SLIDE 1 The Earth’s Surface
Natural Science II – ERTH 1040
SLIDE 2 Earth’s Surface
Keep in mind the major (and fundamental) sources of energy available to the surface of the Earth.
- Heat transfer from the interior – which
discussed in the previous lectures
- Heat transfer from the Sun
Radiation transfer from the surface of this star. There is only one other periodic source of energy external to the Earth: meteorite impacts
SLIDE 3
Earth’s Surface
Heat redistribution from the Earth’s interior means: Volcanic eruptions Crustal uplift These build mountains (and lowlands) This leads to potentials in gravity (potential energy that may change into kinetic energy). Simply: stuff will move downhill
SLIDE 4 Earth’s Surface As we’ll see, the distribution of solar across the Earth’s surface (recall direct sunlight falls only between the tropics) drives the evaporation and precipitation of water.
places is elevated to high places
downhill*
materials
*Most movement is underground
SLIDE 5
Earth’s Surface
SLIDE 6 Earth’s Surface
Changes in deposition produces layers of sediments. Erosion exposes the layers and permits easy direct
Sequential layering – newer sediments deposited on older.
SLIDE 7
Original horizontality
Q: where are the oldest rocks in a sequence of layered sediments?
SLIDE 8 Earth’s Surface
- Flat lying sediments are found forming in large
packages today - gulf coast basin.
- Smaller packages can be found in lakes, on river
floodplains, adjacent to mountains.
- The result of gravitationally driven erosion, transport,
and deposition.
- But what causes the gravity to be a force of
deposition?
SLIDE 9
Earth’s Surface Compression
Deviatoric Stress
Extension Shear
SLIDE 10
Earth’s Surface
Strain
Q: What’s the difference between stress and strain?
SLIDE 11 Earth’s Surface
Brittle - faulting
Extensional (Normal) Compressional (Reverse) Parallel to stress (Strike slip
SLIDE 12
Earth’s Surface An example from Big Bend N.P. Boquillas Cañon, view to Mexico from Texas across Rio Grande Compressional or extensional?
SLIDE 13
Earth’s Surface Graben Horst
SLIDE 14 20-405 Figure 20.17
Fault block mountains
SLIDE 15
Inclined Strata
An example from Twin Mountains, near Canyon City, CO
SLIDE 16
Earth’s Surface
Rotated half grabens
SLIDE 17 Earth’s Surface
Series of N-S fault blocks make up the mountains of the Basin & Range.
SLIDE 18
Earth’s Surface Siccar Point, Scotland Devonian Silurian
SLIDE 19 Angular unconformity
Inclined strata below (Arbuckle Group, Cambro-Ordovician) is eroded and covered by stream channel strata (Collings Ranch Conglomerate, Pennsylvanian). Represents ocean deposition, compression, extension, and stream deposition. Arbuckle Mountains, OK.
SLIDE 20
Ductile – folding
All compressional
Anticline Syncline Q: Why no extensional folding? What does extension do to ductile materials?
SLIDE 21
Earth’s Surface
Thrust fault – low angle reverse
Anticline and fault – brittle deformation is localized to the fault, ductile elsewhere.
SLIDE 22 Earth’s Surface
Arbuckle Mountains, OK
SLIDE 23 Earth’s Surface
Arbuckle Mountains, OK Rattlesnake Mountain, WY Glastonbury Anticline, CT
SLIDE 24 Earth’s Surface
Ouachita Mountains, Oklahoma
SLIDE 25 Earth’s Surface
20-404 Figure 20.16
Dome
The Adirondacks are a prime example of doming. Note now
- range (Ordovician) and light blue
(Cambrian) colors wrap around the pink, dark blue, and stippled areas (1.2Ga rocks).
SLIDE 26
Earth’s Surface
Asymmetric folding
SLIDE 27
Earth’s Surface
Asymmetric folding
SLIDE 28
Earth’s Surface
SLIDE 29
Earth’s Surface
SLIDE 30
Earth’s Surface
Earthquake
The ground motion associated with energy release during brittle deformation. Breaking transfers energy through surrounding material by moving it (seismic waves)
SLIDE 31 Earth’s Surface
20-401 Figure 20.12
elastic rebound theory
SLIDE 32
Earth’s Surface
Fault-related earthquake
Q: What is the difference between the epicenter and the focus?
SLIDE 33 20-403
locating earthquakes
Q: How do the two different types of waves differ from each
Figure 20.14
SLIDE 34
Earth’s Surface Q: What is the difference in ground motion between a magnitude 5 quake and a magnitude 6 quake?
SLIDE 35 Earth’s Surface
Richter TNT for Seismic Example Magnitude Energy Yield (approximate)
Breaking a rock on a lab table 1.0 30 pounds Large Blast at a Construction Site 1.5 320 pounds 2.0 1 ton Large Quarry or Mine Blast 2.5 4.6 tons 3.0 29 tons 3.5 73 tons 4.0 1,000 tons Small Nuclear Weapon 4.5 5,100 tons Average Tornado (total energy) 5.0 32,000 tons 5.5 80,000 tons Little Skull Mtn., NV Quake, 1992 6.0 1 million tons Double Spring Flat, NV Quake, 1994 6.5 5 million tons Northridge, CA Quake, 1994 7.0 32 million tons Hyogo-Ken Nanbu, Japan Quake, 1995; Largest Thermonuclear Weapon 7.5 160 million tons Landers, CA Quake, 1992 8.0 1 billion tons San Francisco, CA Quake, 1906 8.5 5 billion tons Anchorage, AK Quake, 1964 9.0 32 billion tons Chilean Quake, 1960 10.0 1 trillion tons (San-Andreas type fault circling Earth) 12.0 160 trillion tons (Fault Earth in half through center, OR Earth's daily receipt of solar energy)
SLIDE 36 Earth’s Surface Trinitrotoluene (TNT) Amounts of TNT are used as units of energy, based
- n a specific combustion energy of TNT of
4.184 MJ/kg = 1 calorie per milligram = 1.9 MJ per pound But…it’s not just the energy but the rate at which it’s delivered (power).
The Earth receives 6.08 E 17 MJ of energy from the sun but over a day (6.08 E 17 MJ / 8.6 E 4 s) 7.037 E 12 MW
And…it’s also the area on which its applied
Earth = 4re
2 = 5.10 E 8 km2 ) The Earth receives 1.38 E 4
MW/km2 of sunlight
SLIDE 37
Earth’s Surface
SLIDE 38
Earth’s Surface
NBC miniseries “10.5”
20 million viewers tuned in to watch a story based on a west- coast destroying earthquake Earthquake magnitudes are a function of the length and depth of the fault A 10.5 could only occur on a fault that encircles the globe more than once. Good new for bad science - a sequel has been filmed.
SLIDE 39
Earth’s Surface In absence of a seismometer, the intensity of an earthquake may be approximated using the modified Mercalli Scale Likewise, you can compare the type of damage done knowing the Richter Scale.
SLIDE 40 Earth’s Surface
The 1964 Good Friday Earthquake - Valdez, Alaska - largest historical quake in the U.S.
house
SLIDE 41
Earth’s Surface
SLIDE 42 Earth’s Surface The earthquake produced a landslide and a tsunami
Locomotive engine
Local land surfaces were noticeably uplifted
SLIDE 43
Earth’s Surface The tsunami was the second to hit the pacific in 4 years
SLIDE 44 Earth’s Surface
Volcanoes
Where partial melts of the Earth’s Interior reach the surface.
- Partial melts – magmas (mostly liquid with
some solid)
- These are hotter than surroundings – lose
heat and solidify
- These originate at depth – depressurize as
they ascend Q: What determines the nature of a volcanic eruption? How do these factors influence the morphology of a volcanic structure?
SLIDE 45
Earth’s Surface
The shape given to volcanic edifices is due to its eruptive style. It’s eruptive style is due to magma: Composition – including dissolved gasses
Low Si – more fluid High volatiles – more explosive
Supply rate – material from the Earth’s interior
Fast – frequent eruptions from same vent Slow – vents solidify, more explosive
The nature of an eruption is a function of the pressure of the magma.
SLIDE 46 Kilauea, Hawaii
March, 1996
Q: What are some common volatile components in a magma?
SLIDE 47 Earth’s Surface
shield volcano
Generally low Si Low volatile High rate
Hawaii: Hot asthenospheric mantle, below provides hot material that intrudes lithosphere and melts below oceanic crust.
SLIDE 48 Q: What tectonic feature produces volcanism in Hawaii?
Mauna Kea, Hawaii
Shield Cinder Cones
SLIDE 49 Q: What are the names given to these two types of lava?
Pu’u Hulu
Mauna Loa, Hawaii
Pahoehoe
SLIDE 50 Kalapana Gardens
Kilauea, Hawaii
SLIDE 51
Earth’s Surface
Fissure
SLIDE 52
Earth’s Surface
Cinder Cone
Low Si High volatile high rate
SLIDE 53 Summit Cone, Mauna Kea
Mauna Loa
Mauna Kea, HI
SLIDE 54 Pu’u O’o cone
Q: What does this lava lake signify in terms of volatiles?
SLIDE 55 Composite volcano
Mixed but generally Higher Si High volatile Low rate Composite volcanoes build up
- ver time from localized vents.
SLIDE 56
Earth’s Surface
SLIDE 57 Q: What tectonic feature produces volcanism in the Cascades?
Mount Saint Helens: pre 1980
Mount Saint Helens is an example of a composite stratocone - the locus of volcanism for hundreds of thousands
SLIDE 58 Earth’s Surface
Mount Saint Helens: March, 1980
In 1980, the mountain began to erupt small plumes of ash from an area near the summit. The first eruption in the conterminous US since that
California) in 1914.
SLIDE 59 Mount Saint Helens: May 18, 1980 0832
The north side of the mountain swelled during April and early May. It failed and slid away on May 18 releasing the gasses and magma in a cataclysmic explosion.
SLIDE 60 Mount Saint Helens: May 18, 1980
The release of heat melted the glaciers. Gas propelled ash into the upper troposphere.
SLIDE 61 Wyerhouser Logging Trucks Mount Saint Helens
Q: Is partially melted rock the only product of an eruption?
Meltwater, fallen trees, and ash choked the streams, destroying adjacent lands.
SLIDE 62 The eruption removed the top 1,800 feet of the mountain. View from the north
SLIDE 63 Earth’s Surface
Portland, OR
Several smaller eruptions continued through 1980. This included two that sent ash southward over the city
SLIDE 64 Q: What is a volcanic dome?
View from South Rim, June 1991
SLIDE 65 Earth’s Surface
Dome on Soufriere Hills Volcano Montserrat
SLIDE 66 Soufriere Hills Volcano Montserrat Soufriere Hills Volcano Montserrat
Q: How might volcanoes contribute to continental growth?
SLIDE 67
Earth’s Surface
Caldera
Moderate – high Si High volatile Low rate
SLIDE 68 Crater Lake, Oregon
SLIDE 69
Q: How do volcanoes impact climate?
SLIDE 70
Earth’s Surface
Earth’s surface is dynamic
Advantages: transfer of abundant energy Rivers (from mountains) to Hydrothermal Life utilizes the energy in these systems - not just in an electrical generation sense! Disadvantages: transfer of abundant energy Volcanoes, earthquakes, and floods Produce enough energy to displace matter and wreck habitats
SLIDE 71 Earth’s Surface Q: Which is the most efficient energy transfer mechanism?
- Asteroid or comet collision
- Loss of magnetic field
- Large earthquake
- Catastrophic eruption
SLIDE 72
Earth’s Surface
