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Click on a week for the lecture summaries:
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Please read appropriate sections of the textbook and lab manual prior to class
(and lab) and take good notes. After class, reread the text and augment your
notes, then see me if you are having difficulty; my office is in Bentley 332.
Please do not fall behind or miss pieces of the puzzle.
Consider purchasing the textbook by Marshak and Rauber (2017) online at BookFinder4You or BooksPrice, or purchase it at the JSC Bookstore. There is no lab manual this semester. A copy of the textbook is on reserve in the Willey Library.
See the class syllabus for required readings and class policies.
The first presentation for this course will be held on Tuesday, 22 January 2019 and start at 1:00 p.m.; we will meet in Bentley 206. Read pages xxi-xxvii, and pages 3-9, before class on Tuesday.
The first lab will be held on Wednesday, 23 January 2019 in Bentley 101, starting at 1:00 p.m; we will meet in Bentley 101. Please come to lab prepared to work with topographic maps.
Today's big idea: The higher cognitive domains of intellectual development allow us to apply the methods of science in order to explain how nature works. Scientists question everything and are always open to new observations, which in turn, allows us to improve our understanding of the fundamental laws of nature.
An overview of the course was presented during the first class meeting. Click here to learn about what geologists do and the types of careers that are available in the geosciences.
Put down your electronics; read a recent article by Mark Zuckerberg (founder of Facebook) entitled "The web has stolen my creativity". Read the Dec 2010 paper about the relationship between brain tumors and cell phone use (published in the Journal of Computer Assisted Tomography, volume 34). Take a look at the SAR rating for your cell phone, and if it is high, then try and keep it at least one inch away from your head (or get a safer phone). See the SAR site of the Federal Communications Commission.
The lecture began with a discussion of Bloom's Taxonomy of Educational Objectives (knowledge, comprehension, application, analysis, synthesis, and evaluation) and Dr. Andersen's modifications (remember, understand, apply, analyze, evaluate, create).
The nature of science, and the distinction between observations, hypotheses, theories, and laws were introduced. Yogi Berra said: "You can observe a lot just by watching." Watch a seven-minute video about facts, hypotheses, theories and laws by Joe Hanson, Ph.D., or check out his website.
As scientists, we recognize patterns in nature when we observe phenomenon over and over again. Eventually, we generalize our experiences and summarize what we have learned. An assumption, subject to verification or proof, is a conjecture that accounts for a set of observations and can be used as a basis for further investigation. This is a hypothesis. It is, in fact, a proposal. It is a tentative explanation for an observation, phenomenon, or scientific problem that can be tested by further investigation. We consider these types of ideas to be hypotheses. Scientific hypotheses must be posed in a form that allows them to be rejected.Theories, on the other hand, are well tested and widely accepted hypothesis. Theories model a restricted part of the universe. They are models with a set of rules. A good theory has two properties: 1) they describe a large class of observations with few arbitrary elements, and 2) they make definite predictions about the results of future observations.
For all health and safety issues it is often wise
to apply the Precautionary Principle. The Wingspread
Conference defined the Precautionary
Principle as follows: "When an activity raises threats of harm to
human health or the environment, precautionary measures should be
taken even if some cause and effect relationships are not fully
PowerPoint slides: Science
PowerPoint slides: Topography
Topographic maps depict the landforms by use of contour lines. Contour lines are lines of equal elevation; the contour interval specifies the difference in elevation between two adjacent contour lines. Contour lines specify the elevation above mean high tide. Index contour lines are bold and labeled (every fifth contour line on the map). Features on topographic maps are represented by a wide variety of symbols.
Bar and ratio scales are used to convey distances these scales are the horizontal scales of the map. Ratio scales are unitless (or have the same units on both sides) and are always expressed as 1:X (where X is any number). A map scale of 1:24,000 means that one unit on the map (any unit) represents 24,000 of those same units on the ground.
Cross-sections, also known as topographic profiles, show the relief by providing a side-on profile (or cross sectional view) of an area. Click here to learn how to make cross-sections.
Learn about UTM grids at the USGS site or at a site maintained by MapTools. USGS topographic maps are available for free download.
Topozone.com supplies topographic maps, for free, for most of the USA; or visit the USGS Store for topographic maps (or here for the Johnson Quad); also see historic topographic maps of Vermont. See An Introduction To Topographic Maps Tutorial from the Geospatial Training And Analysis Cooperative, Idaho State University. CalTopo.com provides a fantastic set of maps for free.
Vertical exaggeration (VE) is a number that represents how many times the vertical scale is amplified (larger) with respect to the horizontal scale. The horizontal scale is fixed for any given map, it does not change. A cross section with no vertical exaggeration has a horizontal scale (map scale) equal to the vertical scale (of the cross section). Use the horizontal scale as the basis for determining the vertical scale when constructing a topographic cross section. Scaling along the vertical axis of the cross-section determines the vertical exaggeration.
- Submit the topographic map created in lab.
- Draw two cross-sections, one without vertical exaggeration (VE) and a second cross-section with a VE equal to 3. Be sure to clearly label all cross sections (specify the vertical exaggeration for each cross section, put the units on the vertical axis, and compass directions of the traverse).
- Calculate the ratio scale for your map. Be sure to clearly write out the equations and show all of your work.
Please submit the map drawn in class and the cross-section handout. Answer Question 3 on the back of the cross-section handout, be sure to show all mathematical work, and write legibly. You do not have to type up this assignment because there are few words with a little bit of math.
Today's big idea: Redshifted spectra indicate the universe is expanding. The expansion rates are consistent with our understanding of how the universe evolved since the beginning of time, the time of the Big Bang. The results of experiments using the Large Hadron Collider have provided more evidence in support of the Standard Model. This model describes the fundamental forces, fundamental particles, and laws of nature that describe our understanding of the evolution of the universe.
The nearest galaxy is the Andromeda Galaxy that is 2.5 million light years away from Earth.
The nearest star is Proxima Centauri (part of star cluster Alpha Centauri) that is 4.22 light years away from Earth. Proxima b is an Earth-like planet orbiting this star.
The electromagnetic spectrum (EM) incorporates the full range of frequencies from the very long radio waves to the very short gamma rays; visible light is also part of the EM spectrum. All waves in the EM move at the speed of light. Light travels at 299,792,458 meters per second (that corresponds to 670,616,629 miles per hour). The distance that light travels in one year, about 5.9 trillion miles, is regarded as a light year.
Some videos and images of relevance:
Several telescopes are being built to allow us to see further and more clearly:
The galaxies seem to be surrounded by dark matter and the center of many galaxies are presumed to be black holes. The universe is composed of 4.6% ordinary (normal) matter, 24.0% dark matter, and 71.4% dark energy (the cosmic pie). WIMPs and MACHOs may be the fundamental particles that provides the mass not observed, but inferred, in the universe. WIMPs (about 100 GeV) have the right thermal abundance to account for dark matter.
Dark energy may be the force that beats out gravity and is causing the universe to expand at an ever-increasing pace. Dark matter does not emit or reflect light, so it can't be seen. We infer the existence of dark matter through its gravitational effect on normal matter. It may be comprised of various types of exotic particles with names such as neutralinos, axions and gravitinos. Dark matter may account for the formation of the first stars (normal matter). Recent reports suggest that the atoms that make up stars, planets, air, and life account for only a small fraction of what must exist. Either our understanding of gravity is wrong, or an additional source of gravity is required to stop galaxies from flying apart. It is theorized that dark matter could be this additional source of gravity. Watch Professor Lisa Randall describe dark matter.
The Big Bang theory attempts to explain the early evolution of the universe that we believe began about 13.82 Ga; 1 Ga = billion years. Click here for a series of essays on cosmological evolution. In March 2014, Prof John Kovac of the Harvard-Smithsonian Center for Astrophysics, new evidence to support a Big Bang Theory.
The European Center for Nuclear Research (CERN) attempted to start experiments on 10 Sep 2008 using the Large Hadron Collider (LHC). Watch a video introduction of the LHC. The $10,000,000,000 LHC at CERN is back online after a 14-month repair to some of the magnets. Click here for a rap song regarding the LHC. The LHC will model situations associated with the Big Bang, dark matter, dark energy, and the evolution of galaxies. Click here for a general introduction to CERN and the LHC (text and videos). Fantastic pictures of the LHC are published by the Boston Globe.
Red-shifted spectra indicate the rates at which stars (and galaxies) are moving away from other stars (and galaxies). The farther the spectral lines are shifted into the red (i.e. longer wavelengths), the faster the stars are receding. Distances to stars are measured by stellar parallax.
Some links related to the formation of the universe:
Stephen Hawking is a pre-eminent astrophysicist at Gonville and Caius College at the University of Cambridge. He is the former Lucasian professor of theoretical physics and mathematics. Learn more about Stephen Hawking by accessing some of the following links:
Thursday: no class...
PowerPoint slides: Galaxies
PowerPoint slides: Redshift
PowerPoint slides: Latitude and longitude
Read about latitude and longitude, the Universal Transmercator System, and the International Date Line.
Coordinate systems (latitude and longitude or the Universal Trans Mercator system) can be used to locate a place on Earth. Latitude (0 - 90º) measures the angular distance (N or S) from the equator; longitude (0 - 180º) measures the angular distance (E or W) from the Prime Meridian. One degree (º) of arc is equivalent to 60 minutes (') of arc; 1 minute of arc is equivalent to 60 seconds (") of arc. Furthermore, 1º of latitude (not longitude) is equivalent to 111 km of distance (60 nautical miles or 69 statute miles).
The Universal Trans Mercator system is based on meters (not degrees). The seven digit values report northings an eastings. Each unit is one meter in length. The UTM system is designed to be used for latitudes between 80°S and 84°N; it does not include the polar regions. The origin of each zone is the equator and its central meridian. In the Southern hemisphere the 0 value is referenced to the latitude which is 10,000,000 meters south of the equator. The value given to the central meridian of each zone is a false easting of 500,000.
The solar system comprises the sun, planets, asteroids, moons (and other rocks and gasses that encircle some planets) and some comets. High Resolution Imaging Science Experiment (HiRISE) camera mounted on NASA's Mars Reconnaissance Orbiter has produced amazing photographs of Mars.
On 24 August 2006, the International Astronomical Union redefined the term planet our solar system now has only eight planets; the trans-neptunian bodies are not planets Pluto is no longer regarded as a planet, but as a dwarf planet. In July 2015 the New Horizons spacecraft should be passing by the Pluto system (that includes six moons); the craft will have travelled about 3 billion miles from Earth – it takes 4 hours and 26 minutes for electromagnetic waves to travel that distance!See a video of the Space Shuttle conducting a backflip and other images of shuttle launch preparation (a 3 Mb PowerPoint file). The Space Shuttle will be retired and DIRECT or SpaceX may be the replacement space vehicle. Have you ever wondered how astronauts on the International Space Station (ISS) go to the bathroom without a gravity assist (this link too)? View a video about life inside the ISS. The first espresso machine was just delivered to the ISS. Watch a video and learn if graviception prevents dizziness.
In September 2002, a large object in the Kupier Belt was identified and given the name Quaoar. Some considered this object to be the tenth planet in the solar system. In March 2004, another planet-like body was discovered at the fringes of our solar system. The object is three times farther away from Earth than Pluto, making it the most distant known object in the solar system. At its most distant, Sedna is 130 billion kilometers (84 billion miles) from the Sun and larger than Quaoar. Until Sedna was detected, Quaoar was the largest known body beyond Pluto. Vesta and Ceres are the most massive objects in the asteroid belt. In June 2012, Vesta was reclassified as a protoplanet prior to that it was classified as an asteroid.
Some of the consistent observations of the solar system include:
The NASA Mars Science Laboratory with the Curiosity rover is on Mars. Curiosity's electrical power will be supplied by a U.S. Department of Energy radioisotope power generator that produces electricity from the heat of radioactive decay of 238-Plutonium. Watch an animation of Curiosity's landing.
There are planets that orbit other stars. Extrasolar planets exist the sun is not the only star that has orbiting planets; see the Extrasolar Planets Encyclopaedia. Astronomers recently identified a fifth planet in a solar system only 41 light years from Earth. We have now identified about 3976 extrasolar planets. In November 2008, NASA's Hubble Space Telescope took the first visible-light snapshot of a planet circling a star; the star is only 25 light years away!
There are about 1947 potentially hazardous asteroids (PHA) and comets that are continuously monitored. A PHA has a minimum orbit intersection distance of 0.05 astronomical units (AU); one AU is the distance between the Earth and the sun (149,000,000 km). See SpaceWeather.com for more information. Click here to view an animation of known objects close to Earth; click here to see more animations and associated descriptions. Look at the catalogue of Earth Impact Structures (190 sites have been identified) and look at terrestrial impact craters. Take a look at the Meteorite Catalogue Database from the Natural History Museum or calculate the effects of bolide impacts. The American Meteor Society observes, monitors, collects data on, studies, and reports all things related to meteors. Click here or here to plan for viewing the next meteor shower. Space junk (debris from older satellites) poses a major problem for satellites in orbit around Earth.
On 14 Feb 2012 a record setting asteroid, about 50 meters in diameter, came within 0.09 lunar distances of Earth. On the same day a 15-meter diameter meteorite burnt up in Earth's atmosphere (25 km) and blew out windows over a distance of several hundred miles. See numerous videos of this event here or here. Meteors of this size hit Earth, on average, every 1200 years, yet the Tunguska Event in 1908 was much larger. Monitor the space weather here.
NEOshield is a project to assess how we can protect Earth from Near Earth Objects (NEO) through use of kinetic impactors, gravity tractors, or blast deflection. There are over 10,000 NEOs and more are found each month. NEOs, in general, have orbits around 1.0 AU. A re-analysis of historical observations suggest Earth narrowly avoided an extinction event just over a hundred years ago. The Hayabusa spacecraft just returned samples from asteroid Itowaka. Keep an eye out for Apophis a very close approach to Earth on Friday, 13 April 2029 at 30,000 km; it may hit on 13 April 2036! Deep Space Industries hopes to mine asteroids and intends on sending prospecting satellites in 2015 (with larger spacecraft embarking on round trips later that year to collect and return material from asteroids). The Asteroid Deflection Research Center, at Iowa State University, has been studying a variety of ways to address the potential problems of asteroid impacts.
Comet ISON had a fantastic showing in November 2013. Europe's Rosetta spacecraft entered orbit around comet 67P/Churyumov-Gerasimenko and crash landed a probe on its surface in November 2014; click here for its travel path. Click here and here to read more about a comet that was more than eight times larger than Halley's Comet and just missed Earth.
Look at the Earth and moon viewer, or look at the current position of the sun, Earth, and Luna (Earth's moon).
Voyager 1 was launched in 1977. In late 2012 it reached the edge of the solar system and is now flying in interstellar space. This is the first and only craft that has travelled such a distance. It takes light about 17 hours to travel such a distance.
Today's big idea: Planets form by accretion of chemically similar particles created when a new star forms. The regular change in chemistry of the planets, with increasing distance from the sun, is related to temperature. The gas giant planets are found farther from the sun where the lower temperature allows gasses to condense (gasses burn off nearer to the sun). As chemically similar particles accrete to form a planet, the temperature of the early forming planet heats up to the melting temperature of iron and the result is the iron catastrophe and initiation of convection that accounts for a layered planet.
Protoplanets (young planets) formed by the accretion of nearby, homogeneous, material ejected by the newly formed star. Protoplanets of the asteroid belt, however, did not coalesce to become a planet. Protoplanets formed through the process of homogeneous cold accretion, that is, all the materials in a specific distance from the newly formed sun has the same composition (i.e. homogeneous). Accretion was accompanied by bombardment, gravitational compression, and radiogenic decay all of which resulted in a temperature increase of the early Earth. After 1 Ga (billion years) of heating associated with accretion, early Earth heated to the melting point of iron, which resulted in the iron catastrophe. The iron catastrophe is represented by denser material sinking toward the center and lighter material moving toward the surface of Earth. This initiated convection (that now drives plate motion) and differentiation (layering) of Earth.
Convection is the driving force behind plate movements and is thus responsible for most of the plate movements, earthquakes, and volcanoes that occur on Earth.
The common minerals (silicates) are made of the common elements in Earth's crust (O, Si, Al, Fe, Ca, Na, K, and Mg). These elements are common in the crust because of the differentiation (layering due to density differences) associated with the iron catastrophe.
Earth's interior can be modeled through seismic tomography. The deepest hole drilled was on Russia's Kola Peninsula. It took over 20 years to drill to a depth of 12,262 meters. A few years ago the deep sea drilling vessel, Chikyu, was commissioned to conduct deep drilling. The ships drill stem is 10,000 meters long! It wont beat the record depth of over 12,000 meters, but it can drill more quickly and recover cores.
Earth's early atmosphere and oceans were a result of the degassing of the planet. Over time the composition of the atmosphere changed (more oxygen-rich), thus allowing life to move from the oceans onto land and evolve to present-day conditions. Early life on this planet may have been seeded by comet impacts. The simple organic compound methane, and water, were found in the atmosphere of a hot (900ºC), Jupiter-sized planet orbiting a star (HD 189733b) some 63 light years away from Earth. This is the first time we have been able to detect an organic molecule on another planet!
PowerPoint slides: Solar system
PowerPoint slides: Atoms and minerals
In lab we explored the properties minerals and distinguished elements from minerals, and minerals from rocks. Atoms are defined by the number of protons in the nucleus, minerals are defined by the types atoms and structural arrangement of the atoms in the mineral, whereas, rocks are defined by the types of minerals and the textural arrangement of the minerals in the rock.
Today's big idea: The mass of an atom, and ultimately the density of all materials, is controlled by the total number of protons and neutrons in the nucleus of an atom. We name the atom by counting the number of protons, and we name the isotope of an atom by adding the number of neutrons to the number of protons. The size of the atom, and bonding atoms together, is primarily controlled by the electron cloud.
There are hundreds of subatomic particles; all subatomic particles are made of quarks. For simplicity, we are interested in only three subatomic particles: protons, neutrons, and electrons:
The atomic mass of an element represents a weighted average of all of the isotopes of that type of atom. For example, the average atomic mass of carbon, C, is 12.011 amu. Some isotopes of carbon have 5, 6, 7, or 8 neutrons (11C, 12C, 13C, or 14C respectively). Most isotopes of carbon have 6 neutrons and therefore the average atomic mass of carbon is about 12 amu (6 neutrons + 6 protons). See the table of nuclides produced by Brookhaven National Laboratories. Isotopes are atoms of the same type (same atomic number, i.e. same number of protons) but have varying atomic mass (i.e. varying numbers of neutrons). Some isotopes are stable and others are unstable (radioactive). There is no magic formula for determining which isotope of an atom is unstable; the stability of an isotope is governed by the weak nuclear force. Read more about isotopes from the US Geological Survey. Hydrogen has numerous isotopes: 1H (hydrogen), 2H (deuterium), and 3H (tritium); read about the sources and health effects of tritium. There are shortages of 99Mb (molybdenum) which are causing delays for certain medical tests (such as heart and kidney function tests and bone scans, including those looking for tumors).
A mol is equivalent to 6.022 x 1023 of similar atoms (known as Avogadro's Number). A mol of atoms is equal in weight (in grams) to the atomic mass of that element. In other words, it takes 6.022 x 1023 atoms to account for the mass of one mol of atoms of a specific isotope. The atomic mass of an atom depends on the density of the atom, and the density of the atom depends on the number of neutrons and protons in the nucleus of the atom. Read more about the structure of matter at the Nobel e-museum. Atomic scale images have been created by IBM, or listen to a song about the elements, or a song about quarks.
Neutrons and protons are found in the nucleus of an atom and define the atomic mass of that atom. Electrons are found around the nucleus in various orbitals, also known as energy levels (as described by the Schrödinger wave equation). Electrons fill the orbitals according to the Octet Rule and the Bohr Theory, which states that a maximum of eight electrons can occur in any orbital (except the first, which can hold only two electrons). The Bohr Theory is only somewhat applicable to atoms of low atomic number; it is a good model to demonstrate valence shell electrons and bonding. The number of electrons in the outermost orbital are the valence shell electrons. Valence shell electrons control bonding. The columns on the periodic table of the elements indicate the number of valence shell electrons.
Atoms bond with other atoms to make minerals.
Atoms seek to have a full valence shell of electrons (the Octet Rule)
and follow Pauling's Rules. Atoms fill their valence shells by
transferring (ionic bonds), sharing (covalent bonds), or borrowing
(metallic bonds) electrons from other atoms.
Minerals are uniquely defined by their chemical composition and crystal structure. This in turn governs mineral properties and mineral symmetry (for example, mirror planes or rotation axes). The regular, repetitive, crystal structure forms when atoms bond according the Octet Rule and Pauling's Rules. The repeating unit cell, the motif, contains all of the atoms (in the correct proportions) that are required to define the chemical formula of that mineral. Click here to see Snowflake Bentley's hexagonal snow crystals, or click here to make virtual snowflakes.
Mineral classes are defined by their anion molecule. A few examples include: the silicates (SiO4-4), carbonates (CO3-2), and chlorides (Cl-1). Click here to see one of the largest mineral databases on the Internet, click here for another database, or read about some of the largest minerals in the world that are found at the Naica Cave system.
Atoms bond together to make minerals; minerals come together to make rocks. Rocks look different from each other because they are made of different minerals and the minerals have different appearances (textures) in different rocks. The texture of a rock depends on how it was formed. The common igneous rocks (Bowen's Reaction Series) comprise the common minerals (silicates) that are made of the common elements (O, Si, Al, Fe, Ca, Na, K, and Mg) in Earth's crust (as a result of the iron catastrophe).
See the website for the Vermont
Geological Society to view common rocks of
the state of Vermont.
Outline the unit cell and write out the chemical formula for the geometric pattern distributed in class. Please note that if half of one atom is outside the unit cell, then the other half should be found on the other side of the unit cell and there will always be a whole number of atoms (no halves or quarters of atoms). The unit cell will be the smallest geometric shape whereby all lattice points have similar environments. Draw about ten adjacent unit cells on the handout.
PowerPoint slides: Isotopes
PowerPoints slides: Uniformitarianism
Handout: Relative dating
Steno's Principles of 1) Superposition, 2) Lateral Continuity, and 3) Original Horizontality were introduced. We discussed geological time, relative dating, Steno's Principles, cross-cutting relationships (folding, tilting, metamorphism, faults, intrusions), and unconformities (erosional surfaces).
View animations of relative dating and unconformities or faulting.
Work with Figure 12, p. 91, on the handout distributed in lab today. Use the geological processes discussed in lab (deposition; erosion or unconformity; intrusion: dike, sill, or batholith; lava flow; fault: normal or reverse; and deformation: folding or tilting), the name of the rock unit, and the identity (a letter) for each event. Be sure to type the response and put the oldest event on the bottom of the list.
Today's big idea: The weak nuclear force controls the mechanism and rate of decay of unstable isotopes. Unstable isotopes can be used for dating geological events, medical technology, nuclear energy, and nuclear weapons.
The US Naval Observatory is the official time keeper for the United States; also see the NIST Physics Laboratory for more information. Click here for the official US time. Click here for a copy of a geological time scale. for a geological time scale. Or see an interesting page about dates (and links to other calendar pages). Click here for a discussion of calendars or here for the justification for a lot of time-related events.
Easter can never occur before March 22 or later than April 25. The day that Easter is celebrated is governed by relative positions of Earth, sun and moon; click here for more information.
A positive leap second was introduced on midnight 30 December 2016. Leap seconds can be either positive or negative depending on the Earth's rotation. Since the first leap second in 1972, all leap seconds have been positive and there were 28 leap seconds in the 43 years to January 2019. This pattern reflects the general slowing trend of the Earth due to tidal braking.
In 2005, President Bush signed into law a new energy policy bill that extended Daylight Saving Time by four weeks (beginning in 2007):
The Mayan calendar does not predict the end of the world, it only marks the end of a calendar era. Read more about it from the BBC, Reuters, and NASA.
See the video "How Earth Moves" to learn about time and Earth's movements in space.
Humans have had such an Effect on Earth's systems that a new Era has been suggested: Anthropocene Era.
Nuclear chemistry allows us to date geological events by use of unstable isotopes. Isotopes can be identified by use of a mass spectrometer. Unstable isotopes generate radiation as the nucleus undergoes spontaneous decay. The weak nuclear force controls the rate and mechanism of the decay of the nucleus.
Common decay mechanisms include:
Half-life is the average amount of time required for one half of the original number of radioactive atoms (parent atoms) to decay to child (daughter) products. Unstable isotopes are used for absolute dating. Each isotope has a defined half life. After five half lives, only 1/32 of the parent isotope remains; this small amount is difficult to measure accurately so we choose an isotope that has a half life appropriate to the age of the feature of interest (for example, depositional age, age of crystallization, or age of metamorphism).
The Vermont Department of Health can also test your water for a large number of contaminants. A Gross Alpha test (section 4 RA) costs $45. Click for forms and ordering information; get the order form for all water tests (and costs); read the supplement associated with the order form.
Radon is an unstable isotope that occurs as a gas and forms from the decay of radium. Radon gas is a problem in many dwellings because radium may often be substituted for other elements that have two valence electrons. According to a report by the National Academy of Sciences, radon is estimated to cause between 15,000 and 22,000 lung cancer deaths per year. It is the second leading cause of lung cancer after smoking. Please read more about Radon found at the Vermont Health & The Environment website.
Read about a Russian spy who exposed Russian President Putin's ring of corruption and was subsequently poisoned by radioactive 210Po while in London. Or learn more about the "Radium Girls" who are still glowing in their coffins.
Gravity is a force of attraction; this force is always perpendicular to Earths surface and measured in gals. Earths gravitational attraction = 980.665 gals = 9.80655 m/s2 = 980.665 cm/s2. The pull of gravity varies on Earth because of: centrifugal force (Earth spins at 1669 km/h at the equator), latitude (polar radius: 6357 km, equatorial radius: 6378 km), near surface mass, and topography.
After corrections for centrifugal force, latitude, near surface mass, and topography are made, and a gravity anomaly still exists, it could be related to crustal areas seeking isostatic balance. Isostacy describes a mechanism where areas of Earths crust rise or subside until the mass of the topography is buoyantly supported (compensated) by the thickness of the crust that "floats" on denser mantle. Negative anomalies may occur over regions where the crust has not rebounded from the retreat of ice sheets, mountain roots, sedimentary basins, rift basins, subduction zones, mid-ocean ridges, or over salt domes. Positive may anomalies occur over ore bodies.
Launched on 17 March 2009, ESA's Gravity field and steady-state Ocean Circulation Explorer (GOCE) was developed to measure Earth's gravity field. GOCE will map global variations in the gravity field with extreme detail and accuracy.
Airy Hypothesis: an equilibrium of crustal blocks of the same density but of different size; thus the topographically higher mountains would be of the same density as other crustal bocks (but would have greater mass and deeper roots).
Pratt Hypothesis: an equilibrium of crustal blocks of varying density; the topographically higher mountains would be less dense than the topographically lower units and the depth of the crustal material would be everywhere the same.
PowerPoint slides: Gravity and isostacy
Handout: Relative dating
The specific gravity was determined for a variety of rocks and minerals that represent oceanic and continental lithosphere.
Write up the results according to the assignment handed out in class and be sure to follow the proper format for writing. This assignment is worth two lab grades.
|Na-rich plagioclase feldspar||NaAlSi3O8|
|Ca-rich plagioclase feldspar||CaAl2Si2O8|
The geothermal gradient measures the temperature change with depth below Earth's surface. The average geothermal gradient (GG) is approximately 30ºC/km. At divergent plate boundaries the GG is higher than the average, whereas at convergent plate boundaries the GG is lower than the average. The rocks that form along plate boundaries reflect the geothermal gradient and the composition of the source material. Low geothermal gradients are commonly associated with subduction zones; the rocks that form under these conditions reflect the conditions of low temperature, high pressure, and mafic (basaltic) composition.
Seismology is the study of Earth and earthquakes using seismic waves. An earthquake releases seismic energy in the form of seismic waves. L-waves are surface waves and are the slowest seismic waves; P-waves and S-waves are body waves. P-waves are compressional waves, travel almost twice as fast as S-waves, and pass through solids and liquids; S-waves are shear waves and therefore cannot pass through liquids.
The time difference between the arrival of the first P-wave and the arrival of the first S-wave is known as the S-P interval. This difference in arrival times increases with increasing distance from the focus. Triangulation can be used to locate the focus of a seismic event. Seismic tomography is used to describe Earth's internal structure. Through our understanding of seismic waves, we have been able to identify the many layers within Earth.
The elastic rebound theory suggests that rocks at the surface respond to stress in a brittle fashion. In contrast, rocks at depth respond in a ductile fashion. The temperature and pressure increase with increasing depth these elevated conditions of pressure and temperature favor ductile deformation. In fact, the average geothermal gradient is 30ºC/km and the average pressure gradient is 0.3 kb/km.
The Richter Magnitude Scale records the amplitude of the recorded seismic wave. An amplitude of 1 cm, at a distance of 100 km from the epicenter, is regarded as a Richter magnitude 4 seismic event. Each increase of one unit on the Richter scale corresponds to a ten-fold increase in the amplitude of the recorded seismic wave and a thirty-two-fold increase in the energy released by that event.
The Modified Mercalli Intensity Scale is a measure of what is felt on Earth's surface; it is based on a scale from I (1) to XII (12). The public is encouraged to report their observations to the USGS. The damage that results from a seismic event is based on the geology, distance to epicenter, depth of focus, and anthropogenic modifications to the land.
Learn about recent seismic activity from the USGS Earthquake Hazards Program or search the Significant Earthquake Database. Learn about some of the interesting, active research on the San Andreas fault system. See Earthscope for locations of seismometers in the US. Read about the history of destructive earthquakes in the Himalayan Mountains.
Seismicity is associated with ground motion. Poorly consolidated rocks lose their cohesive strength when subjected to the shaking associated with seismic waves and the rocks are unable to support any structures. This process is known as liquefaction. Tsunamis are large amplitude and long wavelength ocean waves initiated by the displacement of water associated with an earthquake.
See the United States Geological Survey report of seismicity in Vermont or a brief discussion of the 20 April 2002 event felt throughout Vermont. Click here for recent (the past week) seismic activity in Vermont.
Watch the sequence of seismic events that lead up to the 2011 Tohoku earthquake, also known as Great East Japan Earthquake, of Friday, 11 March 2011.
Earthquakes cannot be predicted, however, some inconsistent precursors have been identified (for example, unusual animal behavior, gas emissions, precursor seismic events, change in groundwater levels, change in resistivity, and earthquake lights with associated brontides).
PowerPoint slides: Seismicity
Handout: Earthquake Hazards
Figure 7, p. 108 was submitted – the location of the epicenter was clear, accurate, precise and defined by latitude and longitude. The time of the earthquake, and a description of how the time was determined, was also required.
Polar lights: The northern lights (Aurora Borealis) have the same origins as the southern lights (Aurora Australis). The solar winds, associated with solar flares and coronal mass ejections, produce solar protons that interact with Earth's magnetic field. This interaction produces bands of light that are oriented parallel to the lines of magnetic force (which are directed toward the north and south magnetic poles of Earth). The colors of the polar lights are related to atmospheric chemistry: nitrogen produces red bands of light, whereas oxygen produces green and white bands of light.
Earth's magnetic field represents yet another aspect of electromagnetism. The electromagnetic spectrum is continuous with frequencies ranging from zero to about 1023 Hz. The magnetic field is created by a flow of electrons because a charged particle moving with uniform motion creates a magnetic field around itself. Magnetic field strength: 0.60 gauss at the magnetic poles and 0.25 gauss at the magnetic equator. A typical household magnet has a field strength of 100 gauss.
How can a magnetic field exist in Earth's core when the temperature is too hot for a bar magnet to maintain a magnetic field? The answer lies in the interaction between Earth's inner and outer cores. The source of Earth's magnetic field results from the interaction of the inner core and the partially ionized outer core. Convection in the outer core distorts the magnetic field and causes it to wander.
Navigation: The needle on a compass points toward magnetic north. Magnetic north is not always coincident with true north (the geographic north pole). The angular difference between true north and magnetic north is called declination. The declination must be known in order for a compass to work properly. Magnetic north moves about 10 to 40 meters per day (27 to 109 km per year), and therefore the declination is always changing, this is known as secular variation. Furthermore, each location on Earth has a specific declination. See the US Geological Survey's National Geomagnetism Program for more information. Compute the values of the magnetic field in your area through the NOAA site. The declination in Johnson, VT, on 6 March 2019 is 14° 24' W changing by 0° 6' E per year.
Paleolatitude: The lines of magnetic force are perpendicular to Earth's surface at the polar regions and parallel to Earth's surface in the equatorial regions – this is only true when the declination is zero, otherwise we must consider the north magnetic pole and the magnetic equator. If the movement of the north magnetic pole is averaged over 10,000 years then it coincides with the geographic North Pole. When molten material cools beneath the Curie point (about 450ºC), magnetic domains form, and the ambient magnetic field is locked into the rock; this is known as thermal remnant magnetism (TRM). Iron-rich cements associated with sedimentary rocks also tend to align with the ambient magnetic field during lithification; this is known as depositional remnant magnetism (DRM). TRM and DRM are used to determine the latitude where the rocks formed.
Sea-floor spreading: Reversals of Earth's magnetic field are recorded in ocean floor when the rocks form (as they cool past their Curie Point). Reversals occur at intervals ranging from 10,000 years to more than 25,000,000 years. The magnetic field strength goes to zero during a reversal. We cannot predict when the next reversal will occur.
Stern (2001) states: "In nature, magnetic fields are produced in the rarefied gas of space, in the glowing heat of sunspots and in the molten core of the Earth. Such magnetism must be produced by electric currents, but finding how those currents are produced remains a major challenge."
Glatzmaier (1995) states: "... the temperature of the core is too high to sustain permanent magnetism... These observations argue for a mechanism within the Earth's interior that continually generates the geomagnetic field. It has long been speculated that this mechanism is a convective dynamo operating in the Earth's fluid outer core, which surrounds its solid inner core, both being mainly composed of iron. The solid inner core is roughly the size of the moon but at the temperature of the surface of the sun. The convection in the fluid outer core is thought to be driven by both thermal and compositional buoyancy sources at the inner core boundary that are produced as the Earth slowly cools and iron in the iron-rich fluid alloy solidifies onto the inner core giving off latent heat and the light constituent of the alloy. These buoyancy forces cause fluid to rise and the Coriolis forces, due to the Earth's rotation, cause the fluid flows to be helical. Presumably this fluid motion twists and shears magnetic field, generating new magnetic field to replace that which diffuses away."
PowerPoint slides: Magnetism
Handout: Ocean Floor
Please submit your answers to Questions 12-26 from the lab manual (starting on page p. 115).
Heat from Earth's interior drives mantle convection, volcanism, seismicity, and plate movements. The theory of plate tectonics allows us to better understand how Earth has been modified through tectonic forces. See Scotese's site for plate reconstruction animations. The central region of a large continental landmass is old and commonly referred to as a continental cratonic region. Sediment is deposited along the edges of the craton (from erosion) and may later be subjected to deformation (through collision). In addition, other landmasses (terranes) may be juxtaposed against the craton through plate motion. Click here for a model of plate motions.
Convergent plate boundaries are associated with shallow focus compressive earthquakes (the plates are moving toward each other), deep focus tensile earthquakes (the down going lithospheric slab is falling into the mantle thereby breaking off from the major slab), and low geothermal gradients.
Young compressive plate boundaries are often associated with shallow angles of subduction. The Benioff Zone expresses the angle of subduction. The Benioff Zone is defined by the earthquake foci that occur in the brittle, down going lithospheric slab. This zone can also be modeled by seismic wave velocities (seismic waves travel faster in more rigid rocks i.e. lithosphere rather than asthenosphere).
Volcanism associated with subduction complexes requires water to promote the melting of rocks. Water is squeezed out from the down going slab; this water interacts with the hot rock and causes melting. The water can be found as structurally bound to the mineral or in the pore spaces (including the sedimentary wedge carried down with the lithosphere). Learn more about the Cascade Mountain Range.
Divergent plate boundaries can be considered to be ocean floor factories. This type of plate boundary is associated with normal faults, seismic activity, volcanism, the formation of ocean basins, and high geothermal gradients. Upwelling mantle material cools at Earth's surface (but below sea level) to form ocean floor (peridotites overlain by gabbros overlain by sheeted dike complex and overlain by pillow basalts). Numerous hydrothermal vents are associated with divergent plate boundaries.
Hot spots (also known as mantle
plumes) are one source of molten rock.
This molten material produces volcanic islands. The hot spot beneath
Iceland accounts for the presence of that island, and the Hawaiian
Hot spot accounts for the distribution of the Hawaiian-Emperor Chain.
Hot spots occur beneath the crust, yet the maximum depth is unknown.
The permanence of hot spots (both in location and duration) is also
poorly understood. Watch a video of undersea
volcanic vents or see Woods Hole
Oceanographic Institute videos.
Transcurrent plate boundaries are commonly associated with steeply dipping faults and primarily horizontal movement; this is known as strike-slip motion. Lithosphere is not created or destroyed at this type of plate boundary; shallow focus seismic activity is common. The San Andreas Fault system is a good example of this type of plate boundary.
Summary of plate boundaries; there are three general types of plate boundaries:
|Name||Motion||Type of fault||Example||Volcanism||Seismicity||Lithosphere|
|1. Compressional||→ ←||reverse||Himalayas, Cascade Mt. Range||yes (≈80%)||yes||consumed|
|2. Extensional||← →||normal||mid-ocean spreading ridges||yes (≈15%)||yes||created|
|3. Transcurrent||side by side||transform||San Andreas Fault system||none||yes||unchanged|
Volcanic activity is associated with divergent plate boundaries (15%), convergent plate boundaries (80%), and mantle plumes (5%). Volcanic (extrusive) igneous rocks have relatively small minerals (too small to be seen without a hand lens) as a result of the rapid cooling of lava, whereas plutonic (intrusive) igneous rocks have larger minerals because magma cools more slowly (the heat within the magma is retained by the country rock which acts like a blanket). Lava that cools under water forms pillow lavas.
Read about the 18 volcanoes in the US that are considered dangerous.
Bowen's Reaction Series describes the minerals, rock color, crystallization temperature, and viscosity of the common igneous rocks. Similar minerals may be found in different types of rocks because of dissimilar cooling rates (for example, compare basalt to gabbro, or rhyolite to granite). Different minerals, with similar cooling rates, would also produce different types of rocks (for example, compare gabbro to granite, or basalt to rhyolite). All rocks in Bowen's Reaction Series are igneous rocks because the minerals form through cooling of molten material (lava or magma).
Viscosity is a measure of a material's ability to resist flow. Low viscosity lavas, such as basalt, flow gently onto Earth's surface. High viscosity lavas, such as rhyolitc or andesitic lavas, commonly produce explosive volcanic events.
Volcanoes represent yet another of Earth's safety release valves. Volcanoes release immense heat, quickly, and locally. View the current status of Kilauea, movies of Kilauea, other Hawaiian volcanoes, or the Cascade Volcano Observatory. Another good resource is the Electronic Volcano (hosted by Dartmouth) or the Global Volcanism Program (hosted by the Smithsonian). See the NOAA Significant Volcanic Eruption Database or the USGS listing of US volcanoes that are currently above background level or the Smithsonian Weekly Volcanic Activity Report. The US Geological Survey has an online photo glossary (and real-time video) of volcanic terms, or read about Yellowstone's future. An undersea volcano erupts near Tonga on 18 Mar 09, see the pictures.
PowerPoint slides: Plate tectonics
PowerPoint slides: Igneous Rocks
Please submit your answers to Questions 12-26 from the lab manual (starting on page p. 115).
Common basaltic lava flow textures:
Types of Volcanoes:
Rocks can be physically or chemically weathered. Physical weathering affects the entire solid by the following agents: root pry, frost riving, human activity (walking and ATV), flowing water, winds (sand blasting), daily thermal expansion, and burrowing organisms. Physical weathering produces smaller rock fragments (also known as clasts, sediments, or particles).
Chemical weathering affects the surface of solids by the following agents: acid rain, organic acids (humic acids), and chemically active water. Carbonates (limestone and marble) are more easily weathered by acid rain than silicates (igneous rocks). Small particles have a higher surface area-to-volume ratio than large particles so chemical weathering is more effective at smaller sizes (that is why granulated sugar dissolves more readily than a sugar cube).
Rainwater in New England is acidic. The acid is neutralized in lakes by the carbonate minerals (calcite) that make up the carbonate sedimentary rocks (limestone) and the carbonate metamorphic rocks (marble). See pictures of monuments at Hope Cemetery in Barre, VT; the granite monuments are spectacular and not affected by acid rain.Weathered material is transported in a variety of ways by the agents of wind, water, or ice:
PowerPoint slides: Weathering
PowerPoint slides: Sedimentary structures
In-class assignment related to rock texture and mineralogy.
Use of petrographic microscope to identify rocks by texture and mineralogy. Petrographic microscopes use polarized light. The interaction of polarized light with thin sections of rock (30 microns thin) yield diagnostic optical properties (and vivid colors).
Click here to see how thin sections are made.
Soil is the place where atmosphere, biosphere, hydrosphere, and lithosphere interact. Life is vital to soil and soil is vital to life. It is a complex biogeochemical material a dynamic ecosystem. Soil is produced on the land surface by the interaction of living organisms and organic matter with weathering products.
Soils comprise decayed organic materials, inorganic materials, organisms, moisture, and air. The texture of soil is based on the ratio of sand : silt : clay and is named by plotting these ratios on a triangular diagram. Soil texture plays a significant role in the hydraulic properties of soil. Soil erosion throughout the world is occurring at astonishingly high rates. The soil profile comprises five master horizons (O, A, B, E, C, and R) and numerous subhorizons.
PowerPoint slides: Soil
Some properties of the rock fragments that are of interest to geologists include: roundness, sphericity, size, sorting, surficial features, composition, and packing. The names of clastic sedimentary rocks are based upon the size and composition of the particles that make up the rock, whereas the names of igneous rocks are based upon the size composition of the minerals that make up the igneous rock. See the concept map related to sedimentary rocks.
Many of the properties noted above affect either porosity or permeability (or both). Porosity is a measure of the percent of void space in a solid; porosity values are expressed as a percentage. Pores can hold liquids or gases. When the pores are interconnected the rock is said to be permeable. Liquids or gases can move through permeable rocks.
In lab, we measured the porosity and permeability of various sediments. Use the information (and data) gleaned in lab and describe the relationship between porosity, permeability, packing, particle size, and sorting. In the discussion, account for the range of values obtained in lab and discuss the factors that could have led to the wide range of results. Be as specific as possible and include your own results (even if they did not fit the grand scheme). Follow the guidelines on the handout. Be sure to include a discussion of your observations (including problems, individual observations, and group trends) and interpretations (trends and variability in results). Remember, follow the guidelines.
Note: beware of edge effects with large sediments and pores filled with air for small sediments.
Spring Break—stay safe.
Bi-directional transport (i.e. waves) produces symmetrical ripples. Transport in one direction (by streams or wind) produces asymmetrical ripples. The ripples migrate in the transport direction by removing sediments on the upstream, stoss, (gentle) side and depositing sediments on the downstream, lee, (steep) side of the ripple. This process produces cross-bedding. The thickness of the cross-bedded units produced by streams is on the centimeter scale (and the grains are polished), tidal channels on the tens of centimeters scale, and those units deposited by winds are on the meter scale (and the grains are frosted by pitting with other grains).
Graded beds are represented by a layer of clastic sedimentary rock where the larger particles are found toward the base of the unit and the smaller particles are found toward the top of the unit. Graded beds can form in a stream environment or under conditions where the energy level decreases over time.
The following sedimentary structures can be used as way-up indicators: cross-bedding, sole markings, asymmetrical ripples, symmetrical ripples, rain drop impressions, trace fossils, mudcracks, footprints, mud volcanoes, flame structures, graded beds, mullions, and tool markings.
Through observation of the properties of the sediments one should be able to determine the environment in which the rocks were deposited. Geologists are basically detectives that uncover clues that elucidate the geologic history of an area.
Glaciers have sculpted the landscape for hundreds of millions of years; the most recent glaciation (that ended about 10,000 years ago) is responsible for much of the topography and all of the gravel pits in Vermont. Learn about ancient glacial Lake Hitchcock that is associated with the sedimentary cover in Vermont.
Glaciers advance when more snow accumulates above the snowline than that which is lost in the zone of ablation. Consider advancing glaciers to act like conveyer belts that pluck rocks from beneath the ice and transport the material downhill.
Glacial striations, gouges, roché moutonee, chatter marks, and indicator fans allow geologists to work out the direction of glacial transport. Some of the topographic features attributed to glaciation include: horns, arêtes, paternoster lakes, U-shaped valleys, and spectacular waterfalls. Glaciers also provide a wide variety of depositional environments.
There are some excellent web sites related to glaciology: ICSU World Data Center, the National Snow and Ice Data Center or watch NOVA's slide show that traces the evolution of freshly fallen snow. Click here for a rich resource related to glaciers.
Compasses were used to measure the orientation of the foliated metamorphic rock and the glacial striations. All data were plotted on a map at a scale of 1:10,000. Please submit the map, with orientation data, bar scale, ratio scale, and geologic history.
The hydrologic cycle depicts water flow through Earth's systems through evaporation, condensation, evapotranspiration, runoff, infiltration, and groundwater flow. Groundwater is found below the water table in aquifers; aquifers are porous and permeable rock units that store and transmit water. The water table is the depth at which the pores are saturated (the zone of saturation). The water table is a surface at or below ground level that separates the unsaturated zone above from the saturated zone below. It is a subdued replica of the topography.
One factor that affects groundwater quality depends directly on the rocks that comprise the aquifer. View the EPA list of drinking water contaminants and maximum contaminant levels. The Vermont Department of Health can test your water for a large number of contaminants. Click here to find out what is in the groundwater in your area. Learn about the quality of Vermont's groundwater.
The VT Department of Health Lab is not certified to conduct PFOA water testing. You can find some information about the PFOA contamination in the Bennington area here: http://dec.vermont.gov/commissioners-office/pfoa/communities and find a list of EPA approved Labs for PFOA testing through this link: http://dec.vermont.gov/sites/dec/files/co/pfoa/documents/WellTesting-Outside.pdf.
PowerPoint slides: Groundwater
Groundwater Handout for lab
Please answer Questions 6-12, starting on Page 170 in the handout.
Comments regarding the porosity and permeability lab (last week):
Three points of extra-credit.
Check the UV Index
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