Geology 351 - Geomath computer lab tom.h.wilson tom.wilson@mail.wvu.edu Department of Geology and Geography West Virginia University Morgantown, WV

Some more practice (from last Thursday) What did you get? Tom Wilson, Department of Geology and Geography

Computer lab today …. Pick up data set (DepthAge.xls) from Common Drive in folder FittingLabData Just copy the folder to your G or N drive. Tom Wilson, Department of Geology and Geography

Age versus Depth in the North Sea Computer lab… Age versus Depth in the North Sea Lehman and Keigwin undertook one of the first deep sea studies to document changes in sea surface temperature associated with deglaciation. A major change (7o warming) occurs over a 50 year time span.

Computer Lab: North Sea Age-Depth data Paleoclimate When the ocean temperature cools O16 preferentially evaporates Less O18 in the precipitation and more in the oceans

What is 18O See Wikipedia (Sample ratio of 18O to 16O to that of a reference standard-1 )*1000 per mil The increase of ~ from 1.25 to 3, represents and increase in the ratio from about 1.00125 to 1.003 or 1.25 to 3 parts per thousand Plants have a preference for lighter isotopes of carbon and have lower C13/C12 ratios. Fossil fuels from ancient plants have lower C13/C12 ratios. C13/C12 ratios declines dramatically around 1850 with the increased usage of fossil fuels. C14 is unstable and decays; C12 present 98.89%, C13-1.11% C14-0.00000000010%; c14 half life is about 5600 yrs Tom Wilson, Department of Geology and Geography

But rises in organisms living in the colder oceans Thus ice formed during colder periods will have less O18, while the creatures with carbonate skeletal material will contain increased amounts of O18 O18 drops in the ice But rises in organisms living in the colder oceans Drop of del O in the precipitated snow accumulated in the ice cores (-32 to -42) back about 10,000 to 15,000 yrs ago

Age versus Depth in the North Sea O18 from plankton Lehman and Keigwin undertook one of the first deep sea studies to document changes in sea surface temperature associated with deglaciation

Fire up those computers Bring the fitting lab folder over from the common (H:)drive to your N: drive and open DepthAge.xls

Make a plot of the data. Label as appropriate You’ll have an opportunity before you leave to print of a plot

Make screen captures for use in word documents Ctrl C to cut graphs & Ctrl V to paste Print Screen to capture entire monitor view Fn+Alt+Print Screen to capture the active dialog window Ctrl V to paste See handout

Evaluate the logs of these two functions What base do you need to use?

Does the age depth relationship in the North Sea suggest that an exponential age/depth relationship exists in the area? Put it to the test in Excel- If the relationship follows an exponential growth function, then the ln or log of Age should transform the relationship into a linear one.

Problem 2.12 C0 is the initial concentration of the element in the liquid before crystallization began, F is the fraction of liquid remaining and D is a constant (known as the distribution coefficient). Calculate the concentration of an element after 50% crystallization (i.e. F = 0.5) if its initial concentration was 200ppm and D=6.5.

We’re going to take a slightly different approach to the solution of Problem 2.12 that will take advantage of the computer resources and provide a more comprehensive evaluation of the concentration liquid fraction relationship. Rather than solving C for just one value of F let's solve C for a range of Fs extending from 0 to 1 at intervals of 0.05.

F is our independent variable, so for starters, we need to create a column of numbers corresponding to remaining liquid fraction that run from 0 to 1 at intervals of 0.05

Select, Click and Drag Down to Fill

Assign a variable name

In cell B2 enter the formula =CO*A2^D

Homework Format Pb. 2-12 Present your graph. Present hand calculations of the concentration after 50% crystallization. Using your calculated data tables compare the change in concentration from 85% to 75% liquid fraction with that occurring between 55% and 45%

As the result of today’s lab you should know how to do the following: Enter data Graph data Format and style graphical output for presentation Transform exponential functions into linear functions Assign variable names to specific cells in Excel

Review How do you bring in your data? How do you plot your data? How can you change the plot line style (color, thickness, continuous or dashed…)? How can you change the data point display style (marker line style, line color, …)? How do you get back to the Chart Tools? How do you change the chart layout? How do you format gridlines, chart axes? How can you add a chart title? How do you move the graph around in the chart window? What are the three tabs available under Chart Tools?

Consider the following intro review questions (for group discussion) Tom Wilson, Department of Geology and Geography

We’ll continue with the computer lab exercise and have some review For Next Time Finish reading Chapters 1 and 2 (pages 1 through 38) of Waltham We’ll continue with the computer lab exercise and have some review Everyone have the text?

Hand in intro problem set 1-19 Today – Tuesday ... For Thursday Get going on the computer lab and look over problems 2.11 through 2.13 Hand in the two in-class problems before leaving. Hand in intro set 1-19 Continue your reading