VALLEYS
TECTONIC PLATE MOVEMENT, VOLCANOS
FAULTING, EROSION

4. Proposition: GEOLOGY is the main reason for most travel destinations
GEOLOGY & TRAVEL
What’s the linkage??
Proposition: GEOLOGY is the main reason for most travel destinations
Local soils…local ecology…local plant/ animal life…
different hunting/fishing environments,
different type crops & vineyards,
different grasses grown…different type herds raised…milk/cheese manuf.

5. So, let’s get Crack-a-lacking!
CLASS OBJECTIVES
Understand the Geologic Processes that shape our planet
Understand past Geologic Events that formed our continent
Understand the Geology of the Pacific Northwest
Understand the linkages between Geology & Travel in your own travels
Share our passion for Geology & Travel and pass that on to your kids/grandkids/great-grandkids
So, let’s get Crack-a-lacking!

6. EARTH
HOW BIG IS IT?
WHAT IS IT MADE OF?
HOW & WHY DO PLATES MOVE?

7. HOW BIG IS EARTH? 7,940 mi (24,901 mi in circumference)
(in 80 days = 13mph)

8. What is EARTH made of? Crust Upper Mantle (solid) (partially molten)
25 mi
Upper Mantle
(partially molten)
415 mi
Lower Mantle
(solid)
1385 mi
EARTH'S MAKEUP
Thickness
Crust, solid 25 mi
Upper Mantle (Partially molten)
400
Lower Mantle, solid
1385
Outer Core, Liquid
1400
Inner Core, Liquid
760
Total Thickness
3970 x 2
Total Diameter
7940
Outer Core
(liquid)
1400 mi
Inner Core
(solid)
760 mi
What is EARTH made of?

9. National Geographic, Jan 1996

10. Two Types of Crust
Continental Crust: under the continents;
From 20 to 50 miles thick
continental lithosphere consists mainly of felsic crust and is lighter than the oceanic lithosphere
Oceanic Crust: under the oceans; About 5 miles thick
Oceanic lithosphere consists mainly of mafic crust and ultramafic mantle (peridotite) and is denser than continental lithosphere
Mafic is an adjective describing a silicate mineral or rock that is rich in magnesium and iron; the term is a portmanteau of the words "magnesium" and "ferric".[1] Most mafic minerals are dark in color and the relative density is greater than 3. Common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks include basalt, dolerite and gabbro.
In terms of chemistry, mafic rocks are on the other side of the rock spectrum from the felsic rocks. The term roughly corresponds to the older basic rock class.
Mafic lava, before cooling, has a low viscosity, in comparison to felsic lava, due to the lower silica content in mafic magma. Water and other volatiles can more easily and gradually escape from mafic lava, so eruptions of volcanoes made of mafic lavas are less explosively violent than felsic-lava eruptions. Most mafic-lava volcanoes are oceanic volcanoes, like those in Hawaii.
The word "felsic" is a term used in geology to refer to silicate minerals, magma, and rocks which are enriched in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium.
They are usually light in color and have specific gravities less than 3. The most common felsic rock is granite, but others include quartz, muscovite, orthoclase, and the sodium-rich plagioclase feldspars. In terms of chemistry, felsic rocks are on the other side of the rock spectrum from the mafic rocks.
In order for a rock to be classified as felsic, it generally needs to contain >75% felsic minerals; namely quartz, orthoclase and plagioclase. Rocks with greater than 90% felsic minerals can also be called leucocratic, meaning 'light-coloured'.

11. TECTONIC PLATES AND THEIR MOVEMENT
EARTHQUAKES
VOLCANOES

12. TYPES OF TECTONIC PLATE BOUNDARIES
Transform (slipping)
Divergent (spreading)
Convergent (subduction)

13. How do the plates move?

14. PLATES 2006 Atlas of Plate Reconstructions (750 Ma to Present Day)
By L.A. Lawver, I.W.D. Dalziel, and L.M. Gahagan
2007, University of Texas Institute for Geophysics
March 8, 2007
See Show

15. Why do the plates move?

16. WHY DO PLATES MOVE? 1 - DRAGGING
Inner Core – Lots of Heat (radioactive decay) ,700
Heat migrates thru inner & outer core, lower mantle, to the upper mantle
Heat circulates in the upper mantle, much like boiling water in a pot, and as it circulates, it drags the plates sitting on top it
Most of Earth's heat is stored in the mantle, and there are four sources that keep it hot.
First, there's the heat left over from when gravity first condensed a planet from the cloud of hot gases and particles in pre-Earth space. As the molten ball cooled, some 4 billion years ago, the outside hardened and formed a crust. The mantle is still cooling down. It only contributes 5 to 10 percent of the total
Next is gravitational heat from a gravitational sorting process called differentiation; the denser, heavier parts were drawn to the center, and the less dense areas were displaced outwards. The friction created by this process generated considerable heat and also contributes 5 to 10 percent of the total.
Then there's latent heat; this type arises from the core's expanding as the Earth cools from the inside out. Just as freezing water turns to ice, that liquid metal is turning solid—and adding volume in the process. "The inner core is becoming larger by about a centimeter every thousand years," The heat released by this expansion is seeping into the mantle.
Lastly, and most importantly, up to 90 percent—is fueled by the decaying of radioactive isotopes like Potassium 40, Uranium 238, 235, and Thorium 232 contained within the mantle. These isotopes radiate heat as they shed excess energy and move toward stability.

17. 3 Likely Circulation Patterns
Alternative 1:
2 Layer Convection?
Alternative 3:
Occasional Mixing?
Alternative 2:
Whole Mantle Mixes?
Crust
Upper Mantle
Lower Mantle
Core

18. Mantle Heat Convection Model
with Plate Subduction
Crust
Subduction Zone
Mantle
Heat Circulation
Core
See video

19. ANOTHER CAUSE OF MOVEMENT – SPREADING
At certain places on the Earth’s crust, there are cracks that extend all the way down to the upper mantle
Upper mantle material oozes from those cracks, forming new crustal plate material as it cools
This new plate material is pushed out of the way by new upper mantle material oozing out. This pushing motion causes the new material to “spread”
Older rocks
Older rocks
Younger rocks
ATLANTIC OCEAN

21. GEOLOGIC TIMESCALE 4 Principle Eon’s of Earth’s Time
Earth Formed
4650 mya
This is known as PRECAMBRIAN time
Only this time period is subdivided into details of Geologic Time

22. GEOLOGIC TIMESCALE

23. GEOLOGIC TIMESCALE

24. GEOLOGIC TIMESCALE

25. GEOLOGIC TIMESCALE

26. GEOLOGIC TIMESCALE

27. GEOLOGIC TIMESCALE

29. GEOLOGY OVERVIEW – Part 1 WHAT HAVE WE TALKED ABOUT?
Quick overview of earth’s geological makeup
Earth is approximately _____ miles in diameter; and approx what temp in the core ______deg F
There are ___ types of CRUST: the __________ & ________
The Crust is made up of ___ main plates; the largest is the _______ plate (this plate makes up the “Ring of Fire”)
____Types of plate boundaries: __________, __________, and
Due to Plate Tectonics, North America was ______ miles below the equator ______ mya
8,000
9,700 2
Continental
Oceanic 7
Pacific 3
Convergent
Divergent
Transform
2,000
600

30. GEOLOGY OVERVIEW – Part 1
Geology & Travel!
On to
REMEMBER…
GEOLOGY ROCKS

31. ANY QUESTIONS?? GEOLOGY OVERVIEW – Part 1
All class materials either is or
will be on
1) the University’s website
and on
2) Don’s Website at:
ANY QUESTIONS??