13: Introduction to Landform Study

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13 Introduction to Landform Study
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Outline

• The Unknown Interior
• Composition of the Crust
• Critical Concepts
• The Study of Landforms
• Geomorphic Process, Scale, and Pattern

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1. The Unknown Interior

• Internal structure of the earth based on indirect
  evidence based on shock waves, magnetic
  properties and gravitational attraction
• Crust 1 in volume, 5-25 miles or 8-40 Km
• Mantle 1800miles
• Outer Core 3,100 miles
• Inner Core Fe, NI, Si 900 m

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1. The Unknown Interior

• Deepest mine 2.4 miles or 3.8 km
• Deepest core 12 Km , less than 8 miles
• How do earth scientists know what is inside?
• Geophysical means
• Monitoring shockwaves
• Shockwaves change speed and direction when they
  cross boundary from one type of material to the
  other

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1. The Unknown Interior
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Earths Crust and Mantle
Rigid
Hot easily deformed
Rigid
Figure 13-2
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Composition of the Crust

• Minerals, Rocks, and Bedrock
• Igneous Rocks Crystalline
• Sedimentary Rocks Stratified
• Metamorphic Rocks Changed under heat and pressure

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Minerals
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Common Rock-forming Minerals

• Silicates
• Oxides
• Sulphites
• Sulphates

• Carbonates
• Halides
• Native elements

OH! S3CN
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Bedrock
Buried Rock not exposed to erosion
Figure 13-4
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Igneous Rocks
Basalt
Granite
Figure 13-5(a)
Classified based on mineral composition and
texture Felsic High silicates
Mafic Low silicates
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Extrusive ( Volcanic) Igneous
Figure 13-6(a)
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Intrusive (Plutonic) Igneous
Figure 13-7(a)
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Sedimentary Rocks
Figure 13-5(b)
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Formation of Sedimentary Rocks
Consolidation of the deposited
Particles Cementation of particles
Figure 13-8
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Sedimentary Strata
Figure 13-10
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Relative Abundance Sedimentary Rock Types
Figure 13-11
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Metamorphic Rocks
Figure 13-5(c)
Slate and Marble
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Foliation
Figure 13-13(a)
An outcrop of banded Gneiss in Greenland
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The Rock Cycle
Figure 13-15
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Distribution of Rock Classes
Figure 13-16
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Critical Concepts

• Basic Terms
• Topography Surface Configuration of the Earth
• Geomorphology Characteristics of the origin and
  development of landforms
• Landform Individual topographic unit
• Relief Difference in elevation

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Critical Concepts

• Uniformitarianism The present is the key to the
  past
• Geologic Time Earth formed 4.6 Billion years
  ago, Dinosaurs persisted 160 m yrs ago
• Rocky mountain uplifted 65 m years ago.
• Theories of Rigid Earth has been questioned
• Assumed rigid, changes occurred because of sea
  level rise or mountain building
• Sima (Heavier) Oceanic Crust
• Sial (Lighter) Continental crust
• Isostasy lightweight granite floats on a
  foundation of basalt
• continents free to move

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Geologic Time
Figure 13-18
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The Study of Landforms

• Structure Nature, arrangement and
  orientation of material
• ProcessActions and forces that have
• operated to produce land forms
• Slope Fundamental aspect, balance of structure
  and process
• Drainage Movement of water

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Structure
Figure 13-19(a)
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Process
Figure 13-20
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Slope
Figure 13-21
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Geomorphic Processes
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Questions of geographic inquiry

• What forms of features
• Where are they (distribution and pattern)
• Why are they there. Explanation of origin
• So what? Significance of topography in relation
  to other elements of environment and human
  activity

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External and Internal Geomorphic Processes
Figure 13-22
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Scale
Close view
Looking down from the Road
Figure 13-B
Aerial View of the part of the range
North America from space
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Landform Distribution Pattern
Figure 13-23