GEOLOGY 101 Exam 2 Texas A&M with Dr. Marcantonio

Lahar

mudflow originating from a volcanic slope, also called mass wasting events

What is a geological example of both a hot spot AND divergent plate boundary location?

Iceland

Where is magma generated?

Uppermost mantle

Where is the greatest amount of magma created?

At divergent plate boundaries. A lesser amount is formed at subduction zones. It can also be formed when crustal rocks melt.

Geothermal Gradient

When the temperature of in the upper crust increases about 25 degrees celsius per kilometer

What can cause rock to melt at lower temperatures?

Water and other volatiles

Bowen's Reaction Series

Minerals crystallize in a systematic fashion based on their melting points.

What is the first mineral to crystallize?

Olivine

At what point of a melt will there be very little iron, magnesium, and calcium?

When 1/3 of a magma has crystallized

Viscosity

measure of a material's resistance to flow

Which is more viscous... water or syrup?

Syrup

Name three factors that affect viscosity.

Temperature, composition, dissolved gases

Which is more viscous... magma with a high or low silica content?

Higher silica content such as with Rhyolite and Andesite and is considered felsic.

What minerals do lower viscous magmas contain?

Iron and magnesium. They are considered mafic.

Shield Volcano

Huge volcanos. Hawaii's Mt. Kilauea is an example.

Composite "Strato" Volcano

Has many layers of lava forming a very steep volcano cone.

Cinder Volcano

Smallest type of volcano.

What is the composition of lava flows?

90% basalt, less than 10% andesite, less than 1% rhyolite

What are the two types of basaltic lava flows?

Aa (rocky) and Pahoehoe (fluid and smooth)

Lava tubes

Cave like tunnels where lava flows

Block lava

Short detached blocks of lava

Pillow lava

Lava formed underwater that looks like toothpaste

What percent do gas volatiles make up of magma?

1 - 6%

What gases is magma composed of?

Water, carbon, nitrogen, sulfur, and others

Pyroclastic materials

Volcanoes eject pulverized rock and lava fragments from small fine dust, to sand sized and very large rocks

Tephra

Anything a volcano ejects into the air

Lapilli

Walnut sized volcanic ejection

Cinder

Pea sized volcanic ejection

Block

Hardened or cooled lava ejected that is less than 2.5 inches

Bombs

Streamlined, molten hot lava ejected greater than 2.5 inches

Pumice

Light gray or pink porous rock from frothy andesitic or rhyolitic lava

Scoria

Reddish brown porous rock from frothy basaltic lava

Fissure

Crack that develops in crust as magma moves toward the surface

Conduit

Circular pathway from fissure to surface

Vent

Surface opening of a conduit

Crater

Funnel shaped depression at summit less than 1 km

Caldera

Massive crater greater than 1 km due to huge eruption collapse

Parasitic cone

Flank vent, not the center vent

Fumaroles

Flank vent that emits gases

What are four general features of cinder cone volcanos?

Steep slope, small size, generally in groups, built from ejected lava fragments.

What are two examples of Cinder Cone volcanos?

Flagstaff, Arizona and Paricutin, Mexico

What are five general features of Composite Volcanos?

Large, classic shaped, symmetrical cone, thousands of feet high, several miles wide

What is another name for cinder cone volcanos?

Scoria volcanos

What is another name for Composite Volcanos?

Stratovolcanos

What are composite volcanos composed of?

Interbedded andesitic lava flows and layers of pyroclastic debris

Where do you find many composite volcanos?

The Pacific Ring of Fire

What are two examples of composite volcanos?

Mount St. Helens (USA) and Mount Etna (Sicily)

Nuee Arente

Pyroclastic flows

Which volcano created the "Year without summer"?

Mount Tambora, Indonesia 1815

Which volcano in Mexico created a huge carbon and sulfur cloud and what year was it?

El Chinchon in 1982

Weathering

Physical breakdown and chemical alteration of rock at Earth's surface

Mechanical Weathering

Physical forces break down rock into smaller pieces

Frost wedging

Water gets into a rock, freezes, and enlarges cracks

How does Salt crystal growth cause weathering?

Water gets into a rock, evaporates, but leaves behind salt to grow crystals that crack the rock

Sheeting

Igneous rock exposed due to erosion breaks lose in slabs due to release of confining pressure

What are two examples of sheeting?

Enchanted Rock and Half Dome

What are three ways biological activity cause weathering?

Plant roots grows and expands rock, animals burrow, human bust shit up

What are four types of mechanical weathering?

Frost wedging, salt crystal growth, sheeting, biological activity

Chemical Weathering

Chemical transformation of rock into new compounds

What is the number one agent of chemical weathering?

Water

What are three types of chemical weathering?

Dissolution, Oxidation, Hydrolysis

Dissolution

Minerals dissolve in water, small amount of carbonic acid in water is corrosive

What are two big components of dissolution

Halite and calcite

Oxidation

Rust. Chemicals are losing electrons

What two materials is oxidation specific to?

Iron and hematite

Hydrolysis

Reaction of any substance with water

What are the three major minerals in granite?

Quartz, potassium feldspar, plagioclase feldspar

What is the residual mineral left after granite is leached?

Clay

Leaching

Loss of soluble substances and colloids from the top layer of soil by percolating precipitation

What two things affect the rate of weathering?

Rock characteristics and climate

Which weathers faster... quartz or olivine?

Olivine

Which weathers faster... carbonates/halides or silicates?

Carbonates and halides

Which climate region weathers faster... tropical or cold?

Tropical

What is the bridge between life and the inanimate world?

Soil

Regolith

Layer of rock and mineral fragments produced by weathering

What is soil?

Combination of mineral and organic matter, water, and air which supports plants

What are six "controls" when considering soil?

Parent material, climate, plants, animals, time, topography

Residual soil

Soil formed on top of bedrock

Transported soil

Soil moved by floodplain

Eluviation

Transport of soil material from upper layers of soil to lower levels by downward precipitation of water across soil horizons

What is the order of soil layers by name?

OAEBC

Describe the process of water runoff.

Rain causes sheet erosion which becomes rills, then gullies and sediment is deposited into streams and rivers

What percent land area of the Earth does sedimentary rock cover?

75%

What percent ocean floor does sedimentary rock cover?

Almost 100%

What important economic resources does sedimentary rock contain? (There are nine)

Coal, oil, fossil fuels, uranium, iron, aluminum, manganese, phosphate, groundwater

What is the order of sedimentation?

Weathering, transport, deposition, burial, lithification

What are the three types of sedimentary rock?

Detrital, chemical, organic

Detrital

Mechanically weathered and physically transported sedimentary rock

What is the most common detrital sedimentary rock

Shale

What are four detrital sedimentary rocks

Shale, sandstone, conglomerate, breccia

Greywacke

Formed from turbidity currents, landslides under the ocean

What are three examples of Chert?

Flint, jasper, petrified wood

How is coal formed?

Plant remains form peat or lignite, then bituminous coal, and finally anthracite coal

Diagenesis

Chemical, physical, and biological changes that take place after sediments are deposited and occurs near the Earth's crust

Lithification

Unconsolidated sedimentary rock is transformed into solid sedimentary rocks through compaction and cementation with water

What causes bleaching of coral reefs?

Oceans warm and become more acidic, algae is stressed so it leaves, this removes the color and the reefs die

What are the three categories of sedimentary environments?

Continental, Transitional, Marine