Computer lab continued - problem 2.13

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Geology 351 - Geomath
Computer lab continued - problem 2.13
tom.h.wilson tom.wilson_at_mail.wvu.edu
Department of Geology and Geography West Virginia
University Morgantown, WV
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Warm up exercise ??
General comments
Watch out for units e.g., problems 5 (unitless
not kilograms) and in 7, you do have
kilograms. 9. A0 is the age at the depth defined
as 0. It does not have to be the age of the
present-day depositional surface. In this problem
A0 also represents the time it takes to fill up
the lake. Age of sediment at a Depth 0. The
present-day depositional surface may be located
at some arbitrary depth in this case 11.5
meters. 10. You are effectively solving for A0
-11,500 years. It will take 11,500 years to fill
up and that negative sign implies . 11.
implies Past - implies future
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Warm up exercise ??
General comments
19.
In this expression N is the number of earthquakes
of a given magnitude (m) and greater likely to
occur in a given year (units yr-1 or
earthquakes per year). To determine the probable
length of time in years between events with
magnitude m and greater, you need to compute
(1/N) which gives you a result in
years/earthquake. Consider the units.
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17. ysin(5x)
Period 72 degrees or 0.4?
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Evaluate the logs of these two functions
What base do you need to use?
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Age Depth relationships?
Atlantic Margin Seismic Sequences
Chapter 1, 2008, Nittrouer et al.
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Time-depth relationships can often be broken down
into a series of linearly varying age-depth
relationships
Again this data from the Atlantic shelf margin
does not suggest exponential age depth
relationships
Chapter 1, 2008, Nittrouer et al. page 33-34
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In this plot we see slope rate
In this plot we see slope rate-1
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Visit http//curvebank.calstatela.edu/radiodecay/r
adiodecay.htm
Plot of carbon-14 decay rate against age of the
sample in years.
How could you figure the half-life?
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Visit http//curvebank.calstatela.edu/radiodecay/r
adiodecay.htm
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Some other geologic variables also have
exponential dependence on depth, for example.
See Nittrouer et al., 2008
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http//www.otherwise.com/population/exponent.html
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Problem 2.13
Take the natural log - ln
Consider the inverse process take e to the power
of the natural log
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Problem 2.13 deals with exponential decay
formulation. This class of functions is used for
dating a variety of geological materials and is
very familiar to geologists
210Pb dating
22.3 year half life
Stalagmite from cave in France
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Problem 2.13 to do list
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items on the check list

• Hand in problems 2.11 and 2.12 Today
• Have questions ready on 2.13 for Monday
• Read through Chapter 3. Try to work through the
  discussion questions as you read.
• Consider Problems 2.15, 3.10 and 3.11
• No class next Thursday!