Geology Test 2

Geology 1100 with Molina at University of Missouri- Columbia

About this deck

By: Robert Custer
Created: 2011-10-03
Size: 42 flashcards
Views: 39

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Lava Flows

Molten rock that flows over the ground

Pyroclastic Debris

Fragments blown out of a volcano

Volcanic Gases

Vapor and aerosols that exit a volcano

Silicic, Felsic, or Rhyolitic

Lava with high Silica, low Fe and Mg

Mafic or Basaltic

Lava with low Silica, high Fe and Mg

Intermediate and andesitic

Lava with moderate levels of Silica, Fe and Mg

Basaltic Lava Flows

Mafic Lava (very hot and slow)

Thin fluid, run fast and long

Pahoehoe

Glassy ropy textured lava

Forms when extremely hot basaltic lava forms a skin

A'a'

Jagged, sharp, angular lava

Forms when basaltic lava cools, thickens, and crumbles

Andesitic Lava Flows

Higher SiO2 make flow more viscous

Mound around vent and flows slowly

Outer crust fractures creating rubble

Rhyolitic Lava Flow

Highest SiO2 and most viscous

Rarely flows, usually just plugs top

Sometimes lava domes are blown off

Pyroclastic Flows

Avalanches of hot ash

Kill everything in their path

200 - 450 C and up to 300 k/hr

Tephra

Deposits or Pyroclastic debris of any size

Tuff

Lithified (cemented) Ash

Air-fall, falls like snow

Ignimbrite, deposited while hot

Volcanic Gas

Up to 9% of magma can be gas

Low viscosity = easy escape, mellow eruption

High viscosity = difficult escape, violent eruption

Gas bubbles are called vesicles

Severity of shaking and damage depends on...

Magnitude

Distance from hypocenter

Intensity and duration of vibrations

The nature of subsurface material (bedrock transmits quickly = less damage, sediments bounce waves = amplified damage)

Liquefaction

Waves liquefy H2O filled sediments

Ground becomes like quicksand

Land will slump and flow

Tsunami Waves

When earthquakes change the seafloor

Normal faulting drops the seabed; thrusting raises it

Tsunami Behavior

Tsunamis race at jetliner speed across the ocean

As water shallows, waves slow from frictional drag

Since waves are so long the front slows growing the wave in height as water shallows

How Igneous rocks form

The solidification of molten rock (magma)

Sedimentary Rocks

Cementing together of grains broken off preexisting rocks

Precipitation of mineral crystals out of water

Metamorphic Rocks

Form when preexisting rocks change character due to change in pressure and temperature conditions, and/or applied forces (squashing, stretching, or shear)

Shield Volcanoes

Broad, slightly domed-shaped

Made by lateral flow of low-viscosity basaltic lava

Have a low slope and cover large geographic areas

Cinder Cone

Conical piles of tephra

Smallest type of volcano

Built of ejected lapilli-sized fragments piled up at a vent

Often symmetrical with a deep summit crater

Stratovolcanoes (Composite volcanoes)

Large, cone-shaped volcano

Composed of alternating layers of lava and tephra

Often symmetric; can be odd shapes from landslides, etc

Effusive Eruptions

Lave flows stream away from vents

Lava lakes can form around the vent

Can produce huge lava fountains

Commonly basaltic, create shield volcanoes

Explosive eruptions

Produce pyroclastic flows

Caused by gas pressure in more viscous magma

Pressure is released explosively

Create stratovolcanoes and possible calderas and lots of tephra

Viscosity

Controls the ease of lava flow

Basalt = low, lava flows away from vent

Felsic = high, lava builds up at vent

Gas Pressure

Greater P favors explosive style

Basalt = low viscosity allows gas release

Felsic = high viscosity prevents gas release

Convergent Boundaries

Most volcanoes form here

Lapilli

Volcanic fragments that fall around the volcano

Can completely bury landscapes killing plants and crops

Material is heavy and gritty

Blast

Rare, explosions ejecting sideways from a volcano

Lahars

Mudflows resulting when ash is moved by water

Like concrete, material is more dense than water

Felsic, Intermediate, Mafic, Ultramafic

Put in order:

Ultramafic, intermediate, felsic, mafic

Continental - continental and transform faults

What faults will you never find a volcano

Clastic

Made from weathered rock fragments

Type of sedimentary rock

Biochemical

Cemented shells or organism

Type of sedimentary rock

Chemical

Minerals that crystallize directly from water

Type of sedimentary rock

Ex. Salt (halite) and gypsum

Organic

The carbon-rich remains of plants

Type of sedimentary rock

Ex. Coal/Oil shale

Clash (grain) size

Range from very course to very fine

Boulder, cobble, pebble, sand, silt, and clay

With increasing transport grain size decreases

Biochemical limestone

Warm, tropical, shallow, clear, oxygen rich marine water

Diverse organisms - fossils

Cross Beds

Created by ripple and dune migration

Sediment moves up gentle side and then falls down steep slope

About this deck

By: Robert Custer
Created: 2011-10-03
Size: 42 flashcards
Views: 39

About StudyBlue

“Simply amazing. The flash cards are smooth, there are many different types of studying tools, and there is a great search engine. I praise you on the awesomeness.”
Dennis