Chapter 1: Earth as a Planet. What is Geology? Geology –Scientific study of Earth Physical geology...
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Chapter 1: Earth as a Planet. What is Geology? Geology –Scientific study of Earth Physical geology –Understand processes & materials Historical geology
What is Geology? Geology Scientific study of Earth Physical
geology Understand processes & materials Historical geology
Sequence of geologic events
Slide 3
Using the scientific method Scientific method How scientists
approach problems 1.Observations & data gathering 2.Formulating
hypothesis Hypothesis: plausible, but not proven, explanation for
how something happens 3.Testing hypothesis 4.Formulating theory
Theory: hypothesis tested & supported by observation &
experimentation 5.Formulating law/ theory
Slide 4
The Earth system System concept Break large complex items into
smaller pieces without losing sight of big picture Geosphere Solid
Earth Biosphere All living & once living organisms Atmosphere
Gasses surrounding Earth Hydrosphere All water on Earth All
locations & all states
Slide 5
Cycles and interactions Hydrologic cycle Describes movement of
water Rock cycle Processes that form, modify, transport or break
down rock Tectonic cycle Processes that drive movement &
interactions in lithosphere Lithosphere
Slide 6
Earth in space The solar system Earth is about 4.56 billion
years old Earth is 1of 8 planets orbiting Sun Also includes moons,
asteroids, comets, meteoroids Terrestrial planets Jovian
planets
Slide 7
Earth in space Differentiation: layering of terrestrial planets
based on chemical composition (i.e. density) Crust: outermost
compositional layer Thin, low-density & rocky Mantle: middle
layer Rocky, intermediate density Core: innermost layer High
density & metallic Silicates Mg; some silicates & Fe/Ni
mixed in Solid Fe/Ni Liquid Fe/Ni
Slide 8
What makes Earth unique? Atmosphere Rich in oxygen Hydrosphere
Water as solid, liquid &/or vapor Biosphere Full of living
organisms Regolith Blanket of loose debris covering Earth Soil
Slide 9
What makes Earth unique?
Slide 10
Plate tectonics Movement &interactions of large fragments
of Earths lithosphere (plates) Distribution of volcanoes &
earthquakes Oceanic crust (basalt) Thinner, denser, younger Basalt
Continental crust (granite) Older, thicker, less dense
Uniformitarianism Earth processes today operated similarly
throughout geologic history the present is the key to the past
Slide 11
Why study geology? Earth is our home Depend on Earth for
resources Limited resources require management Earths physical
& chemical processes affect us Need to appreciate our own role
in geologic change
Slide 12
Chapter 3: HOW OLD IS OLD? The Rock Record &Deep Geologic
Times
Slide 13
Relative Age Sequence of past geologic events Age of rock,
fossils, or other geologic feature relative to another feature
Stratigraphy Study of rock layers & processes that form them
Strata Rock layers
Slide 14
Relative Age Principal of original horizontality: water-laid
sediments are deposited in horizontal layers
Slide 15
Relative Age Principle of stratigraphic superposition: each
layer is younger than the layer below it
Slide 16
Relative Age Principle of lateral continuity: sediments
deposited in continuous layers
Slide 17
Relative Age Principle of cross-cutting relationship: layer
must be older than any feature that cuts or disrupts it
Slide 18
Gaps in the record Numerical age Age of rock or geological
feature in years before present Unconformity Substantial gap in
rock sequence; shows absence of part of rock record
Slide 19
Fossils and Correlation Paleontology Study of fossils &
record of ancient life on Earth Use fossils to determine relative
rock ages Principle of faunal & floral succession Stratigraphic
ordering of fossil assemblages Correlation Equate ages of strata
from 2 or more different places
Slide 20
The Geologic Column Geologic time in 1 yearGeologic time in 1
year
Slide 21
Numerical Age & rates of decay Radioactivity Process where
element spontaneously transforms Radioactive decay Parent atoms
Daughter atoms Half life Time needed for 50% of parent atoms to
decay into daughter atoms Radiometric dating Use radioactive
isotopes to determine numerical age of minerals, rocks &
fossils
Slide 22
Rates of decay Examine Figure 3.15 and determine the relative
age of rock layer 4
Slide 23
The Age of Earth Oldest rock: about 4 billion years old Oldest
mineral grain : 4.4 billion years old Meteorites Carbonaceous
chondrites Thought to contain unaltered material from solar system
formation Around 4.56 billion years old
Slide 24
Lab Exercise 2: Maps
Slide 25
Global Positioning System Global navigation satellite system
for determining location on Earths surface Need minimum of 3
satellites visible to determine position on Earths surface
Slide 26
Map Scale Map Scale: relates map distance to Earth distance
Verbal Scale: uses words for relationship 1 inch equals 16 miles
Graphic or Bar Scale: line or bar marked off in graduated distances
0 is not at far left to allow for more precise measurements
Fractional Scale: expressed as fraction or ratio Example: 1/50,000
or 1:50,000 1 unit of measurement on map is equal to 50,000 units
of same measurement on Earth 1 foot = 50,000 feet or 1 cm = 50,000
cm
Slide 27
Calculating Distance with Fractional Scales 1.Measure distance
on map to get measured distance 2.Multiply measured distance by
fractional scale denominator to get ground distance 3.Convert
ground distance to other units Example: If you have a map scale of
1:10,000 and a measured distance of 3.5 inches; complete the
following: _______ feet, _______ miles How? 1.3.5 (10000) = 35000
inches 2.35000 / 12 (1 foot) = 2916.67 feet 3.2916.67 / 5280 (feet
in a mile) = 0.55 miles
Slide 28
USGS Topographic Maps Common scale = 1:24,000 Called 7.5 minute
quadrangle map because map covers 7.5 minutes of both latitude
& longitude Marginal map data gives important info: Map title
Map location Latitude & longitude Map scales Declination arrows
True North (N or *) Magnetic North (MN) Grid North (GN) Map
Symbols
Slide 29
Contour Lines Connect points of equal elevation Contour line
rules pg. 41 of your lab manual Steep slope contour lines close
together Gentle slope contour lines farther apart Contour interval
interval of change between 2 contour lines Index contour usually
every 5 th line is bolder & labeled with value Helps to
calculate contour interval
Slide 30
Contour Map Basics Find the elevations of 2 index contours
Subtract to find elevation change between 2index contours Count the
number of lines you cross when going from 1 index contour to the
other Divide difference in elevation between 2 index contours by #
of lines to find contour interval Example: What is the contour
interval on this map? _____ What is the elevation of Point A? _____
What is the elevation of Point B? _____ A B 20 ft 780 ft 725
ft
Slide 31
Topographic Profiles Shown in plan view Viewed from above Shows
elevation change along a transect (A to B) Creates side view of the
landscape
Slide 32
Lab Exercise 1: Geologic Time
Slide 33
Index Fossils Index fossil: short-lived species tied to
specific time period IDing specific fossils can date rock layers to
specific time period Can be used to point out missing rock
layers
Slide 34
Tree Rings, Varves, & Coral Tree rings Used to find tree
age & ID conditions tree experienced in its lifetime Count tree
rings to find tree age Wide rings = good conditions Narrow rings =
poor conditions Varves Sediment layers that accumulate annually due
to seasonal fluctuations Not frozen = sediment accumulation Frozen
= no sediment accumulation Coral Correlation between # of daily
growth increments & # of days in year Used to determine time
period that coral grew