GEOG 1114 1st Edition Lecture 30 Outline of Last Lecture Karst topography continued Features continued Sinkholes Underground streams Hydrothermal features Outline of Current Lecture Review of chapters 13 15 Current Lecture Lecture 12 Ch 13 Introduction to Landforms Concepts and terms involved in understanding the Earth s Structure and composition Structure of the Earth understanding of the Earth s structure based in minute fraction of total depth less than 8 miles Crust outermost shell depth of 5 km below the ocean to near 20 km below land Less then 1 of the Earth s volume 04 of Earth s mass Moho Layer base of crust significant change in mineral Mantle Expands to depth of 2900 km 1800 miles largest of four shells Makes up 84 of total volume 67 of total mass These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Lithosphere top of moho layer hard ridged layer includes the crust Asthenosphere to about 200 miles hot tar like rocks pliable Mesosphere lower mantle Outer Core Molten magma extends to depth of 5000 km Inner Core Dense mass with a radius of about 1450 km Primarily made of iron nickel of iron silicate Magnetic field of Earth controlled by the outer core Magnetic poles not the same as the axial poles Major rock types Igneous Rock formed by the solidification of molten material called magma Formed by the solidification of molten materials magma Lava molten rock when it flows into Earth s surface Intrusive Igneous Rocks plutonic Rocks cool beneath earth s surface Surrounding rocks insulate the magma intrusion cools slowly Individual minerals in a plutonic rock can grow to large size Granite Gabbro Extrusive Igneous Rocks volcanic Form on Earth s surface when magma forces its way to surface Cools rapidly causing a glassy and or fine grained rock surface Outcrop rock at surface Basalt and Obsidian Basalt erodes more quickly then granite Igneous rocks particularly granite form about 80 of the earth s crust continents and oceans But sedimentary rocks often cover them They become important to landform development if exposed via uplift or erosion Sedimentary Rocks Rock formed of sediment that is consolidated by the combination of pressure and cementation Most widespread rock type of the land surface Consist of small particles of rock debris or organic material that were deposited by water wind or ice as sediments and were later consolidated by the combination of pressure and cementation This cementing takes place when sediments are laid down buried and compacted into horizontal layers called strata Although originally deposited and formed in horizontal layers the strata may later be uplifted tilted and deformed by pressures within the Earth There are many types distinguished on the basis of grain size How they were formed mechanically chemically or organically Strata Horizontal layers of sedimentary rock sometimes tilted Conglomerates compacted gravel formed mechanically cemented under pressure Sandstone compacted sandstone formed mechanically Limestone chemically accumulated rock composed of calcium carbonate coral and sea animals Shale cemented clay and silt formed mechanically Coal organically accumulated compacted skeletal remains of organisms Metamorphic Rocks Rock that was originally something else but has been drastically changed by massive forces of heat and or pressure working on if from within the Earth Causing a cooking of rocks Rearranges the crystal structure f the original rock Denser and less porous than its sedimentary or igneous parent Very resistant to weathering erosion Types include Slate derived from shale Schist derived from shale basalt Gneiss derived from granite Quartzite derived from sandstone Marble derived from limestone Landform structure and relief Topography surface configuration of Earth Landform Individual topographic feature of any size Geomorphology Study of landforms Relief Difference in elevation between highest and lowest points Structure nature arrangements and orientation of landforms slope 2 opposing forces of landform development Internal External Internal Surface disturbance produced by the earth s internal thermal energy Earth s internal heat generates extremely strong processes that result in crustal movements They are generally constructive uplifting building forces that tend to increase the relief of the land surface They include Crustal rearrangements earth s crust is plastic Plate Tectonics theory of lithospheric plate movements Volcanism movement of magma from interior of earth to surface Diastrophism compressional stresses of all the above These increase the relief of the land s surface External Molding of peaks slopes valleys and plains by the work of gravity water wind and ice Denudation Overall effect of external forces which level and lower the Continental surface Accomplished by Weathering Breaking up of rock in small components physical and chemical Mass wasting downslope movement of broken material due to gravity rock fall rock slide Erosion extensive and distinct removal of fragmented rock Six Factors of Landform Development Tectonic Activity Intensity of crustal motions produced by earth s internal energy Geologic Structure Nature and arrangements of material Denudation removal and deposition of rock material via weathering and erosion Climate Temp PPTN humidity and wind all effect rates of erosion deposition weathering and types of drainage Biota Vegetation soils organisms Humans all can influence rates and type of landform development Time Vastness magnitude Earth 4 6 billion years old Processes are very slow Dinosaurs 160 million years Results are high magnitudes Lecture 13 Ch 14 Internal Process Theory of Plate Tectonics how new crust is formed how crust is consumed Theory of crustal rearrangement based on the moment of continent sized lithospheric plates The Breakup of Pangaea Super Continent made of up existing continents put together like a jigsaw puzzle once existed around 300 million years ago About 200 million years ago internal forces of the earth became so great that the continents began drifting apart Evidence includes similar geologic features on coasts of different continents sea floor spreading Continents fit together Glaciate continents reconstructed made sense Rejected by many at the time But accepted today Driving Force Slowly moving convection of heated material within the mantle Sea Floor Spreading New