Computer lab continued - problem 2.13 Geology 351 - Geomath Computer lab continued - problem 2.13 tom.h.wilson tom.wilson@mail.wvu.edu Department of Geology and Geography West Virginia University Morgantown, WV Tom Wilson, Department of Geology and Geography 1

Warm up exercise ?? General comments Watch out for units: e.g., problems 5 and 7 9. A0 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. The present-day depositional surface may be located at some arbitrary depth: in this case 11.5 meters. Tom Wilson, Department of Geology and Geography

Warm up exercise ?? General comments 13. In this expression N is the number of earthquakes of a given magnitude (m) and greater likely to occur in a given year. To determine the probable length of time in years between events with magnitude m and greater you need to compute (1/N). Consider the units. Tom Wilson, Department of Geology and Geography

y=sin(5x) Tom Wilson, Department of Geology and Geography

Problem 2. 13 deals with exponential decay formulation 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 Tom Wilson, Department of Geology and Geography

Visit http://curvebank.calstatela.edu/radiodecay/radiodecay.htm Plot of carbon-14 decay rate against age of the sample in years. Tom Wilson, Department of Geology and Geography

Visit http://curvebank.calstatela.edu/radiodecay/radiodecay.htm Tom Wilson, Department of Geology and Geography

Some other geologic variables also have exponential dependence on depth, for example. See Nittrouer et al., 2008 Tom Wilson, Department of Geology and Geography

Age – Depth relationships? Atlantic Margin Seismic Sequences Chapter 1, 2008, Nittrouer et al. Tom Wilson, Department of Geology and Geography

Chapter 1, 2008, Nittrouer et al. page 33-34 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 Tom Wilson, Department of Geology and Geography

http://www.otherwise.com/population/exponent.html Tom Wilson, Department of Geology and Geography

Take the natural log - ln Problem 2.13 Take the natural log - ln Consider the inverse process: take e to the power of the natural log Tom Wilson, Department of Geology and Geography

Problem 2.13 – to do list Tom Wilson, Department of Geology and Geography

Due dates Problem 2.13 is due next Monday Read through Chapter 3. Try to work through the discussion questions as you read. Consider Problems 3.10 and 3.11 Tom Wilson, Department of Geology and Geography