Glaciers and glaciation.

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70% of the world's fresh water in held in glaciers

Running water is mostly responsible for shaping Earth's land surface.

Glaciers are far more effective agents of erosion, transportation, and deposition.

Ice Age glaciation

nondescript valley

Paleozoic glacial age

A glacier is a large, long-lasting mass of ice, formed on land, that moves under it's own weight. It develops as snow is compacted and crystallized. Glaciers can develop any place where, over period of years, more snow accumulates that what melts away or what is lost.

Are there types of glaciers? If so, what are they?

These are the types of glaciated terrain on Earth's surface.

1. Alpine glaciers is found in mountainous regions.
2. Continental glaciers exists where a large part of a continent is covered by glacial ice.

Types of Glaciers

1. Valley glacier - valley, high to low elevation, prevalent in areas of alpine glaciation
2. a. Ice sheet - covers a large area of mass, continental glaciation, Greenland and Antarctica
    b. Ice cap - smaller ice sheet
Both flows downward and outward from a central high point. Like a negative lava.

1/10th of land surface are covered by glaciers

1/3rd peak during glacial ages

Where are the glaciers?

85% Antarctic melt: 65 m (213 ft) rise
10% Greenland
5% others (freshwater)

How do glaciers form?

Just a process of compaction and crystallization.

It starts with a single snowflake. Snowflakes pile up they form a granular flow, glue multiple granular flow you get a firn, it's basically a snowball, then pile up a bunch of snowballs, you get a glacier ice.

Ablation is ice flow just as chocolate melts.

Sublimation is a process in which ice evaporates directly to the atmosphere.

Calve is ice break off. A divorce of ice.

Glacial Budgets

+ positive expand = advancing glaciers
- negative shrinks = receding glaciers
_ balanced budget

Zone of accumulation - up G
Zone of ablation - down G
-ice is ablated, evaporated, melted, called
Equilibrium line - snow line, firn line, boundary line

Terminus - lower edge of a glacier
* valley glacier
+ T down
-  T up

However, an advancing glacier doesn't mean it's getting colder, it just means that it's getting wetter, more precipitation is falling during the winter months, or the summers are cloudy, that means reducing the warmth of sunlight passing through.

5°C lowering will mean new ice age

How do glaciers move?

Less than few mm to 15 m in a day

Even glacier gradient has the thickest near equilibrium line.

Fastest moving ice near equilibrium line.
Slow after  E.L.

Faster in temperate climate than colder ones.

Surface moves faster than base.

Basal sliding is the sliding of the glacier as a single body over the underlying rock. Just like melting ice cream placed on a surface.

Plastic flow - movement of ice grains which they slide past one another though both grains move at the same time as one body.

Rigid zone - rigid movement, ice grains move as one though still aligned with the adjacent ice grains.

Crevasses - open fissure, develop also in curve path

Outlet glaciers - where mountain ranges are higher than the ice sheet, the ice sheet flows between mountains as valley glaciers

Ice streams - faster movement than in adjoining ice, which is frozen to it's bed, like a corpse

Glacial Erosion

Plucking - water will percolate to the rock cleavage then it will freeze again, and as the glacier move, it breaks and erode the rock underneath, more like a nose pack for rocks

Faceted - a surface formed through ablation

Striated - scratched

Rock flour - rock to rock grinding

Glacial Valleys

U-shaped valley, glacial erosion

V-shaped valley, stream erosion

Hanging valleys - higher than main valley, a toilet bowl sliced by a samurai

Truncated spurs - ridges with triangular facets produced by glacial erosion at lower ends

Cirque - steep-sided, half-bowl-shaped recess carved into a mountain at the head of a valley carved by a glacier, a half-eaten cupcake

Horn - sharp peak that remains

Aretes - sharp ridges, separate adjacent glacially carved valleys

Glacial Deposition

Till - the unsorted and unlayered rock debris carried or deposited by a glacier

Erratic - ice-transported boulder that has not been derived from underlying bedrock, wandering rock

Moraines - the till that occurs as a body of unsorted and unlayered debris either on the glacier itself, or what has been left by the glacier, think of a giant glacier worm devouring rock debris and excrete it as it moves, the poop is the moraine

Medial moraine - adjacent lateral moraine join and carried as a long ridge of till

End moraine - a ridge of till that piles up along the front edge of the ice, crescent-shaped or horshoe-shaped

A. Terminal moraine - end moraine marking the farthest advance of a glacier

B. Recessional moraine - end moraine built while terminus of a receding glacier remains temporarily stationary

Ground moraine - thin blanket of till

Drumlins - bodies of till shaped into streamlined hills, shaped like an inverted spoon

Outwash - material deposited by the debris-laden meltwater

Esker - an outwash feature of unusual shape associated with former ice sheets and some very large valley glaciers; a long, sinuous ridge of water-deposited sediment, pronounced: esssker, serpent kame

Kettle - it is formed when the ice block finally melts

Kame - low mound or irregular ridge formed or outwash deposits of stagnating glacier

Kame and kettle topography

Varve - two layers of sediment representing one year's deposition in a lake

Pluvial lakes - formed in a period of abundant rainfall

Fiord - a coastal inlet that is drowned glacially carved valley

Tillite - lithified till

Physical Geology 10 | Chapter 3

http://highered.mheducation.com/sites/007252815x/information_center_view0/index.html
http://highered.mheducation.com/sites/007252815x/student_view0/index.html
http://highered.mheducation.com/novella/SITELIBDisplay.jsp?mode=SEM&catId=903

1 A surface separating different types of rocks is called:

A) a chill zone.

B) a xenolith.

This is the correct answer.
C) a contact.

D) none of the above



2 The major difference between intrusive and extrusive igneous rocks is:

A) the type of minerals they contain.

This is the correct answer.
B) where they solidify.

C) their chemical composition.

D) all of the above



3 Which is not an intrusive rock type?

This is the correct answer.
A) andesite

B) granite

C) diorite

D) gabbro



4 By definition, stocks differ from batholiths in:

A) elevation above sea-level.

B) chemical composition.

C) shape.

This is the correct answer.
D) size.


5 On average, the geothermal gradient is about:

A) 50 degrees Celsius per kilometer.

This is the correct answer.
B) 30 degrees Celsius per kilometer.

C) 10 degrees Celsius per kilometer.

D) 1 degree Celsius per kilometer.



6 Which of the following minerals is part of Bowen's Continuous Series?

This is the correct answer.
A) plagioclase.

B) amphibole.

C) biotite.

D) pyroxene.



7 Which of the following minerals is part of Bowen's Discontinuous Series?

A) olivine

B) biotite

C) pyroxene

This is the correct answer.
D) All of these are part of Bowen's Discontinuous Series.



8 The difference in texture between plutonic and volcanic rocks is caused by:

A) different chemical compositions.

B) different amounts of water in the magma.

This is the correct answer.
C) different rates of cooling and crystallization.

D) different mineralogy.



9 A change in magma composition due to melting of surrounding country rock is called:

A) differentiation.

B) crystal settling.

This is the correct answer.
C) assimilation.

D) magma mixing.



10 Andesite is most often associated with what type of plate boundary?

A) reversible plate boundaries

This is the correct answer.
B) convergent plate boundaries

C) transform plate boundaries

D) divergent plate boundaries


11 You discover a rock with minerals large enough to be seen containing amphibole, biotite, and plagioclase. This is:

A) hornblende.

B) granite.

C) gabbro.

This is the correct answer.
D) diorite.



12 Bowen’s Reaction Series illustrates relations between:

A) temperature, pressure, and viscosity.

B) viscosity, temperature, silica content, and volatile content.

This is the correct answer.
C) temperature, chemical composition, and mineral structure.

D) temperature, viscosity, and mineral composition.



13 The two important criteria used for igneous rock classification are:

This is the correct answer.
A) texture and mineral composition.

B) temperature and viscosity.

C) mineral composition and temperature.

D) texture and temperature.


14 Basalt and gabbro:

A) formed from magma with the same silica content.

B) formed from magma with the same temperature.

C) have the same minerals.

This is the correct answer.
D) all of these



15 A rock with mineral crystals too small to be seen and low temperature minerals is:

A) granite.

B) andesite.

This is the correct answer.
C) rhyolite.

D) gabbro.



16 Igneous rocks that form entirely beneath Earth's surface are said to be:

A) platonic.

This is the correct answer.
B) plutonic

C) extrusive.

D) volcanic.



17 Andesite was named for a rock type commonly found:

A) in Mayberry, North Carolina.

This is the correct answer.
B) in the Andes Mountains.

C) in Hawaii.

D) in the Rocky Mountains.



18 Igneous processes are those which relate to:

A) solidification of magma.

B) formation of magma.

C) melting of rocks.

This is the correct answer.
D) all of these


19 The geothermal gradient of the asthenosphere is:

A) always changing as a result of plate tectonics.

B) the reverse of the geothermal gradient in the lithosphere.

This is the correct answer.
C) about 1 degree per kilometer.

D) the same as the temperature structure of the lithosphere.



20 Volcanic rocks are also:

A) Explosive.

This is the correct answer.
B) Extrusive.

C) Plutonic.

D) Intrusive.

1 CORRECT All igneous rocks form from magma.

This is the correct answer.

A) TRUE

B) FALSE

Feedback: CORRECT!

2 CORRECT All volcanic rocks are also igneous rocks.

This is the correct answer.

A) TRUE

B) FALSE

Feedback: CORRECT!

3 CORRECT All igneous rocks are composed of minerals.

A) TRUE

This is the correct answer.

B) FALSE

Feedback: CORRECT!

4 CORRECT Igneous rocks with fine-grained texture are also plutonic.

A) TRUE

This is the correct answer.

B) FALSE

Feedback: CORRECT!

5 CORRECT Igneous rocks that contain olivine solidified at relatively high temperatures.

This is the correct answer.

A) TRUE

B) FALSE

Feedback: CORRECT!

6 CORRECT Bowen's Reaction Series is a key to understanding igneous rocks.

This is the correct answer.

A) TRUE

B) FALSE

Feedback: CORRECT!

7 CORRECT Bowen's Discontinuous Series contains minerals with similar silicate structures but different chemical compositions.

A) TRUE

This is the correct answer.

B) FALSE

Feedback: CORRECT!

8 CORRECT The size of mineral grains in an igneous rock reveals information about the cooling history of the magma.

This is the correct answer.

A) TRUE

B) FALSE

Feedback: CORRECT!

9 CORRECT By definition, volcanic rocks are those extruded onto Earth's surface.

This is the correct answer.

A) TRUE

B) FALSE

Feedback: CORRECT!

10 CORRECT Pressure is an important variable controlling the formation of magma.

This is the correct answer.

A) TRUE

B) FALSE

Feedback: CORRECT!

11 CORRECT Temperature is an important variable controlling the formation of magma.

This is the correct answer.

A) TRUE

B) FALSE

Feedback: CORRECT!

12 CORRECT Olivine is the first mineral to form in Bowen's Continuous Series.

A) TRUE

This is the correct answer.

B) FALSE

Feedback: CORRECT!

13 CORRECT In Bowen's Discontinuous Series, more complex silicate structures form as temperature decreases.

This is the correct answer.

A) TRUE

B) FALSE

Feedback: CORRECT!

14 CORRECT All igneous rocks form from magma with the same composition.

A) TRUE

This is the correct answer.

B) FALSE

Feedback: CORRECT!

15 CORRECT Magma formation is common at divergent plate boundaries.

This is the correct answer.

A) TRUE

B) FALSE

Feedback: CORRECT!

16 CORRECT Deep inside Earth where temperatures are very high, all rocks have melted to form magma.

A) TRUE

This is the correct answer.

B) FALSE

Feedback: CORRECT!

17 CORRECT Andesite is a common igneous rock found in the Andes Mountains of South America.

This is the correct answer.

A) TRUE

B) FALSE

Feedback: CORRECT!

18 CORRECT Some magmas are cool enough for you to touch with your bare hand.

A) TRUE

This is the correct answer.

B) FALSE

Feedback: CORRECT!

19 CORRECT The most common igneous rock in the ocean basins is basalt.

This is the correct answer.

A) TRUE

B) FALSE

Feedback: CORRECT!

20 CORRECT All volcanoes in North America are extinct.

A) TRUE

This is the correct answer.

B) FALSE

Feedback: CORRECT!

NOTE: CONTINUOUS VS DISCONTINUOUS

The continuous branch describes the evolution of the plagioclase feldspars as they evolve from being calcium-rich to more sodium-rich.

The discontinuous branch describes the formation of the mafic minerals olivine, pyroxene, amphibole, and biotite mica.

TERMS:

http://geology.com/minerals/plagioclase.shtml

maf·ic = relating to, denoting, or containing a group of dark-colored, mainly ferromagnesian minerals such as pyroxene and olivine


*PLUTONIC ROCKS are rocks beneath the Earth's crust which is a solidified magma while a volcanic rock is a solidified lava.

The name was taken from the God of the Underworld, Pluto or Hades