Geology

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Geology

• PSCI 120

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Layers of the Earth

• Inside the earth this dynamic earth, USGS
• Read this page from the US geological survey and
  fill in pages 1 and 2 in your student guide

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How Do We Know?
NOT by drilling holes! (Not that we dont
try) We map the structure of Earth by measuring
seismic waves.

• Holes
• Mohole project
• Ocean drilling program
• Digging from China

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Seismic Wave Pattern

• Patterns of earthquake (seismic) waves as they
  arrive at seismograph stations worldwide
• P-waves (primary)
• Propagate through solids and liquids, but change
  speeds
• S-waves (secondary)
• Propagate through solids but not liquids

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Seismic Wave Types
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Mapping Inner Earth
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Review

• T or F In 1999, with NSF funding, a hole was
  drilled into the mantle.
• T or F Scientists have mapped the interior of
  Earth by taking core samples.
• Which type of seismic wave dies out when it hits
  a liquid boundary?
• Give 3 characteristics of a P-wave.
• Give 3 characteristics of an S-wave.

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Field Guide to Rocks and Minerals

• Are rocks and minerals the same thing?

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What Is A Mineral?

• A mineral is a naturally occurring inorganic
  solid with definite chemical composition and
  crystal structure.
• Gypsum CaSO4.2H20.
• A minerals appearance will depend on the
  conditions under which it was formed.

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Another Mineral
CaCO3
Limestone
Marble
Calcite
Aragonite
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What Is a Rock?

• A rock is a mixture of minerals

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Types of Rock

• Sedimentary
• Igneous
• Metamorphic

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Sedimentary Rock
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Types Of Sedimentary Rock

• Clastic (cemented) sediments
• 1. Weathering (breaking down) rocks into small
  particles
• 2. Deposition (laying down) of these particles
• 3. Cementation (consolidation, glue)
• Chemical sediments
• Organic sediments

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Clastic Sediments

• Shales
• Fine grained particles of clay
• Deposited in deep water
• Sandstones
• Larger grained sand particles
• Deposited near shores
• Conglomerates
• Pebbles, large sand grains

Western Kansas
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Organic Sediments

• Limestone
• Consists mainly of animal shells left on ocean
  floors, lake bottoms or river beds
• Type of limestone depends on minerals in the
  water where it was formed
• Coal
• Decomposed vegetable matter

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Kansas City Rock Layers
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Chemical Sediments

• Weathered mineral-bearing rock dissolved in water
• Gypsum
• Salt
• Chert

Flint Hills Chert, Limestone
Salt mine Hutchinson, KS
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Student Activity

• Write three examples of sedimentary rock

Castle Rock, Western Kansas (chalk formation)
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Igneous Rock
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Igneous Rocks

• Rocks which form directly from the cooling of
  magma
• Igneous rock can form deep in the earth, on the
  surface of the earth or in the air
• The rate of cooling determines the crystal
  structure of the rock

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Basalt

• Very common fine-grained volcanic rock
• Rapid cooling forms fine-grained crystal
  structure
• Basalt is made of the minerals
• Feldspar
• Pyroxene
• Olivine
• Magnetite
• Remember rock is a mixture of minerals!

Devils Tower, Wyoming
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Granite

• Large individual crystals form when the rock
  cooled slowly, allowing time for crystal
  formation
• Granite consists mostly of the minerals
• Quartz
• Feldspar
• Mica

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Pumice

• Magma that cools very quickly in air
• Ejected in pyroclastic flows
• Very fine-grained
• Gas trapped inside

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Common Elements in Igneous Rock

• Magma is rock soup composed of the same elements
  that make up the crust and mantle of earth
• Oxygen, Silicon, Aluminum, Iron, Magnesium,
  Calcium, Sodium and Potassium
• Small quantities of rarer elements
• These elements combine differently to make
  various minerals quartz, feldspar, mica,
  amphibole, pyroxene and olivine.
• The minerals formed from the magma soup depend on
  where and how it is cooled.

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Student Activity

• Write three examples of igneous rocks

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Metamorphic Rock
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Metamorphic Rock

• Formed from igneous or sedimentary rock
• Heat
• Pressure
• Hot mineral solution
• Mineral composition changes
• Limestones gt marble
• Shales gt slate gt schist gt gneiss
• Sandstones gt quartzite

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Progression of Metamorphic Rock
Temperature and Pressure
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Student Guide Activity

• Write two examples of metamorphic rock
• Include the original and the product

marble
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Rock ProcessesWeatheringErosionDeposition
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Weathering, Erosion, Deposition
These three processes form all of the landscape
we have around us.
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Chemical Weathering

• Rainwater combines with CO2 in the atmosphere to
  form a weak acid
• Limestone layers are dissolved and deposited in
  caverns

Lewis Clark Caverns, Missouri
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Mechanical Weathering

• Wind carrying sand particles
• Water freezing/thawing in rock crevices
• Streams carrying abrasive particles, flooding

Concretions Western Kansas
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Biological Weathering

• Lichens
• Plant and tree roots
• Animal burrowing

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Erosion

• The process of moving weathered material from one
  location to another
• Water
• Wind
• Ice

Red Hills, Western Kansas
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Continental Glaciers

• Ice age continental glaciers scraped and ground
  surface rocks
• Created rolling hills and valleys, deposited
  glacial debris

Glacial Debris, Northwest Kansas
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Alpine Glaciers

• Smaller, year-round streams of ice
• Wears down upper mountain material and carries it
  downward into streams and valleys

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Erosion by Water

• Sediment carried by rains into streams
• Fast flowing water scours stream banks
• As the water slows, sediment settles
• Heavy particles first
• Silt and small particles last

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Deposition

• Sediments are deposited where
• Winds die down or are blocked
• Water slows down
• River bends
• Seas
• Glaciers stop or begin to melt

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The End