Geology 351- Mathematics for Geologists
Keep Track of your Grade
It’s simple math to estimate your current class grade. Dr. Behling’s segment counts for 1/3rd of the semester grade and my section counts 2/3rds of the total. I also have an extra credit term report option that you can take advantage of which can add 5 points to the total grade in my segment (3.33 points to the total course grade). To make it easy for you to gauge where your headed or to determine what kind of a grade you’ll need to get the course grade you want, I’ve written a little windows program to help you work up the totals for you.
To get a copy of this program double-click on the network neighborhood icon in your windows display and then double-click on Wilson.
You’ll see one folder titled shared. Double click on that and you’ll see several additional folders and files. Click on Geomath and there you’ll see a single file titled GeoMathGrade.exe. Copy that file to your G:\Drive.
We will go through this in class.
Once you get the program copied to your G:\Drive. Double click the exe file and the following program window should appear.
Program operation is pretty straightforward. Just enter current or speculated grades into the grade boxes, select one of the two grade-type options, and then click on the Compute my Grade button. Your grade will appear on the screen as illustrated below.
You can play around with different grade combinations to see what it will take to reach your goal. We’ll run through this a couple times.
Internet resources for Waltham’s text Mathematics for Geologists
Bring up your internet browser (Netscape or Microsoft Explorer) and enter the following address into the URL location list box. The following screen will appear –
When you click on the Links button, the following screen will appear.
Click on the bottom item in the internal links list titled Mathematics: a simple tool for geologists another page will appear containing a brief description of the text, with a note that the 2nd edition contains references to downloadable EXCEL ffiles, and that if you wish to download them - “ … to your computer, simply press here.
Go ahead and press on here and the following list will appear.
Click on the file Quadrat.xls …
And the following window will appear.
Note that you can open it or save it to disk. Select the save to disk option and then click OK.
Save it to your G:\Drive
(to be illustrated in class)
Now bring up EXCEL by clicking on the windows Start button down in the lower left corner of the screen. This should bring up a pop-up menu with a list of programs. On that list you should see a big X labeled Microsoft Excel. Click on that to start EXCEL.
From the EXCEL menu bar click on File and then on Open. From the Open dialogue box, navigate to the G:\drive and then open Quadrat.xls.
The following window should appear.
We’ll spend a little time going over all this in class, and there will be plenty of opportunities to gain experience working with Excel and another scientific analysis software called PsiPlot. Remember that one of our main objectives for the semester is to develop some basic computer problem solving skills that will be of use to you on the job as well as in other Geology courses.
Geology 351 - Geomath
Computer Lab - Introduction to PSI-Plot and Problem assignment
PSI-Plot is a technical plotting and data processing program. Many of you may already be familiar with EXCEL which is similar in some respects to PsiPlot. The following instructions are meant to take you step-by-step through the generation and plotting of a data set. You will also learn how to fit straight lines and polynomials of higher order to specific data sets. We will also deal with log-log formatting of plots. Problems related to material covered in class last time will be assigned today and you are expected to use PsiPlot as a tool to help you solve these problems.
GETTING INTO PSI-PLOT
PSI-Plot runs in the PC windows environment. Double click on the PSI-Plot icon. When the PSI-Plot window opens up, click on FILE then on NEW and then on Sheet. A spreadsheet or window containing empty rows and columns will appear on the screen.
Our first task is to enter some data for analysis. The following data are taken from Chapter 2 of Waltham's text (page 37, problem 2.11). The problem states -
2.11 The following data were taken from the Troll 3.1 well in the Norwegian North Sea.
(Enter the following depth, age data in columns C1 and C2, respectively.)
C1 / C219.75 / 1490
407 / 10510
545 / 11160
825 / 11730
1158 / 12410
1454 / 12585
2060 / 13445
2263 / 14685
Data taken from Lehman, S., and Keigwin, L., (1992), Sudden changes in North Atlantic circulation during the last deglaciation, Nature, 386, 757-762.
Rename both column by clicking on the column title, and typing in Depth (in column 1) and hitting return and then clicking on the second column title and typing in Age and hitting return again.
Your screen should look like this when finished -
NOTES
GRAPHING AND PLOTTING!
Let’s plot up this series of numbers.
Click on PLOT (a menu drops down)
Click on 2D Curve > (menu opens to right)
Click on XY Lines (2D XY-Lines window opens up)
Note that in this case, X> defaults to a, and Y> to E.
Click on ADD CURVE>, then OK
Pat yourself on the back you are on your way to mastery.
NOTES
ODDS and ENDS -
Move the mouse arrow down into the plot area and Click it in an empty area of the plot.
Note that the plot will be highlighted (eg. square dots appear on the plot margins). You can resize the plot by clicking on the highlighted edge or corner points. You can move the plot around by clicking within the bounds of the plot and dragging it to a desired location. Try it.
To close your plot, move the mouse over to the upper left corner and
click on the X sign. Then
click on CLOSE, then
click on NO (you don’t want to save it). This will return you to your spreadsheet.
NOTES! Notes!
Learned one - now do one. Here are some things to try on your own.
PLOT
2D CURVE
XYLINES
- but, this time click on STYLE> and select another symbol.
Click on COLOR> and select another color.
Double click on the little window next to Symbol Size:, and enter0 (only the line will appear).
Don’t forget to click on ADD CURVE, then OK.
Note that the plots default to a landscape layout. Let’s change that to portrait.
Click on FILE (Menu drops down - note variety of selections. Experiment later.)
Click on Printer Setup.
Click on Portrait, then
Click on OK
Resize the graph to fit in the upper third of the sheet.
Double click on the graph title Sheet Untitled.
Sheet untitled will be highlighted in blue. You can type in any title you’d like. Do so now, and also note the other options in this window, including Font, Size, Italic, etc.
Click on OK.
You can change axis labels the same way.
Note the tool box off to the right.
Click on abc
Bring the cross hairs over to a suitable place on your graph.
Hold down the left mouse button and drag open a rectangular box to place a label.
When you release the left mouse button, a text format window will open up. You can enter a relevant label as you did for the title and axes above.
Click on OK when done.
NOTES:
Click on your label, and move it around.
Click on an open space within the graph. Note that the graph is highlighted. Now
Click on the label you entered above. Note that the graph remains highlighted.
You will have to push it back.
Go to VIEW (a window drops down).
Click on Push Back.
Now click on your label. Voila!
More on Problem 2.11: From the graph and data listing (i) estimate the sedimentation rate for the last 10000 years, (ii) the sedimentation rate for the preceding 5000 years, and (iii) the time since sedimentation ceased.
Compute from data points with depths extending from 19.75cm to 407 cm and ages of 1490years to 10510 years. This yields .
GENERATING A LOG-LOG PLOT-
Remember that in the Chapter 2 discussions (see pages 29-31) porosity () is noted to vary in proportion to 0exp(-z/). Water is being squeezed out of the sediments and changes of porosity decrease exponentially with increased depth. We might guess that the log of depth might vary linearly with porosity.
Let's check it out.
Double Click on the x axis (Depth axis in this case). An Axis Format window will open up. Go over to the axis mode, click on the down arrow, and change linear norm to log (decimal). Click on NaturalRange in the middle of the window, but change the minimum value to 10 and then click on OK. Note that the Depth axis will be rescaled into logarithmic intervals.
Does your plot look more like a straight line?
This has just been a basic run through on some of the options available through PLOT.
MORE NOTES?
We will return for more later in this DEMO. But the best way to learn will be to experiment.
Once you're finished you can save your data. I suggest that you save your data in the g:drive.
Take Notes on how to do this!
Click on File - Save As
And select the g:drive from the saving plot window.
Give your file a name you will remember like problem2-11. I suggest using a - or an underscore _ instead of a . since the computer will consider words separated by periods as extensions.
When you save on the g:drive you can go to another computer and access your data. If you save on the c:drive (the default save drive) you will only be able to access your data from that machine.
Plot files have a PGW extension (G for Graphics), while data files have a PDW extension (D for Data).
Save your plot, close the plot window (click on the x in the upper corner of your plot window -NOT THE PSIPLOT WINDOW!!
You should now be back in your spreadsheet. Also save it also and close.
MORE NOTES
Problem 2.12
As crystals settle out of magmas, element concentrations, C, in the remaining liquid change according to the equation
where 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.
Let's take a different approach to the solution of Problem 2.12. 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.
This will give us a total of 21 computations of C. Sounds like a lot of work, but with the help of PsiPlot, we can probably do all that in the time it would take you to do one computation by hand.
First -
Open up a blank spreadsheet. Click on the short-cut button just below the File option (see right)
This will open up a brand new spreadsheet.
Now we want to generate a column of numbers corresponding to F (the fraction of liquid remaining ) that range from 0 to 1 in increments of 0.05. To do this, click on Data , Fill Selection and then Algebraic (see illustration at right).
Another window will pop up (see right). We are placing values of F in column 1. The values will occupy cells 1 through 21, The first cell has a value F = 0 and each consecutive cell will have a value F incremented by 0.05
Rename that column F so that your spread sheet looks like that right
Now go to Math Transform (right) and enter the equation
C=200*F^5.5
* represents the multiplication operator
^ represents the exponentiation or power operator
The equation says
.
Hit the enter key and the column next to F will be filled with values and labeled C as shown at right.
How does concentration (C) vary with liquid fraction (F)?
Remember how to Generate a plot?
Complete Problems 2.11 and 2.12 and hand in next Tuesday.