Introduction to Earth Science — Lecture Summaries for Spring 2018


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22 – 26 January 2018 [Week 1]
Introduction to the Course

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. The lab manual is not available online and may be purchased at the JSC Bookstore (yet there are only a few copies left).

See the class syllabus for required readings.

The first lecture will be held on Tuesday, 23 January 2018 in Bentley 206, starting at 1:00 p.m.

The first lab will be held on Wednesday, 24 January 2018 in Bentley 101, starting at 1:00 p.m. Please come to lab prepared to work with topographic maps.

A copy of the textbook and the lab manual are on reserve in the Willey Library.



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.

The Nature of Science

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".

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. 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.

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.

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 established scientifically".


The sun is but one star in the Milky Way Galaxy; it is an average aged star that holds no special position in our galaxy nor is it distinct from other middle-aged stars. The Milky Way Galaxy is one of many spiral barred galaxies that are observed in the universe. There are also irregular, elliptical, and rare ringed galaxies. Stars in the Big Dipper are about 75 light years from Earth (that means that when we look at the Big Dipper today, we see the events that occurred 75 years ago).

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:


PowerPoint slides: Science

PowerPoint slides: Galaxies



PowerPoint slides: Topography

PowerPoint slides: Latitude and longitude

Lab: Topography

Lab: Topographic Maps

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. 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. 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.


Lab Assignment (due 31 Jan 2018): Topographic maps, scales, and cross sections

  1. Submit the topographic map created in lab.
  2. 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).
  3. 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.


29 January–2 February 2018 [Week 2]


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.

Formation of the Universe

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 relic abundance to account for dark matter. Dark matter annihilates into quarks.

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.

A 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.

Read Roger Penrose's brief description of his Conformal Cyclic Cosmology theory, or listen to Lawrence Krauss speak about 'A Universe From Nothing'.

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.

Listen to Brian Greene discuss superstring theory (eleven-dimensional space) or Patricia Burchat discuss dark matter.

Click here if you are interested in learning more about Dr. Peter Higgs and Higgs Boson. Other exotic hadrons have been identified by the LHC.

If you have questions about astronomy, then Ask An Astronomer (or read answers to other questions already posted on that site). Learn about the first observed neutron star collsion.

If you want to get involved in a distributed computing research project, view many of the opportunities in a site maintained by Kirk Pearson, or join the Galaxy Zoo and become a citizen scientist astronomer.

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:


Redshift and the Evolution of the Universe

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.


PowerPoint slides: Redshift

PowerPoint slides: Solar system


PowerPoint slides: Latitude and longitude

Lab: Topography



Lab: Coordinate Systems

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.


Lab Assignment (due 7 February 2018): Map scale and north

Use the map supplied in lab and complete the following:

  1. Determine the dimensions of the Summit Bookstore.
  2. Calculate the ratio scale for the map (based on the dimensions of the Summit Bookstore).
  3. Draw a bar scale of the correct length that is 50 m long and has 10-m divisions.
  4. Draw a true north arrow and a magnetic north arrow properly oriented on the map (in the correct box) and labeled as true north and magnetic north.
  5. Show all work (including calculations for your pace factor) on back of paper and place all results in the proper boxes on the front of the map.
  6. Be sure that units are associated with all numbers (except, of course, the ratio scale, which is unitless).
  7. Print extremely legibly.


5–9 February 2018 [Week 3]

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.


Observations of the Solar System

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.

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.

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.

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!

Some of the consistent observations of the solar system include:

Formation of Earth

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 3668 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 1803 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 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. 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).  Click here to plan for viewing the next meteor shower, then use NASA's Fluxtimator to find the best time to view the most meteors.

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.

The solar system formed by gravitational compression of a spinning cloud of interstellar dust particles. The cloud imploded and material was ejected from this event. The composition of the dust particles ejected from this event followed the chemical condensation sequence (i.e. those materials with lower melting points condensed at greater distances from the sun). Read more about the geochemistry of Titan, one of Jupiter's moons.

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 ship’s drill stem is 10,000 meters long! It won’t 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!



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.

Homework (due 14 February 2018): The unit cell

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: Atoms and minerals

Lab: Minerals


The college closed, due to weather conditions, and lab was unfortunately canceled.


12–16 February 2018 [Week 4]

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. 

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 2018. 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.

Steno's Principles of 1) Superposition, 2) Lateral Continuity, and 3) Original Horizontality were introduced.


Unstable Isotopes and Absolute Dating

The main thrust of today's lecture dealt with absolute dating. 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.


PowerPoint slides: Isotopes

PowerPoints slides: Uniformitarianism


Lab: Relative dating

Lab: 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.


Lab Assignment (due 21 February 2018): Watershed

  • Submit the topographic map handout and answer all questions on that sheet.
  • Clearly show the mathematics for Question 2 on the back of the handout.
  • Use a sharp pencil (or very fine point pen) to draw precise lines that delineate the watershed.



19–23 February 2018 [Week 5]

Please note: class willl be canceled on the Tuesday we return from Winter Break; no class on Tuesday, 6 March 2018.


Gravity and Isostacy

Gravity is a force of attraction; this force is always perpendicular to Earth’s surface and measured in gals. Earth’s 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.

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.

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 Earth’s 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.

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.

First Exam: Thursday, 22 February 2018


PowerPoint slides: Gravity and isostacy

PowerPoint slides: Magnetism


Lab: nothing from the lab manual


Lab: Density

Lab Assignment (due 14 March 2018): Specific Gravity

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.


Class data


Published data

mineral formula
density (g/cm3)
quartz SiO2
Na-rich plagioclase feldspar NaAlSi3O8
Ca-rich plagioclase feldspar CaAl2Si2O8
alkali feldspar (K,Na)AlSi3O8
2.55 - 2.63
biotite K2(Mg,Al)6Si6Al2O20(OH)4
2.7 - 3.3
muscovite K2Al4[Si6Al2O20](OH,F)4
2.77 - 2.88
olivine (Mg,Fe)2SiO4
3.222 - 4.392
pyroxene Ca(Mg,Mn,Fe)Si2O6
3.22 - 3.56
amphibole Ca2(Mg,Fe)4Al[Si7AlO22](OH)2
3.02 - 3.59
galena PbS
7.5 - 7.6



26 February–2 March 2018 [Week 6]

Winter Break–be careful.


5–9 March 2018 [Week 7]

Class canceled on Tuesday, 6 March 2018; see you in lab on Wednesday.

Thursday lecture: magnetism

Daylight Saving Time begins–set clocks ahead one hour at 2:00 a.m. on Sunday, 11 March 2018.

Second Exam: Thursday, 5 April 2018

Field Work: Saturday, 21 April 2018

Final Exam: Thursday, 17 May 2018 at 10:30 a.m.



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