Introduction to Landform Study Chapter 13

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1 Introduction to Landform Study Chapter 13

2 Geomorphology The study of the characteristics, origin, and development of landforms 58 million square miles of land 7 continents Wide latitudinal range and environmental conditions Surface obscured by vegetation and human projects

3 The Study of Landforms Landform - an individual topographic feature of any size hill, cliff, sand dune, peninsula, mountain range

4 Geologic Time The Earth is 4.6 billion years old Relative time What happened in what order Absolute time Actual number of year before present Radiometric dating Uniformitarianism The same physical processes active today have been active throughout geologic time Landslides, earthquakes, volcanic eruptions, asteroid impacts, mountain building, glaciers 4

5 Precambrian Most of the age of Earth Formation of atmosphere Formation of the moon First life 3.5 billion ya Mesozoic Age of dinosaurs million years ago Major extinctions mark beginning and end Pleistocene Last major ice age First humans 1.8 million ya Holocene Current epoch 11,500 years Retreat of Pleistocene glaciers 5

The Structure of the Earth Formed from dust, gas and comets Gravity sorted materials into layers No person has penetrated more than 1/1000 th of the distance

6 The Structure of the Earth Formed from dust, gas and comets Gravity sorted materials into layers No person has penetrated more than 1/1000 th of the distance to the center of the earth Drill hole - 8 miles Monitoring patterns caused by earthquakes and human made explosions Heavy inner core 3 other concentric layers

7 The Inner and Outer Cores Inner core solid and very dense Outer core of molten rock Both made of Iron/Nickel or Iron/Silicate 15% of the Earth s volume Magnetic field generated by the outer core Moves over time Reverses over long time

8 The Mantle Extends downward approximately 1800 miles 84% of the volume of the Earth Upper zone of thin, hot rock Middle zone of rocks so hard they easily deform Lower zone of rigid rocks

9 The Crust Outermost shell Mixture of rock types Thicker under the continents Less than 1% of the earth s volume Moho - tiny layer between the crust and the mantle

10 Isostatic Adjustment of the Crust The world we see is temporary Operates very slowly Internal processes build up landforms Vulcanism, folding, faulting, crustal rearrangement External processes Weathering, Mass wasting, Erosion

minerals Must be solid Naturally found in nature Be inorganic Must had a

11 The Composition of the Earth Minerals are chemical compounds that are found naturally in the Earth s crust About 100 Building blocks of rocks Rules for minerals Must be solid Naturally found in nature Be inorganic Must had a specific chemical composition Arranged in a regular pattern to form solid crystal

12 Rocks Composed of mineral material Sometimes one type, usually several types Solid rock at the surface is called an outcrop Buried layer is called bedrock Broken rock is called regolith

Igneous Rock Fiery inception Formed by the cooling and solidification of molten rock Variety of textures and colors Intrusive Cool and solidify

13 Igneous Rock Fiery inception Formed by the cooling and solidification of molten rock Variety of textures and colors Intrusive Cool and solidify below the surface then pushed up and uncovered Thousands of years Granite - Sierra Nevada Mountains Extrusive Form on surface Matter of hours Basalt

long period of time build up to incredible

15 Sedimentary Rocks External processes on rocks cause them to disintegrate Transported and deposited Over long period of time build up to incredible thicknesses because of pressure Forms distinct layers called strata

earth Common to find near intrusive igneous

17 Metamorphic Rock Sedimentary or igneous rocks that have been changed by heat and/or pressure Minerals recrystallize and rearrange Occurs below the surface of the earth Common to find near intrusive igneous rocks Some rocks changes are predictable Limestone! marble

18 The Rock Cycle 18

Rocks and the Rock Cycle. Banded Iron Formation

Rocks and the Rock Cycle. Banded Iron Formation Rocks and the Rock Cycle Banded Iron Formation Rocks Big rocks into pebbles, Pebbles into sand. I really hold a million, million Rocks here in my hand. Florence Parry Heide How do rocks change? How are