Geology - Test 2

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Here are four terms. Two are basically synonyms of the other two. Which words match which? Intrusive Volcanic Plutonic Extrusive: Intrusive = Plutonic
Volcanic = Extrusive
How does "volcanic" differ from "plutonic"?: Volcanic is outside, cools quicker, aphanitic texture > small crystals

Plutonic is inside, cool slower, phaneritc texture > big crystals
How does "intrusive" differ from "extrusive"?: Intrusive - inside, plutonic, cools slowly, phaneritic texture, large crystals

Extrusive - outside, volcanic, cools quickly, aphanitic texture, small crystals
How does magma differ from lava?: Magma - is inside the earth

Lava - is outside the earth
How would you recognize aphanitic texture, and what does it indicate?: A rock with aphanitic texture would have cooled outside the volcano, very quickly, small crystals ---etc
Did a rock with aphanitic texture cool relatively quickly or relatively slowly? Is this rock more likely to be intrusive or extrusive?: A rock with aphanitic texture cooled relatively quickly, it is more likely to be extrusive
Did a rock with phanertic texture cool relatively quickly or relatively slowly? Is this rock more likely to be intrusive or extrusive?: A rock with phanertic texture cooled relatievly slowly, it it more likely to be intrusive
Explain what "viscosity" means.: a measure of a fluid's resistance to flow
Name and explain the factors that control a magma's or lava's viscosity.: -Silica (SiO2) Content of magma
- -more silica = more viscosity

-Temperature of magma
- -hotter = less viscous = more flows

-Amount of dissolved gases (volatiles) in melt
Why is basaltic lava more fluid than rhyolitic lava?: Basaltic lava is hot, has not a lot of volatailes, low viscosity!, safe!

Rhyolitic lava - cooler, high silica=thick, lots of volatiles, crazyness!
What is pahoehoe? Describe it.: Pahoehoe, from shield volcano, basalt, near vent, ropey like taffy
What is aa? Describe it.: Basalt, shield volcano... Aa, is downstream, blocky flow, rocky --pretty safe if you ask me
Name at least 4 states in the U.S. where there are substantial basaltic lava flows.: Hawaii, Washington, Oregon, Idaho
How does a volcanic dome form?: ?
What is a shield volcano?: produced by the accumulation of fluid basaltic lavas and exhibit the shape of a broad slightly domed structure that resembles a warrior's shield
What kind of lava erupts from shield volcanoes?: pahoehoe and aa --- Mafic (basaltic) magma, (little silica content 50%)m least viscosisty...very fluid... little gas content (1-2%), don't form pyroclastics
Does the lava erupting from shield volcanoes have relatively high or relatively low viscosity?: low (it's very fluid)
Does the lava erupting from shield volcanoes ordinarily have relatively high or relatively low volatile content?: shield volcanoes have a relatively low volatile content
Does the lava erupting from shield volcanoes have relatively high or relatively low silica content?: shield volcanoes usually have a low silica content
Does the lava erupting from shield volcanoes have relatively high or relatively low temperature?: basaltic lava flows are hot!
Are shield volcanoes generally among the most hazardous volcanoes or among the least hazardous volcanoes? Why?: shield volcaues are least hazardous because the gently bleed of the volatiles
Which U.S. state consists almost entirely of basaltic lava?: Hawaii
Which type of volcano is generally very tall and steep-sided and produces large amounts of pyroclastic material as well as lava flows?: Andesite Volcanoes ---- tall steep --layered structures are called stratovolcanoes or or composite cones
On average, which type of lava (give a rock name) is produced by stratovolcanoes (composite cones)?: eruptions alternate between
-dangerous pyroclastic eruptions
- gentler flows after volatiles have bled off...

i think it's andesite...?
Which type of volcano has caused the most destruction to cities?: Stratovolcanoes eruptions have produced worst volcanic disasters to affect humans...strato also known as Andesite also called...composite cones
What is it about stratovolcanoes that makes them so dangerous?: *haveing lots of ash to inhale
*large rock fragments
*may generate a mudflow "lahar"
*the stuff "Nuee Ardente" or glowing avanlanches go fast!
Which type of lava is the most viscous?: Felsic, or Rhyolitic, magma is most viscous
Which type of lava is the coolest (although still very hot!)?: Rhylotic lava is the coolest...
Where in the U.S. can you find a mountain chain composed of stratovolcanoes? Name the mountain chain. Name a couple of U.S. cities that may be threatened by these stratovolcanoes.: ?
Describe and distinguish the three types of volcanoes by size, shape and components.: Basaltic -
Andesite -
Rhyolitic -
Describe in words and a sketch how and why andesitic volcanoes are associated with subduction zones: ?
Describe a nuee ardente.: a pyroclastic flow that consists of hot gases infused with incasdescent ash and larger rock fragments... very distructive
What is a lahaar and how does it form?: --mudflows on active and inactive cones--

occur when volcanic debris becomes saturated with water and rapidly moves down steep volcanic slopes, generally follwing gullies and stream valleys. and other things can trigger it...
can occur when volcano is NOt erupting
Is rhyolitic lava relatively high or relatively low in silica?: Rhyolitic (felsic) lava is relatively high in silica (70%)
Is rhyolitic lava relatively viscous or relatively fluid?: Rhyolitic lava has the greatest viscosity content of all the magmas
Is rhyolitic lava relatively rich in volatiles or relatively poor in volatiles?: Rhyolitic lava has the highest volatile content (4-6%)
Is rhyolitic volcanism relatively violent or relatively placid? Why?: ?
Mt Ranier ---What type of volcano is this? On average, what kind of lava (rock name) does this volcano erupt. Is this type of volcano among the most hazardous on Earth, or among the least hazardous on Earth? Explain WHY this volcano is or is not particul: ?
If you went hiking in Yosemite National Park, what kind of rocks (rock name) would you chielfy see? Where is Yosemite National Park? What is the mountain range of which it is a part?: ?
What 2 types of volcanoes are made by basaltic lava?: Shield Volcanoes and Cinder Cones
What type of volcano is Mauna Loa and of what type of rock is it made?: shield --- basalt
Where is Mt. Rainier and what type of volcano is it? What is its average composition (rock name)?: Composite cone - andesite
What is columnar jointing in basalt?: five-to-seven sided columns are produced by contraction and fracturing that occurs as a lava flow or sill gradually cools (can be seen in Giants Causeway National Park, Northern Ireland)
Large volcanic eruptions have been linked to temporary climate change. What is the nature of the climate change? Explain how the eruptions cause the climate change.: Climate cooling ...
*volcanoes emit sulfurous gas that turns into crystals of sulfuric acid ice in upper atmosphere
*sulfuric acid ice crystals reflect warming sunlight back into space
-1815, after eruption of Tambura (indonesia), was "year without summer"
What is a roof pendant?: ?
What is the difference between a Â“batholithÂ” and a Â“stockÂ”: a batholith is big
a stock is little
Explain the difference between Â“weatheringÂ” and Â“erosionÂ”?: Weathering is the chemical, physical break down of rocks, minerals, near earth's surface

Erosion - process of removing weathered material from immediate site of weathering
Explain the process of Â“frost wedgingÂ” and tell where it is an effective and significant geologic process altering the landscape: frost wedging is repeated cycles of freezing cycles of freezing and thawing represent an important process of mechanical weathering.

usually seen in mountainous regions
Explain how an exfoliation dome forms, and give the name and location of an actual one.: ?
Explain how clay minerals are produced in nature.: through hydrolysis of host solution
Explain how mechanical weathering assists chemical weathering and give an example of this in nature: because chemical weatheriung can occuor only to the portions of rock that are exposed, mechanical weathering breaks rock into smaller and smaller pieces, therby increasing the surface area available for chemical ATTACK
List the four components of a typical soil: 25% air
25% water
45% mineral matter
5% organic matter
Explain the zone of leaching and the zone of accumulation in soil.: ?
What is the name for a type of soil containing an accumulation of calcium carbonate in the B horizon?: ?
What is caliche?: ?
Which type of soil is prevalent in arid and semi-arid regions of the U.S.?: Pedocal - accumulation of calcium carbonate etc.etc. thing caliche,
Which soil type is most common in more humid regions of the U.S.?: Pedalfer - more than 25inches of rain
Which soil type is most common in the hot, wet tropics?: Laterite - contrations of iron and aluminum oxides
In the "big picture", one type of soil dominates in the U.S west of the Mississippi River, and another type of soil dominates east of the Mississippi River. What are the two types of soils, and why is there a geographic difference?: east - pedalfer
west - pedocal

?
What distinguishes a soil from a regolith?: "With few exceptions, Earth's land surface is covered by regolith, the layer of rock and mineral fragments produced by weathering"

Soil is a combination of mineral and organic matter?
Why are clays so common in soils and sedimentary rocks?: ?
How do all sedimentary rocks form?: ?
What is diagenesis? Which processes are included in diagenesis?: ?
Outline the classification scheme for all sedimentary rocks.: ?
What are some characteristics of a mature sedimentary rock? Of an immature sedimentary rock?: ?
What is the essential difference between breccia and conglomerate?: Conglomerate is composed primarily of rounded gravel-size particles

Breccia has angular particles
What is the basis for naming detrital sedimentary rocks?: size and type of particles
What is the difference between gravel and conglomerate?: gravel is the stuff it's made out of, conglomerate is the actual rock
What is the difference between shale and clay?: shale is the rock, clay is the stuff it's made out of
Which minerals dominate (to varying degrees) in practically all detrital sedimentary rocks?: clay minerals...and quartz
Which is the most abundant detrital sedimentary rock, and why?: Shale
What are some common cements in sedimentary rocks? What do the cements do?: ?
What is coquina?: a rock :) consists of shell fragments,(it has a biochemical origin), it's a biochemical limestone
What is chalk?: Chalk is a soft prous rock made up almost entirely of the hard parts of microscopic marine organisms smaller than the head of a pin
Name some sedimentary rocks that are (or may be) evaporites. How do evaporites form?: ?
What is a "stratum" or "bed"?: the single most ommon and chgarcteristic feature of sedimentary rocks...
When in the history of a sediment or sedimentary rock do sedimentary structures form? Why are we interested in sedimentary structures?: ?
Explain how you can tell the difference between oscillation ripple marks and current ripple marks.: Current ripple marks - steeper slopes, in downward direction and more gradula slopes on upside...by sandy channel or wind clowing

Oscillation - symmetrical form, result from the back and forth movement of surfcae waves in a shallow nearshore environment
How are desiccation cracks produced? Name a sedimentary environment where you could find desiccation cracks that formed recently.: ?
What is a turbidity current? What kind of sedimentary structure is associated with deposition from turbidity currents?: graded beds ----think underwater landslide, graded beds are just like the big stuff at the bottom small stuff at the top
What is the primary basis used to classify detrital sedimentary rocks?: by the particles or sediment it's made up of
What is the chief mineral in most sandstones?: quartz?
Explain why the sand grains on many ocean beaches are dominated by quartz, rather than by any of the other common minerals the continents are made of.: it's stable and stuff...
How do all metamorphic rocks form?: preexisting rock is subjected to temperatures and pressure unlike those in which it formed
What is the literal meaning of the word "metamorphism"?: "change form"
What are the agents of metamorphism? That is, what causes metamorphism? Be complete.: ?
Outline the classification scheme for metamorphic rocks.: ?
What is "foliation"?: refers to any planar (nearly flat) arrangement of mineral grains or structural features within a rock
What is a "protolith"?: ?
What does "metamorphic grade" refer to?: ?
How does "marble" fit into the classification scheme for metamorphic rocks? Name a likely protolith of marble.: non foliated, limestone
What is the most conspicuous and distinguishing feature of gneiss?: banding
Which metamorphic rock is characterized by its large flakes of mica?: ?
How could you recognize a phyllite?: ?
What is "contact metamorphism" and what is a contact metamorphic "aureole"?: ?
What conditions lead to regional metamorphism?: ?
Consider what marble is made of, and then use this information to work out a way you might identify it by ordinary testing if you weren't sure.: hcl (calcite)

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