Geol-102: The Earth and Its Structure PDF

Topic 1: The Earth and Its Structure Source: NASA, Public Domain What's in a Smartphone?
your smartphone isn't just a complex electronic device
it's a gold mine,...

Topic 1: The Earth and Its Structure Source: NASA, Public Domain What's in a Smartphone?
your smartphone isn't just a complex electronic device
it's a gold mine, platinum mine, silver mine, copper mine..... Source: apple.com What's in a Smartphone?
in fact, there are at least 75 different chemical elements in a smartphone... What's in a Smartphone?
... and all of the elements used to make a smartphone are obtained from the Earth (top 6 are below) lithium silicon aluminum gold copper iron  "We set out to explore the moon and instead discovered the Earth." - William Anders, Apollo 8 astronaut Image Source: NASA, Public Domain The "Spheres" of the Earth Source: The Conversation 
includes the lithosphere, atmosphere, cryosphere, hydrosphere, and biosphere Components
subsystems interact - mass and energy are stored of the Earth and transported between the components
interactions between the subsystems determine how System climate varies in space and time Atmosphere
contains layers of mixed gases Component Proportion (%) - major gases: nitrogen (N2) nitrogen (N2) 78.1 & oxygen (O2) oxygen (O2) 20.9 - minor gases: argon (Ar) & argon (Ar) 0.93 carbon dioxide (CO2) carbon dioxide (CO2) 0.035 - trace gases: methane (CH4) various trace gases 0.035 & ozone (O3)
water vapour - the most common greenhouse gas along with CO2; varies from trace amounts to several % in local areas of the atmosphere Hydrosphere
comprises all liquid water on Earth - oceans & continental water (lakes, rivers, groundwater)
water covers ~70% of Earth’s surface
source of the water vapour in the atmosphere
ocean circulation strongly influences the Earth system Source: NOAA, Public Domain Cryosphere
cryosphere - ice component of the Earth system - snow, lake and river ice, sea ice, glaciers and ice sheets, frozen ground and permafrost - stores ~75% of Earth’s fresh water Quttinirpaaq National Park, Ellesmere Island
ice and snow reflect much of the solar energy that hits them - they have a high albedo (reflectivity)
less ice and snow at Earth’s surface mean that more solar energy will be absorbed
role of the cryosphere in the earth system best considered separately from the hydrosphere - have different roles Biosphere
all ecosystems on Earth - amount and type of life at any location depends upon local climate conditions
energy contained and transported by living organisms is quite small compared to the amount of radiation that reaches the Earth’s surface - e.g. photosynthesis uses < 0.1% of the sun’s radiation that hits a leaf  Anthropogenic Effects
humans (we are also part of the biosphere) also impact the Earth system, e.g. - release of greenhouse gases through industry, agriculture, other activities - altering surface albedo (reflectivity) of Earth (e.g. deforestation) Source: Getty Images Source: Romeo Gacad/AFP/Getty Images Lithosphere
rocky outer shell of the earth
includes land surface - a key component of Earth system - covers ~30% of Earth’s surface - absorbs and radiates (returns) solar energy
stay tuned for a more specific geological definition Source: Grotzinger et al, Understanding Earth. 2014 Lithosphere Interactions Source: www.theclimategroup.org
properties of land surface strongly influence the Earth system - e.g. water content, vegetation, topography, weathering processes
increased land temperatures increase rate of water evaporation - transport of water vapour to atmosphere increases - increased cloud can reflect more solar radiation, cooling the earth  negative feedback mechanism (decreases severity of change) Lithosphere Interactions - Weathering
CO2 from the atmosphere is consumed during chemical weathering
bicarbonate (HCO3-) produced during chemical weathering is transported to and stored in the oceans - formation of carbonate minerals (e.g., calcite) Figure 8.13 in Panchuk Hydrosphere Interactions
577,000 km3 of water evaporates from Earth’s surface annually - 87% from oceans - 13% from land (lakes and rivers)
same amount falls as precipitation (rain, snow) annually - 79% on oceans - 21% on land
changes in atmospheric temperature influence how much water vapour the atmosphere can hold (higher temperature, higher capacity for water vapour) Source: J. Mcbeth (2019) CC BY 4.0, map © 2019 Google Canada  Cryosphere Interactions
there is a seasonal exchange of water between cryosphere and hydrosphere - melting snow is a major annual source of freshwater - snowfall can account for significant proportion of total precipitation in some areas: ~27% in Saskatoon
positive feedback mechanism (increases severity of change) to Earth system, e.g. - more energy absorbed at earth’s surface  less ice & snow - if less ice and snow  warms Source: http://www.ski-i.com/blog/ski-safety-tips-2/ surface more Photo: J. McBeth (2019)  Biosphere Interactions
plants interact with the atmosphere - absorb solar radiation and release heat - release water vapour through transpiration - absorb CO2, generate O2
(micro)organisms regulate atmospheric composition - produce or consume CO2 and methane (CH4)
dissolved nutrients (e.g. N, P, Si, Fe, Zn) in the oceans feed plankton (base of the food chain)  nutrient upwelling in ocean currents creates enhanced bioproductivity Example: How the “spheres” are connected (lithosphere) (cryosphere) (hydrosphere) (atmosphere) (biosphere) Figure 16.2 in Panchuk Summary – The Earth System
earth system is composed of many "spheres" - lithosphere, atmosphere, cryosphere, hydrosphere, and biosphere
atmosphere - layers of mixtures of gases
hydrosphere - all liquid water: oceans, lakes and groundwater - ocean circulation strongly influences Earth system
cryosphere (snow & ice) - different from hydrosphere - albedo (reflectivity) and loss of polar ice Summary – The Earth System
biosphere - all living organisms - produce/consume water, CO2 + other compounds - anthropogenic effects
lithosphere - landscape can affect Earth system - surficial weathering  dissolved elements & nutrients, e.g. carbon cycle
all subsystems interact  feedback loops (positive, negative)  climate varies in space and time  Note: This course will not cover all of the material in Suggested Readings each chapter of the textbook. These reading recommendations highlight material relevant to this Textbook course. Chapter 16
Introduction
Section 16.1: What is the Earth System?
Section 16.5: Humans in the Earth System Workbook Chapter 16 - vocabulary and review questions  Source: geologypage.com
"geo" (Earth) + "logia" (study) = the study of the Earth
describes the structure and composition of the Earth and the processes that have shaped it through time The Structure of the Earth Earth’s layers: crust, mantle, core (inner and outer) The layers of Earth (Credit: www.phys.org)  Layered Earth Crust Solid, 0-40 km, 0.4% of mass Mantle Solid, 40-2890 km, 67.1% of mass Outer Core Liquid, 2890-5150 km, 30.8% of mass Inner Core Solid, 5150-6370 km, 1.7% of mass Source: Grotzinger et al, Understanding Earth. 2014  Layered Earth Crust 2.8 g/cm3 silicates Mantle 4.5 g/cm3 dense silicates, oxides Outer Core 10-12 g/cm3 Inner Core ~13 g/cm3 iron-nickel alloy Source: Grotzinger et al, Understanding Earth. 2014 8 elements account for about 99 wt. % of Earth     
 http://commons.wikimedia.org/wiki/File:Periodic_table_(polyatomic).svg Review workbook appendix on chemistry: https://openpress.usask.ca/geolworkbook/back-matter/appendix-i-chemistry/ But how do we know? Earth’s Composition
has been inferred (determined from evidence) from: - seismic studies - study of earthquake waves moving through the Earth (geophysics) - knowledge of Earth’s overall (average) density - samples of the Earth’s crust and mantle and meteorites Source: Fletcher et al. (2014) Introduction to Physical Geology  Layered Earth Crust Solid, 0-40 km, 0.4% of mass Mantle Solid, 40-2890 km, 67.1% of mass Outer Core Liquid, 2890-5150 km, 30.8% of mass Inner Core Solid, 5150-6370 km, 1.7% of mass Source: Grotzinger et al, Understanding Earth. 2014 Two Types of Crust
crust is not homogeneous, it is also layered
mainly due to differences in density less dense continental continental crust is less crust "floats" on denser mantle dense than oceanic crust 
   oceanic crust continental crust (3.0 g/cm3) (2.8 g/cm3)   mantle  "Moho" (3.4 g/cm3)  Continental vs. Oceanic Crust 
   oceanic crust continental crust (3.0 g/cm3) (2.8 g/cm3)   mantle  "Moho" (3.4 g/cm3) 
continental crust - enriched in minerals (e.g. feldspar and quartz) with lighter elements, e.g. K, Na, Al, Si  "felsic"
oceanic crust - enriched in minerals composed of slightly heavier elements, e.g. Mg, Fe  "mafic"
boundary between the crust (continental / oceanic) and mantle is called the Mohorovičić discontinuity ("Moho")  Layered Earth Crust Solid, 0-40 km, 0.4% of mass Mantle Solid, 40-2890 km, 67.1% of mass Outer Core Liquid, 2890-5150 km, 30.8% of mass Inner Core Solid, 5150-6370 km, 1.7% of mass Source: Grotzinger et al, Understanding Earth. 2014 Mantle
earth's mantle can be further subdivided into the upper and lower mantle
within the upper mantle, two important subdivisions - uppermost mantle (solid and rigid) - semi-molten (partially melted) mantle
"asthenosphere" = soft, ductile, viscous layer ~180 km thick just below uppermost mantle Source: USGS  Lithosphere & Asthenosphere "lithos" = stone (Greek) "asthenos" = weak Lithosphere vs Crust: an orange peel analogy crust: orange peel (rigid) uppermost mantle: white peel (also rigid) upper mantle: white peel + Source: USGS squishy orange
"lithosphere" = uppermost mantle + crust - rigid layer asthenosphere: squishy orange underneath lithosphere: whole peel (orange + white) (rigid) ~100 km thick Orange Peel ©2017-2018 Margarita Morrigan Temperature gradient in the Earth Source: Karla Panchuk (2018) CC BY 4.0, modified after Steven Earle (2016) CC BY 4.0 Why is the Earth's interior so hot?
radioactive decay
“primordial heat” - residual heat remaining from when the Earth first formed Source: Karla Panchuk (2018) CC BY 4.0, modified after Steven Earle (2016) CC BY 4.0 Rocks in the asthenosphere are moving Source: USGS
in the asthenosphere, rocks are plastic (ductile) and can convect (move in a loop, hot rocks rising, cool rocks sinking)
similar to boiling water in a pot or heating air in a convection oven except much more slowly!  Mantle Plumes ("Hotspots")
columns of hot magma rise from core-mantle boundary (base of mantle)
volcanism in Hawaii is thought to result from a mantle plume   
 Source: Fletcher, Gibson & Ansdell (2014) Introduction to Physical Geology  Layered Earth Crust Solid, 0-40 km, 0.4% of mass Mantle Solid, 40-2890 km, 67.1% of mass Outer Core Liquid, 2890-5150 km, 30.8% of mass Inner Core Solid, 5150-6370 km, 1.7% of mass Source: Grotzinger et al, Understanding Earth. 2014 Earth’s Magnetic Field
generated by convection in liquid outer core Source: Fletcher, Gibson & Ansdell (2014) Introduction to Physical Geology Summary - Structure of the Earth
layered Earth - layers have different compositions - crust, mantle, core
each layer has different properties (e.g., density, physical state (liquid/solid)
a handful of elements account for ~99 % of Earth's mass - crust: enriched in lighter elements, e.g. Si, Al - core: concentrated with heavier elements, e.g. Fe, Ni
each layer is also inhomogeneous - crust: continental crust ("felsic"), oceanic crust ("mafic") - mantle: upper mantle, lower mantle; ductile & rigid layers - core: outer (liquid, earth's magnetic field), inner (solid) Summary - Structure of the Earth
lithosphere - Earth’s crust + uppermost mantle - acts as a solid and rigid "plate"
asthenosphere - soft, partially molten, viscous layer in the upper mantle - just underneath the lithosphere
temperature generally increases with depth into the Earth "geothermal gradient"
rocks in the Earth’s mantle (asthenosphere) convect
mantle plumes - columns of hot magma that rise up from base of mantle through the crust (e.g. Hawaii)  Note: This course will not cover all of the material in Suggested Readings each chapter of the textbook. These reading recommendations highlight material relevant to this Textbook course. Chapter 3
Introduction
Section 3.1: Earth’s layers: Crust, Mantle, and Core
Section 3.3: Earth’s Interior Heat Workbook Chapter 3 - vocabulary and review questions Additional Materials: The Earth & Its Structure 13 Misconceptions About Climate Change - an amusing 7-minute video highlighting some misconceptions about climate change The Discovery of the Earth's Layers - a 6-minute video explaining how the Earth's layers were discovered, and what they are Additional Materials: The Earth & Its Structure Why Does the Earth Have Layers? - a short video explaining how scientists think the Earth originally formed and why When Did the Continents Form? - an easy-to-read-article looking at the linkages between the Earth's internal structure and the Earth system, and when we think the first continents appeared in the early history of the Earth Bad Geology Movie
summary: an unknown force has caused the earth's inner core to stop rotating. With the planet's magnetic field rapidly deteriorating, Earth's atmosphere literally starts to disintegrate with catastrophic consequences.
use your knowledge to find all of the reasons why this Hollywood blockbuster is not https://en.wikipedia.org/w/index.php?curid=3772912 geologically sound!    

  
    Topic 2: Minerals  What Is a Mineral?
a naturally-occurring, inorganic, crystalline solid with a definite, but sometimes variable, chemical composition
the building blocks of all rocks, i.e. all rocks are composed of one or more minerals ice pyrite malachite Source: http://www.mindat.org/ Elements & Minerals
elements are the fundamental building blocks of all minerals
all minerals are composed of one or more http://www.chemicool.com/ pyrite elements [FeS2] malachite ice [Cu2CO3(OH)2] [H2O] Naturally-occurring & Inorganic
minerals are formed in nature, by geological processes
not produced by living organisms (inorganic) - example: diamond [C] natural natural synthetic © Rob Lavinsky Crystalline Solid
the atoms composing minerals are arranged in an orderly, repeating, three-dimensional structure Source: Steven Earle (2015) CC BY 4.0 Source: College Physics (2012), OSCRiceUniversity, OpenStaxCollege. CC BY 4.0. Chemical Composition
a mineral’s chemical composition is its chemical formula
chemical composition of a mineral is either fixed or varies within defined limits
some minerals have fixed compositions - examples: halite [NaCl] or quartz [SiO2]
others can exhibit a range of compositions - example: feldspar [(K,Na)AlSi3O8] potassium sodium feldspar feldspar [KAlSi3O8] [NaAlSi3O8] Source: Wikipedia Commons Source: imgur.com Impurities in Minerals
impurities (minor quantities of other elements - also called "trace elements") can alter the appearance of minerals - example: different varieties of corundum [Al2O3] include ruby and sapphire, which have different colours (and value!) due to impurities Sapphire Ruby [Al2O3 + Fe/Ti] Corundum [Al2O3] [Al2O3 + Cr] Source: http://www.mindat.org/ Mineral vs. Compound  
 

  


  

  
 
 


 
  
 
 


  compounds can be organic; all minerals are inorganic  compounds don’t necessarily have regular crystal structures, i.e. they don’t have to be solid (e.g. liquid water is a compound); all minerals are solid  compounds and minerals can be produced naturally or synthetically in a lab; minerals always occur naturally  minerals are a subset of compounds  How do minerals form?
minerals form by crystallization, where atoms of a gas or liquid combine to form a solid
crsystallization can occur in many ways, e.g. cooling of a molten rock (magma) or precipitation from a fluid Source: Wikimedia user JJHarrison (2009) CC BY-SA 2.5  Classes of Rock-Forming Oxides Hematite [Fe2O3] Minerals Images Silicates Carbonates Sourced Calcite [CaCO3] from: Feldspar [KAlSi3O8] mindat.org Native Elements Copper [Cu] Halides Sylvite [KCl] Phosphates Image source: Apatite [Ca5(PO4)3(F,Cl,OH)] Wikimedia user Digon3 (2009) Sulfides CC BY-SA 3.0 Pyrite [FeS2] Sulfates Gypsum [CaSO4·2H2O] Source: www.britannica.com Carbonates
carbonate ion (CO32-) is the building block of carbonates Example: calcite
most common carbonates: - calcite: CaCO3 - dolomite: CaMg(CO3)2 Source: Karla Panchuk (2018) CC BY-SA 4.0. Photos by Rob Lavinsky, iRocks.com, CC BY-SA 3.0. Oxides
oxygen is bonded to atoms or cations of other elements - examples: Fe3+, Cr3+, Ti4+
oxides are a principal source of metals for industry Spinel [MgAl2O4] Hematite [Fe2O3] Uraninite [UO2] Gem mineral Image Sources: mindat.org Source: Karla Panchuk (2018) CC BY-NC-SA 4.0. Photos by R. Weller/ Cochise College.  Sulfides
basic building block is the sulfide anion (S2-) - bonded to metallic cations
principal ore of many valuable metals: - chalcopyrite [CuFeS2] - sphalerite [ZnS] - millerite [NiS]
sulfide mineral weathering is a global environmental issue Image source: Mike Moncur (2006) https://uwaterloo.ca/ Source: Karla Panchuk (2018) CC BY-NC-SA 4.0. Photos by R. Weller/ Cochise College. Sulfates
include sulfate ion (SO42-) bonded with cationic metals - examples: Ca2+, Ba2+, Mg2+, Fe2+ and others
commonly occur in high-evaporation environments, e.g. deserts (evaporite deposits)
common examples: Source: Karla Panchuk (2018) CC BY-NC-SA 4.0. Mineral Hydration
some minerals incorporate water molecules in their crystal structure ("hydrated") Source: Karla Panchuk (2018) CC BY-NC-SA 4.0.
still classified within the various mineral classes, e.g. gypsum is a hydrated sulfate mineral  Source: thefactfactor.com Halides
halide anions bonded to metallic cations - anions: F-, Cl-, Br-, I- - cations: Na+, K+, Ca2+, Mg2+
halide minerals commonly occur in evaporite deposits
economic examples: - halite: NaCl - fluorite: CaF2 - sylvite: KCl (potash) Image Source: PotashCorp. http://upload.wikimedia.org/wikipedia/commons/0/0c/Mineral_Silvina_GDFL105.jpg Source: Karla Panchuk (2018) CC BY-NC-SA 4.0.  Native Elements
often occur in very small amounts in rock (e.g. gold)
example of native gold - “gold nuggets”
not all metals are present in nature as native elements Native Silver http://www.mineralogicalrecord.co m/newpix/Silver,-Morocco.jpg Gold nugget – goldrushnuggests.com Gold in quartz – Wikipedia Commons Native Platinum https://www.crystalclassics.co.uk/produ ct/native-platinum-6570/ Source: Karla Panchuk (2018) CC BY-SA 4.0. Silicates
silicate minerals comprise ~90% of Earth’s crust - also account for ~1/3 of all known minerals
basic building block of all silicate minerals: silicon-oxygen tetrahedron (SiO4-4) - silicon ion (Si4+) surrounded by four oxygen ions (O2-) -4 SiO4 Image from Fletcher, Gibson & Ansdell (2014) Introduction to Physical Geology, Canadian Edition. Wiley. Silicates
silicate minerals are subdivided into several major groups depending on how their silicon-oxygen tetrahedra are arranged in the crystal structure, e.g. - framework silicates - chain silicates - sheet silicates Image from Fletcher, Gibson & Ansdell (2014) Introduction to Physical Geology, Canadian Edition. Wiley. Framework Silicates
Si-O tetrahedra form a three- dimensional framework - minerals tend to be very hard (and strong)
this group comprises ~75% of the earth's crust
important examples: - quartz [SiO2] - feldspar: - K-feldspar [K(AlSi3)O8] - plagioclase [Na(AlSi3)O8] Image from Fletcher, Gibson & Ansdell (2014) [Ca(Al2Si2)O8] Introduction to Physical Geology, Canadian Edition. Wiley. !%"
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Chain Silicates Images from Fletcher, Gibson & Ansdell (2014) Introduction to Physical Geology, Canadian Edition. Wiley. single-chain double-chain
Si-O tetrahedra form single or double chains
chemical composition can vary based on cation substitutions, e.g. K+, Na+, Ca+2, Mg+2, Fe+2, Fe+3
silicate chains tend to strengthen crystal structure in 1 direction, but planes of structural weakness can develop in other directions  Pyroxene (augite) (Ca,Na)(Mg,Fe,Al,Ti)(Si,Al)2O6 Amphibole (hornblende) (Ca,Na)2(Mg,Fe,Al)5(Al,Si)8O22 (OH)2 Source: Karla Panchuk (2018) CC BY-NC-SA 4.0. Photos: sandatlas.org / e-rocks.com Sheet Silicates
continuous sheets of Si-O tetrahedra form a layered hexagonal network - spaces between the layers can be occupied by a variety of cations, e.g. K+, Na+, Ca+2, Mg+2, Fe+2, Fe+3
silicate layers are strong within Image from Fletcher, Gibson & Ansdell (2014) Introduction to layer but very weak between Physical Geology, Canadian Edition. Wiley. layers, e.g. layers can easily "slide" on each other
examples: mica - biotite (brown, black) - muscovite (grey, white) Wikipedia Creative Commons CC BY 4.0 Source: Karla Panchuk (2018) CC BY-NC-SA 4.0. Top left- modified after Steven Earle (2015) CC BY 4.0. Top right- modified after Klein & Hurlbut (1993). Photos by R. Weller/ Cochise College Physical Properties of Minerals
used to identify minerals in field and laboratory
colour
hardness
cleavage / fracture
lustre
streak
specific gravity (density)
crystal form
other properties (e.g. magnetism, acid reaction)  Sources: mindat.org and Wikipedia Commons Colour
some minerals have a distinct colour pyrite turquoise
however, many others display a range of colours, e.g. - quartz [SiO2] quartz (amethyst) quartz (citrine) - K-feldspar [KAlSi3O8] K-feldspar K-feldspar *** BUT colour is not always reliable for mineral identification!!  Source: Wikipedia Commons Silicate Colours
light – "felsic" (important: remember this!!) - high Si content; low Fe + Mg content - examples: feldspar, quartz feldspar & quartz
dark – "mafic" (important: remember this!!) - high Fe + Mg content; lower Si content - examples: amphibole, pyroxene amphibole & pyroxene ocean crust (mafic) continental crust - rich in mafic (felsic) - enriched minerals in felsic minerals  Hardness
evaluated using Mohs scale of mineral hardness (1-10) - based upon how easily a mineral surface can be scratched Image from Fletcher, Gibson & Ansdell (2014) Introduction to Physical Geology, Canadian Edition. Wiley. "The Geologist Can Find Amazing Fossils Quickly Through Correct Diggings" Cleavage
the way a mineral tends to break along planar surfaces  determined by its crystal structure
surfaces known as "cleavage planes"
caused by the planar alignment of weaker bonds between atoms in the crystal lattice
how to distinguish cleavage planes from fractures? Cleavage Fracture surfaces generally smooth surfaces generally curved, and planar broken, and rough surfaces are often reflective surfaces are non-reflective Cleavage vs. Crystal Faces cracks in this mineral are cleavage planes, repeating throughout in the same pattern cleavage plane crystal face (not cleavage) - repeated - single surface Cleavage (mica) Source: Karla Panchuk (2018) CC BY-SA 4.0. Cleavage diagram modified after M.C. Rygel (2010) CC BY-SA 3.0 Cleavage Planes mica (sheet silicate) halite (halide) pyroxene (single-chain silicate) amphibole calcite (carbonate) (double-chain silicate)  (salt) Source: Karla Panchuk (2018) CC BY-SA 4.0. Cleavage diagrams modified after M.C. Rygel (2010) CC BY-SA 3.0 Fracture
found in minerals with no naturally occurring planes of weakness (e.g. some framework silicates)
mineral tends to break along curved or irregular surfaces
example: quartz Lustre
a description of how light interacts with a mineral surface
a variety of descriptors can be used, e.g. - metallic - shiny like metal - vitreous - clear (or nearly clear) like glass - adamantine - like the brilliant sparkle of diamonds
lustre can vary across different samples of the same mineral (be careful in mineral ID) Image Sources: https://en.wikipedia.org/wiki/Lustre_(mineralogy)  Lustre Terms GREASY METALLIC RESINOUS pyrite amber (note: not a opal jade mineral, but good example of resinous!) VITREOUS SILKY ADAMANTINE PEARLY gypsum mica diamond halite quartz https://en.wikipedia.org/wiki/Lustre_(mineralogy) Streak
colour of the powdered mineral
by scratching the mineral on an abrasive surface, you can obtain a "streak" of mineral powder
abrasive surface is typically a white ceramic plate ("streak plate") hematite
colour of the powdered streak can help to identify minerals
often useful for minerals with Fool’s gold! metallic lustre
mineral must be softer than streak plate! pyrite Specific Gravity
ratio of density of a mineral (in g/cm3) relative to density of water (1 g/cm3)  specific gravity is unitless
some minerals will definitely seem heavier than others!
strongly related to the chemical composition of the mineral Galena [PbS] Specific Gravity Mineral Formula (unitless) galena PbS 7 calcite CaCO3 2.7 feldspar NaAlSi3O8 2.61 quartz SiO2 2.65 Rob Lavinsky, iRocks.com – CC-BY-SA-3.0 gold Au 19.2 Crystal Form
geometry of a crystal - external expression of internal arrangement of atoms in crystal structure - shape of crystal or crystal cluster Other Useful Mineral Properties for ID 
 

magnetism - magnetite [Fe3O4]
reaction to acid - carbonates
smell 
- sulfur      
taste  BUT DON’T LICK THE ROCKS - salty: halite [NaCl] Many minerals contain toxic metals! Not to mention the ones in labs have been - bitter: sylvite [KCl] handled by hundreds of students… Summary – Minerals
definition of a mineral - a naturally-occurring, inorganic, crystalline solid
all minerals composed of one or more elements - small impurities can change mineral properties!
several classes of minerals, e.g. silicates, carbonates, oxides, sulfides, sulfates, halides, native elements
silicates comprise 90% of the earth's crust - basic building block: Si-O tetrahedron
silicate mineral groups based on arrangement of Si-O tetrahedra (framework silicates, single & double-chain silicates, sheet silicates) Summary – Minerals  physical properties of minerals useful in identifying minerals in the field or lab - colour - 
 - cleavage / fracture - lustre - streak - specific gravity - crystal form - other properties (e.g. magnetism, acid reaction)  Note: This course will not cover all of the material in Suggested Readings each chapter of the textbook. These reading recommendations highlight Textbook material relevant to this course. Chapter 5
Introduction
Section 5.1: Electrons, Protons, Neutrons, and Atoms
Section 5.3: Mineral Groups
Section 5.4: Silicate Minerals
Section 5.5: Formation of Minerals
Section 5.6: Mineral Properties Workbook Chapter 5 - vocabulary and review questions Additional Materials: Minerals The Evolution of Minerals and Life - an interesting article featuring an interview with a distinguished mineralogist who discusses his thoughts on how minerals may have formed in the early history of universe and whether minerals can evolve with time, just like life  Source: Karla Panchuk (2017) CC BY-SA 4.0. Topic 3: Rocks and the Rock Cycle (Igneous Rocks) What Are Rocks?
naturally-occurring solid aggregates of minerals, or in some cases, non- mineral solid matter Source: isleofmullcottages.com
minerals have been - cooled and crystallized together - cemented together Source: The Geological Society of London - heated and squeezed together Source: https://en.wikibooks.org/ wiki/Historical_Geology/Sedimentary_rocks  Identification of Rock Types Determined by three main factors:
origin Source: R. Weller/ Cochise College (2011) Permission for - how did the rock form. e.g. non-commercial educational use. (labels added) from molten rock, weathering, or from heating and squeezing?
composition - which minerals? - in what proportion? - overall (bulk) composition (e.g. felsic vs. mafic)
texture - size and shape of mineral crystals - patterns of mineral grains or other features in the rock, known as “rock fabric” Major Rock Types  Source: USGS (1996) Public Domain Source: J. D. Griggs, U. S. Geological Survey (1985) Public Domain Igneous Rocks - e.g. basalt, granite Half Dome, Yosemite National Park Source: Wikipedia CC BY 4.0 Origin of Igneous Rocks
igneous rocks form from the cooling of molten rock (magma) and come from two kinds of environments
extrusive igneous rocks: magma (lava) and volcanic ash are extruded / ejected at Earth’s surface
intrusive igneous rocks: magma cools and solidifies at depth below Earth’s surface in a magma chamber Types of Igneous Intrusions
intrusive bodies come in many different shapes and sizes
pluton - a generic term for an intrusive body of variable shape and size, e.g. magma chamber
batholith - a massive intrusive body, much larger than a pluton (> 100 km2), and typically located deeper in the crust  Pluton and Batholith Source: variscancoast.co.uk Source: Edwin Remsberg, Getty Images pluton Cornubian batholith, UK Sierra Nevada batholith, USA Source: Wikipedia Commons Types of Igneous Intrusions
dike (dyke) - a sheet of rock formed in a fracture of a pre- existing rock; a semi- planar intrusion cutting across pre- existing layers of rock
forms by intrusion (injection) of magma into fractures in rock
exhibit a wide range of thicknesses and lengths  Dikes Source: U.S. National Park Service Students examining an exposed dike on Mt. Etna, Source: GeologyScience.com Source: geologypics.com Igneous Rock Classification
igneous rocks are classified based upon:
origin - intrusive or extrusive?
composition - mineralogy - proportion of each mineral - overall (bulk) composition
texture - shape, size, arrangement, and distribution of minerals - other features such as the presence of air bubbles, large crystals, etc.  "Rapidly" could be Igneous Rocks and Texture anywhere from minutes to months "Slowly" means thousands or perhaps millions of years, in some cases  Note: "slow cooling" means 1000s or millions Intrusive Igneous Rocks of years, in some cases  formed deep within the Earth  cool and solidified slowly  mineral crystals can grow to larger sizes because of the slow cooling  texture  produces coarse-grained rocks   








 
 




 


 

   Source: https://www.geologypage.com/2019/05/granite-rocks.html  felsic Intrusive Igneous Rocks
magmas can vary in chemical composition, i.e. - felsic (light-coloured) - Si, Al-rich intermediate - e.g. granite - intermediate (between felsic & mafic) - e.g. diorite - mafic (dark-coloured) - Fe, Mg-rich - e.g. gabbro Credit: USGS mafic Types of Intrusive Igneous Rocks granite pegmatite diorite gabbro 
 
  
in the stone industry, any hard silicate rock is often called "granite", even though it is not "Titanium Granite" "Nero Marinace Granite" "White Sparkle Granite" - NO. Actually a gneiss - NO. Actually a - YES!! (metamorphic) metaconglomerate (metamorphosed sedimentary rock)   
 
  
 

Extrusive Igneous Rocks   

   formed on or near the Earth's surface  cool and solidified rapidly  mineral crystals do not have time to grow in size  texture  produces glassy to fine-grained rocks   








  



  
  

 Source: https://geologyscience.com/rocks/basalt/ Extrusive (Volcanic) Igneous Rocks felsic
molten rock (lava) erupts on or ejects at Earth’s surface
lavas can vary in chemical composition, i.e. Credit: Tuomo Manninen intermediate - felsic (light-coloured) - Si, Al-rich - e.g. rhyolitic lava  rhyolite - intermediate (between felsic & mafic) - e.g. andesitic lava  andesite Credit: USGS mafic - mafic (dark-coloured) - Fe, Mg-rich - e.g. basaltic lava  basalt Credit: sandatlas.com  Other Extrusive (Pyroclastic) Materials
pyroclasts: fragments of lava ejected into air during eruption
e.g. volcanic ash - small fragments (< 2 mm) resulting from lava suddenly cooling and shattering in Mt. Cleveland eruption, Alaska Credit: USGS volcanic explosions - largely composed of glass (non-crystalline)
e.g. volcanic bombs - fragments > 64 mm in dia. - cool and solidify before hitting ground Types of Extrusive Igneous Rocks rhyolite pumice andesite basalt obsidian Composition of Igneous Rocks / summary:    
  
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  Intrusive / Extrusive Equivalents
for many igneous rocks, there are often intrusive and extrusive equivalents FELSIC INTERMEDIATE MAFIC intrusive (coarse-grained) granite diorite gabbro extrusive (fine-grained) rhyolite andesite basalt Textures of Igneous Rocks
size, shape, arrangement, and distribution of minerals
visually estimate grain size
we will focus on two main textures: 1) coarse-grained granite 2) fine-grained rhyolite Summary – Rocks and Igneous Rocks  rock - a naturally-occurring aggregate of minerals  3 major kinds: igneous, sedimentary, metamorphic  origin of igneous rocks - intrusive vs. extrusive   
 


   
     
  
 

 
  
     
 
    
   textures: coarse-grained, fine-grained  Note: This course will not cover all of the material in Suggested Readings each chapter of the textbook. These reading recommendations highlight Textbook material relevant to this course. Chapter 7
Introduction
Section 7.1: magma and magma formation
Section 7.2: crystallization of magma
Section 7.3: classification of igneous rocks
Section 7.4: intrusive igneous bodies Workbook Chapter 7 - vocabulary and review questions  Source: Karla Panchuk (2017) CC BY-SA 4.0. Topic 3: Rocks and the Rock Cycle (Sedimentary Rocks) Sedimentary Rocks - e.g. sandstone, limestone, chalk The Wave, Source: AZ Central White Cliffs of Dover, UK. Source: UPI El Torcal de Antequera, Málaga, Spain. Source: Fernando Domínguez Cerejido Sedimentary Rocks
most of Earth’s surface is covered with layers of loose sediment
over millions of years, these sediments can be compressed and lithified (turned into rock)  sedimentary rock
>75% of the land surface is composed of sedimentary rock Sedimentary Rocks
preserve evidence of their source environments and depositional processes
contain direct and indirect Excavating a triceratops vertebrae in evidence of life and its sandstone, Grasslands National Park, SK evolution - fossils!
help us understand geological history
are the source of important resources, including metals, Steven Earle building materials, and energy Triassic limestone being quarried for cement at Texada Island, BC How Are Sediments Made? Weathering
disintegration of rock into smaller pieces or components by natural chemical and physical processes
chemical weathering breaks K-feldspar down rocks through chemical reactions (often involving water), e.g. dissolution, oxidation CO2 + H2O = H2CO3 - often results in the creation of new minerals HCO3- + SiO2 + K+ Fe + O2 = rust kaolinite (clay) Source: carparts.com5)  Weathering
physical weathering - breaks rocks apart mechanically without changing chemical composition - increases surface area abrasion ice wedging tree roots Source: thinglink.com Source: arnwine.weebly.com Source: blendspace.com5) Source: geo-fu-berlin Surface processes: weathering, erosion / transportation, deposition Source: Fletcher, Gibson & Ansdell (2014) Introduction to Physical Geology, Canadian Edition. Wiley.  Common Types of Sediments
weathered and eroded fragments of rocks & minerals, precipitates, or biological material  "sediments" clastic chemical biochemical Source: Fletcher, Gibson & Ansdell (2014) Introduction to Physical Geology, Canadian Edition. Wiley.  Clastic Sediments
physically weathered and eroded pieces of rocks and minerals - particles can vary significantly in size: boulders  cobbles  gravel  sand  silt  clay
weathering intensity controls mineralogy of sediments Weathering Intensity  
          
        
     Source: Fletcher, Gibson & Ansdell (2014) Introduction to Physical Geology, Canadian Edition. Wiley.  Chemical and Biochemical Sediments
chemical weathering dissolves ions which accumulate in water
chemical and biological reactions precipitate minerals from these dissolved ions Chemical Sediments Biochemical Sediments produced by inorganic produced by biological precipitation reactions precipitation processes Comet exhibiting coma (tail) Source: Fletcher, Gibson & Ansdell (2014) Introduction to Physical Geology, Canadian Edition. Wiley. Chemical Sediments
chemical sediments form from mineral precipitation due to evaporation
e.g. seawater, or other water with high salt concentrations
common evaporite minerals: halite, calcite, gypsum, potash Source: Wilson44691 (CC BY-SA 3.0) Biochemical Sediments
biomineralization - organisms use dissolved ions or molecules in water to produce shells or skeletons
minerals can also precipitate due to environmental conditions created by organisms Source: sandatlas.org Change in Sediments
sediments are transported across Earth’s surface from a source to a depositional environment
sediments change as they are transported due to gravity, physical and chemical weathering processes Sediment Transport & Size
in a stream, particles are transported downhill (with gravity) and deposited elsewhere
stream current velocity dictates the size of particles that are transported or deposited at a given location - strong currents (>50 cm/s) - carry gravel or larger cobbles - moderate currents (20–50 cm/s) - carry and deposit sand - weak currents ( 25.6 cm)
these are the coarsest sediments
relatively few sedimentary environments where stream / river currents are strong enough to transport gravel - e.g. mountain streams, rocky beaches with high waves, and glacial meltwater
note: breccia = conglomerate with angular fragments Source: rocksminerals.flexiblelearning.auckland.ac.nz Sandstone (clastic) quartz arkose sandstone sandstone   
  
composed of lithified sand (0.062 to 2 mm dia.) particles
sand particles are transported by moderate-energy currents - e.g. rivers and streams, waves at shorelines, wind
quartz sandstone = pure quartz sand; arkose sandstone = a mixture of quartz and feldspar sand
often porous (serve as reservoirs for hydrocarbons) Mudstone and Shale (clastic) Source: Grotzinger & Jordan (2014) Understanding Earth, 7th edition. Freeman. shale shale mudstone
composed of varying proportions of clay- and silt-sized particles ( 800
C)  these temperatures typically found at depths of 10–30 km (in the crust) Source: http://earthsci.org/mineral/rockmin/meta/meta.html Heat and Metamorphism
heat results in breaking of chemical bonds in existing minerals and the formation of new minerals and rocks
e.g. + + feldspar pyroxene garnet quartz shale garnet-mica schist Sources: Wikipedia, Wikimedia Commons, minerals.net, geology.net  Heat and Metamorphism
heat reduces the strength of protolith rocks, makes them "softer"
rocks can become ductile, just like plasticene, leading to deformation
deformed metamorphic rocks can exhibit very complex folding Folded marble in the Connemara Metamorphic Complex, Ireland. Source: Martin Feely. Role of Fluids
water and carbon dioxide are present in varying amounts in rocks: - along grain boundaries - in pore spaces Source: Maine.gov
fluids accelerate chemical reactions by transporting ions rapidly from one place to another Metamorphism in the Kitchen
cooking is metamorphic!
adding liquids makes a big difference to the end product
changes both the elemental composition and chemistry of what forms Source: https://natashaskitchen.com/easy-pumpkin-cake-recipe/ Sources of Fluids
there are several sources of fluids in rocks: - groundwater - trapped in sedimentary rocks - released from magmas - breakdown of hydrated minerals (containing water) Role of Time
it takes time for deformation and recrystallization to occur in rocks
rocks recrystallize until they reach equilibrium
metamorphism may take anywhere between years and millions of years (depends on conditions of metamorphism) Another cooking analogy: same temperature and pressure, but different toasting time – the only difference between bread and burnt toast (and everything in between) Source: milosluz/iStock Role of Pressure
pressure can alter the mineralogy and texture of rocks - controls which minerals form and which are stable - minerals formed at higher pressure have higher density Source: Karla Panchuk (2018) CC BY 4.0, modified after Materialscientist (2009) CC BY-SA 3.0  Types of Pressures / Stresses
confining (lithostatic) pressure – pressure applied equally everywhere on a body due to weight of overlying rock
directed pressure (differential stress) – unequal pressure applied to a body, e.g. tension or compression
shear stress – opposing forces creating slippage along a plane Source: Steven Earle CC-BY 4.0  Directed Pressure Newly-formed metamorphic Original texture minerals (e.g. mica) forced (e.g., sedimentary to grow perpendicular to layering) the main pressure direction Pressure Pressure Source: Steven Earle (2015) CC BY 4.0 direction of new mineral formation of metamorphic growth texture ("fabric") Metamorphic Fabric
spatial and geometric arrangement (orientation) of minerals in a rock, e.g. layering, banding, etc.
created in response to directed pressure (differential stress)
determined by properties of the minerals in the rock: - size - shape - arrangement - chemical compositions of minerals Source: Fletcher, Gibson & Ansdell (2014) Introduction to Physical Geology, Canadian Edition. Wiley. Development of Metamorphic Fabric
tends to develop (and become more prominent) with increasing degree of metamorphism Source: Vic DiVenere http://www.columbia.edu/~vjd1/meta_rx.htm Foliation
a common metamorphic fabric in which flat or wavy parallel or sub- parallel planes of minerals are produced by directed pressure
more pronounced with increasing Source: https://naturalhistory.si.edu metamorphic grade
produced by preferred orientation of minerals with naturally platy crystal forms, e.g. mica Source: croninprojects.org  Foliation
from Latin folium, meaning "leaf“
"folio" (e.g. a book) has the same root, e.g. Shakespeare's First Folio
foliage = plant leaves foliated rock  "a pile of leaf-like sheets" Source: blogs.egu.eu Source: Wikipedia CC-BY 3.0 Classification of Metamorphic Rocks gneiss (foliated)  generally separated into two main categories: 1) foliated rocks 2) non-foliated rocks Source: Fletcher, Gibson & Ansdell (2014) Introduction to Physical  foliated rocks classified according to: Geology, Canadian Edition. Wiley. - degree of metamorphism - type of foliation    
   
  


  

 
   

  
  
  quartzite (non-foliated) Common Foliated Rocks shale slate schist gneiss (sedimentary) (metamorphic) (metamorphic) (metamorphic) Source: Vic DiVenere http://www.columbia.edu/~vjd1/meta_rx.htm Slaty Cleavage Source: Left- Roger Kidd (2008) CC BY-SA 2.0; Right- Michael C. Rygel (2007) CC BY-SA 3.0 Non-Foliated Rocks
contain crystals with roughly equidimensional shapes
form under confining pressure - unlike directed pressure  produces foliation
often associated with contact metamorphism Source: geologyin.com  Common Non-Foliated Metamorphic Rocks anthracite (coal) marble metaconglomerate quartzite Sources: Fletcher, Gibson & Ansdell (2014) Introduction to Physical Geology, Canadian Edition. Wiley; geology.com Protolith Rocks & Metamorphic Equivalents
some metamorphic rocks have unqiue protoliths (but others do not) slate quartzite marble metaconglomerate gneiss shale mudstone quartz limestone conglomerate sandstone mudstone granite Types of Metamorphism Source: Grotzinger & Jordan (2014) Understanding Earth, 7th ed. Freeman.
many types of metamorphism
two important types of metamorphism: - regional metamorphism - contact metamorphism Regional Metamorphism
covers large areas of the earth's continental crust
commonly associated with mountain belts where temperature and pressure increase with increasing depth and pressure Source: Karla Panchuk (2018) CC BY 4.0, modified after Steven Earle (2015) CC BY 4.0 Contact Metamorphism
localized, commonly associated with intrusive igneous rocks
intrusion of hot magma heats & metamorphoses surrounding rock with which it comes in contact
affected (metamorphosed) zone is known as a contact aureole
effect dissipates with distance away from intrusion Source: geologyin.com contact aureole Summary – Metamorphic Rocks
metamorphism = change in composition and texture of a rock due to temperature and pressure
protolith = original or parent rock
principal drivers: heat, fluids, time, and pressure
directed pressure  metamorphic fabric, foliation
classification of metamorphic rocks based on foliated or non-foliated - common foliated and non-foliated rocks
two important types of metamorphism: regional and contact  Note: This course will not Suggested Readings cover all of the material in each chapter of the Textbook textbook. These reading recommendations highlight Chapter 10 material relevant to this course.
Introduction
Section 10.1: Controls on metamorphic processes
Section 10.2: Foliation and rock cleavage
Section 10.3: Classification of metamorphic rocks
Section 10.4: Types of metamorphism and where they occur Workbook Chapter 10 - vocabulary and review questions The Rock Cycle
rocks in the earth's crust are continually being transformed in a cyclical way  rock cycle Source: Karla Panchuk (2017) CC BY-SA 4.0  The Rock Cycle
magma in the earth can cool quickly or slowly  extrusive or intrusive igneous rocks
with burial, such igneous rocks can undergo melting to form other igneous rocks, or also become metamorphosed Source: Karla Panchuk (2017) CC BY-SA 4.0  The Rock Cycle
uplift (mountain- building) exposes all rocks to weathering and erosion  sedimentary rocks
with burial, sedimentary rocks can undergo melting to form igneous rocks, or become Source: Karla Panchuk (2017) CC BY-SA 4.0 metamorphosed  Note: This course will not Suggested Readings cover all of the material in each chapter of the Textbook textbook. These reading recommendations highlight Chapter 6 material relevant to this course.
Section 6.1: What is a Rock?
Section 6.2: The Rock Cycle Workbook Chapter 6 - vocabulary and review questions Additional Materials: Rocks & The Rock Cycle Did Curious Rock Formations Inspire the Great Sphinx? - lab experiments and computer modelling now suggest that the erosive power of windblown sand can carve natural landscape formations which may have inspired this iconic monument Origin of the Rocks of Stonehenge - for decades, scientists have wondered from where the various rocks comprising the famous monument of Stonehenge came. Good geological sleuthing (& some luck) finally provided an answer. Additional Materials: Rocks & The Rock Cycle Moon Rocks and Their Origin - an entertaining 10-minute video on the origin of the moon and what we've learned so far from the moon rocks brought back to Earth by NASA's Apollo missions Rocks are so Punny....  Kakabeka Falls near Thunder Bay, Ontario. Source: Joyce McBeth (2008) CC BY 4.0 Topic 4: The Hydrologic Cycle - Surface Water Why is Water Important?
covers ~70% of Earth’s surface
essential to life on Earth
key role in Earth's climate system: heat regulation, distribution
critical to society: used in industry, agriculture, domestic use, etc.
it is a renewable resource Source: NASA, http://visibleearth.nasa.gov/  Water on Earth
97% in oceans, 3% fresh water
only 1% of fresh water is easily accessible (i.e. surface water) - most is tied up in glaciers, groundwater
only ~50% of easily accessible fresh water is in lakes and rivers Source: www.australianenvironmentaleducation.com
Canada has ~6.6% of world's fresh water reserves (ranked 3rd globally) Hydrologic Cycle
water at Earth’s surface can exist in any of the three states of matter: - liquid (water) - solid (ice) - gas (water vapour)
transformations between these: - drives fluxes between reservoirs (e.g. ocean and atmosphere) - are temperature-dependent (e.g. evaporation rates of water are faster at higher temperatures) "flux" = flow rate, rate of transfer between reservoirs Hydrologic Cycle Precipitation runs off Excess falls on land into lakes, streams, Flux in and flux out over as precipitation and oceans… oceans is almost balanced …or infiltrates into soil and rock, where it moves as groundwater Units: 103 km3/year Precipitation
water vapour condenses into droplets
droplets coalesce into larger droplets and fall (as rain or snow)
responsible for majority of fresh water on Earth Photo by CLS Research Office Major Water Reservoirs on Earth
most significant reservoirs: - oceans (97%) - glaciers (2.1%) - groundwater (0.9%) Source: Steven Earle (2015) CC BY 4.0, data from USGS Water Science School (2016) Residence Time
a reservoir: - contains a defined volume of water - water can be added or removed over time
the average length of time that a water molecule will remain in reservoir at or near a steady-state condition  



 
   
 
  

  

  
 
e.g. glass contains 300 mL of water  rate of removal or addition is 30 mL/s, so residence time is 10 s
unit conversion: 1 m3 = 1000 L Major Reservoirs - residence times
essential to consider long-term effects and impact of pollutants entering our water systems Influence of Dams
have many societal benefits  renewable energy supply, source of fresh water, flood protection, water security
also have environmental & societal impacts
dam & reservoir  flooding of large areas; higher evaporation rates; impacts fish migration; can displace human communities Source: Fletcher et al (2014) Intro. to Physical Geology, Wiley.
downstream of dam  river is deprived of sediment, erodes into its bed; river and lands may become less fertile
upstream of dam  river loses energy - sediment deposition and accumulation reduces reservoir volume - can reduce lifespan up to 50%  Fresh Water
small proportion of all water is accessible for human use - ~99% of all liquid water is seawater - much of it is not renewable on human timescales
desalination can produce small amounts of fresh water from sea water  BUT highly energy-intensive and very expensive at an industrial scale
unsustainable use of fresh water risks long-term water availability - excessive extraction for industrial use, domestic use, and irrigation - contamination of surface and groundwater  The majority of surface water in Canada drains to the Arctic, so is not available to most Canadians (85% of population lives within 300 km of U.S. border) a ad an C Data from www.woldwater.org 2011, drawing by Steven Earle Water Use by Sector
in Canada, most water is used for energy generation and industrial purposes Source: Fletcher et al (2014) Intro. to Physical Geology, Wiley.
usage can vary widely from country to country Freshwater Availability
to avoid stressing the water supply, water supply should be at least 10x the average use per day
"water stress"  when a region withdraws 25% or more of its renewable freshwater resources
"water scarcity"  demand for water exceeds available supply Global Water Scarcity
2/3 of the global population (~4 billion people) live under conditions of severe water scarcity at least 1 month of the year
half a billion people in the world face severe water scarcity all year round Data: 1995-2005. Source: Mekonnen et al (2016) Science Advances  "arid" = describes climate Droughts conditions with little to no rain, e.g. in deserts
prolonged shortage in water supply, e.g. precipitation substantially below normal for months to years - streams, wetlands, and lakes dry up - groundwater levels decline
arid regions most susceptible, but can occur in all climates - impacts availability of water for drinking and irrigation
recent / ongoing droughts: - Sahel region of Africa - western USA theconversation.com  Future of Water?
NASA satellite data over 15 years (2002 to 2017) show regions losing (red) or gaining (blue) fresh water
deeply troubling Source: Famiglietti (2019), www. - why? pewtrusts.org
global tropics are getting wetter, but mid-latitude regions getting drier ("wet getting wetter, and dry getting drier")
red hotspots: (1) melting glaciers and ice sheets, (2) places where groundwater being withdrawn (for irrigation) faster than it can be replenished (e.g. Bangladesh, India, China) (3) intensifying drought- stricken areas (e.g. Texas, Brazil, Caspian Sea) Summary – Surface Water
importance of water and water on earth
hydrologic cycle - major reservoirs and fluxes between them
residence time - avg. length of time a water molecule remains
influence of dams
fresh water - global resources, use by sector, availability (stress, scarcity), the future of water  Note: This course will not Suggested Readings cover all of the material in each chapter of the Textbook textbook. These reading recommendations highlight Chapter 14 material relevant to this course.
Introduction
Section 14.1: The hydrological cycle
Section 14.2: Drainage basins
Section 14.3: Stream erosion and deposition Workbook Chapter 14 - vocabulary and review questions Additional Materials: Surface Water Surface Water and Its Treatment - this short video discusses methods of storing surface water, the natural and human activity which can affect water quality, and what can be done to ensure we have a clean and safe source of fresh water.  Source: USGS (1999) Public Domain Topic 5: The Hydrologic Cycle - Groundwater  Water on Earth
only 3% of water on Earth is fresh water
over 2/3 of Earth's fresh water is tied up in glaciers, groundwater
groundwater comprises ~29% of total fresh water supply vs. 1% surface water (i.e. 97% of all available fresh water) Source: www.australianenvironmentaleducation.com
groundwater is a critically important component of our water supply Groundwater Use in Canada Source: https://www.canada.ca/en/env ironment-climate- change/services/water- overview/sources/groundwate r.html#sub5
~30.3% (11.6M) of all Canadians rely on groundwater for every day use
42.8% of all SK residents rely on groundwater Groundwater  any water found beneath the Earth's surface - in caves, rock fractures and crevices, and pore spaces in gravel, sand, and soil
  Source: groundwater.org Source: Maine Geological Survey Hydrologic Cycle Units: 103 km3/year
groundwater and surface water are connected through the hydrologic cycle  groundwater is naturally replenished (recharged) by surface water (precipitation, rivers, streams) when it can infiltrate the soil and rock  Groundwater Terminology Source: Fletcher et al (2014) Intro. to Physical Geology, Wiley.  Source: Fletcher et al (2014) Intro. to Physical Water Table Geology, Wiley.
groundwater systems have two zones: (1) unsaturated zone, and (2) saturated zone
water table  boundary between zones Source: Fletcher et al (2014) Intro. to Physical Geology, Wiley. Surface of Water Table Source: Fletcher et al (2014) Intro. to Physical Geology, Wiley.
shape of water table often mimics surface topography, but comes closer to surface in valleys and intersects surface at streams and lakes
depth of water table also fluctuates with seasons (due to variations in rainfall and amount of surface runoff)  Source: Fletcher et al (2014) Intro. to Physical Aquifer Geology, Wiley.
an underground unit of water- saturated rock or unconsolidated sediment through which groundwater can flow
what makes a good aquifer?  any material that is porous and permeable Source: https://atmos.eoas.fsu.edu/~odom/E SC1000/groundwater/gwater.html  Porosity
fraction of empty space (voids) in a material - unconsolidated sediments: 25 to >50% - sedimentary rocks: 5 to 10% - non-fractured igneous and metamorphic rocks: 100 million people exposed to high concentrations of arsenic in drinking water Source: Jiang et al (2013) CC BY 3.0 Global Groundwater Contamination Map (As) Source: Podgorski & Berg 2020
Canadian maximum acceptable concentration for arsenic in drinking water is 10 ug/L (10 ppb)  Lessons Learned
even with good intentions, things can go horribly wrong if we don’t understand the entire system before we start changing it
we need engineers, geologists, chemists, biologists, social scientists, historians, politicians, etc. – all working together – to put together the puzzle pieces and solve major societal problems
Canadian engineering “iron ring” - remind engineers of primary role towards public safety and an obligation to abide by a high standard of professional conduct Summary – Groundwater
groundwater is a critically important source of drinking water in Canada and globally
groundwater and surface water are connected through the hydrologic cycle
important groundwater terms: water table, aquifer (unconfined, confined, artesian), aquitards, aquicludes
porosity (fraction of empty space (voids) in a material) vs. permeability (ability of a material to allow fluid to flow through it)
groundwater flow  due to differences in potential energy (hydraulic head, hydraulic gradient) Summary – Groundwater
groundwater discharge / recharge and the importance of wetlands
groundwater residence times: days to centuries
groundwater extraction  wells - change groundwater flow pattern - in unconfined aquifers  cone of depression, drawdown, capture zone
management of groundwater resources: (1) overuse (depletion, subsidence, saltwater intrusion), (2) contamination (anthropogenic, natural), e.g. Bangladesh  Note: This course will not Suggested Readings cover all of the material in each chapter of the Textbook [NOTE: section near back of text textbook. These reading recommendations highlight (after Chapter 19). By Steven Earle (2015) material relevant to this Physical Geology, Chapter 14 (Groundwater) course. Chapter 14 (Earle, 2015)  Introduction  Section 14.1:   
 
    Section 14.2:   
   Section 14.3:   
   Section 14.4:   
  Workbook Chapter 14 (Earle, 2015) - vocabulary & review questions Additional Materials: Groundwater What is Groundwater? - this short animation tells the story of groundwater: where it is, where it comes from, and where it goes. What is an Aquifer? - a 3-part series of short videos explains what an aquifer is, the different kinds of aquifers, and how groundwater flows through them, including the use of a physical model to show various features. Additional Materials: Groundwater Groundwater in the News - this Globe & Mail newspaper article illustrates the importance of fresh water and how geoscience (in this case, involving a depleted aquifer) can become deeply embroiled in politics, even up to the level of a U.S. state governor. Good Geology Movie  summary: 
 

 
 

 



  

 
 


 




  

 
  

 







 




 
 
 


   
 

  



https://en.wikipedia.org/wiki/Erin_Brockovich_(film)  
 
 (Based on a true story!)  Source: Bernard Spragg (2007) Public domain Topic 6: Geologic Time Reconstructing Geologic History
geologists reconstruct Earth’s geologic history by studying the rock record - fossils - rock layers and structures - rock chemistry
determining ages within the rock record is key to reconstructing Earth history
relative ages
absolute ages How do geologists measure time?
relative dating is a system of reasoning that is used to determine the relative chronological sequence or order of a series of geologic events (i.e. Source: Fletcher et al (2014) Intro. to Physical Geology, Wiley. with respect to each other)
absolute (radiometric) dating uses the natural decay of radioactive isotopes within minerals to calculate their actual Source: science.howstuffworks.com (absolute) chronological age (age in years) Relative Ages and Geologic Processes
five types of geologic processes used to determine relative ages - intrusion - erosion - deposition - faulting - rock deformation
which processes are evident in this slide?
these processes form the basis of stratigraphy - description and interpretation of the sequence of deposition of rock layers Some Key Principles of Stratigraphy
there are many fundamental principles used to determine relative ages. Four important ones are: 1. Principle of original horizontality 2. Principle of lateral continuity 3. Principle of superposition 4. Principle of cross-cutting Source: San Diego Archeological Center relationships Principles of Stratigraphy Source: Nature Education
Principle of original horizontality - sediments are deposited under the influence of gravity as nearly horizontal layers ("strata")  Principles of Stratigraphy
Principle of original horizontality - subsequent earth movements (deformation) can cause folding or faulting of sedimentary strata Source: Fletcher et al (2014) Intro. to Physical Geology, Wiley.  Principles of Stratigraphy
Principle of lateral continuity - initial layers were laterally continuous, but later separated by erosional features (e.g. Grand Canyon) Source: Fletcher et al (2014) Intro. to Physical Geology, Wiley.  Principles of Stratigraphy
Principle of superposition - each layer of a sedimentary sequence is younger than the one beneath and older than the one above - strata are vertically ordered in time from oldest (at bottom) to youngest (at top) Source: Fletcher et al (2014) Intro. to Physical Geology, Wiley. Practice Exercise (crime sleuthing!) Source: Saskatoon Star-Phoenix (Sat. Nov. 13, 2021) Cassandra Cat claims that a burglar broke into her house through the sliding glass door, stole her designer handbags, and dropped her wallet while fleeing. What evidence and geological principle did Slylock Fox use that suggests this "burglary" was staged? Principles of Stratigraphy
Principle of cross-cutting relationships - geologic features that cut across pre- existing rocks must be younger than the rocks they cut across - such geologic features could be faults or dikes Source: University College Dublin Source: Fletcher et al (2014) Intro. to Physical Geology, Wiley. Source: Ontario Ministry of Northern Development and Mines  Absolute Dating & The Age of the Earth
application of relative-dating techniques in 1700’s implied earth was much older than previously thought (10-100's of millions of years) - fossils - sedimentation rates - cooling of Earth
radiometric dating - based on natural radioactive decay of certain elements (isotopes)
radiometric dating places the age of the earth as ~4.54 Ga - a = "annum" (year) - G = SI prefix "giga" (109) - M = SI prefix "mega" (106) Source: Fletcher et al (2014) Intro. to Physical Geology, Wiley. Review: Atoms and Isotopes
atoms Example: Carbon atom

- composed of nucleus (protons + neutrons) and cloud of electrons
atomic number: - # of protons in an atom - defines the element
mass number: - # of protons plus neutrons in the atom
isotopes - isotopes of an element have the same atomic number (# of protons constant) but different mass number (# of neutrons different), e.g. 12C vs. 14C Isotopes of a Chemical Element
element determined by # of protons, e.g. H has 1 proton
but # of neutrons can vary, e.g. H has 3 isotopes Source: science.howstuffworks.com  Radioactive Decay Change in atomic and mass units: neutron atomic #: -2 mass #: -4 proton atomic #: +1 mass #: 0 atomic #: 0 mass #: 0 Source: http://ib.bioninja.com.au/standard- level/topic-5-evolution-and-biodi/51-evidence- for-evolution/radioactive-dating.html
rad decay of parent  daughter may be a new element
some commonly used geological "clocks": 238U-206Pb, 40K-40Ar, 87Rb-87Sr  Example: Uranium-238 (parent) – Lead-206 (daughter) decay in a rock (not to scale!) Modified after http://vertpaleo.org/ Radiometric Dating
need to determine ratio of radioactive parent isotope to stable daughter isotope
because decay rate is constant, can calculate time since the mineral crystalized
"half-life" (t1/2) - time required for 50% of the original parent atoms have decayed
need to use isotopes with a half- life that is comparable to the rock's age http://earthsci.org/  Example: 238U - 206Pb decay (t1/2 ≈ 4.5 Ga) 

 
  

 
  

 
  (not to scale!) http://vertpaleo.org/ Oldest Earth Materials
oldest rock: Acasta Gneiss - Northwest Territories - oldest known rock outcrop - age of ~4.0 Ga from U-Pb dating of zircon
oldest mineral: 4.4 Ga zircon from Jack Hills, Australia Source: Wikimedia user “Pedroalexandrade” Source: Wilde et al. (2001) Nature 409: 175-178. (2011) CC-BY 3.0 Geological Time Scale
subdivisions - eon, era, period, and epoch
two major eons - Precambrian (4543 - 541 Ma): includes 88% of earth history, earliest life (Archean) - Phanerozoic (541 Ma - present): increased O2 in atmosphere, rapid "explosion" of diverse life
boundaries characterized by significant geologic events, e.g. extinction of the dinosaurs at the Cretaceous-Paleogene boundary Modified from Wikipedia Commons Camels and the Geological Time Scale
"Camels Often Sit Down Mostly Pretty Painfully. Their Joints Creak. Perhaps Early Oiling Might Prevent Permanently Hazardous Ageing."
What does "Ageing" stand for? Modified from Wikipedia Commons Earth History Summary – Geologic Time
determining the ages of rock is essential in reconstructing earth history - relative dating and absolute dating
relative dating: key principles of stratigraphy - original horizontality - superposition - lateral continuity - cross-cutting relationships Summary – Geologic Time
absolute dating - radioactive decay of parent isotope to daughter isotope - age is calculated from ratio of parent / daughter - concept of half-life - Geological Time Scale - subdivisions and boundaries - history of the Earth