-U) command from the Windows menu.-O) and locating the ".SAM" file in the
locality folder through the standard Macintosh dialog box. The Sample and
Window menus will now become active. (If your data already displays a little
PaleoMag icon in its icon, then you can double-click on the sample you want to
examine).The normal three windows used in determining least squares directions are the "Zijderveld", "Equal Area", and "Data List" windows. Open these now by selecting them from the Window menu. Note that all these windows are relocatable and resizable in standard Macintosh style using the zoombox, resize box, and menu bar. They can also be removed by clicking the "go-away box" in the upper left corner. A window can be made the active window by either clicking on some part of it or by selecting it from the "Window" menu.
The list window has all the demag steps for the first sample in the file; the data is displayed exactly as in the file. Basically the demag level, geographic declination and inclination, stratigraphic declination and inclination, and intensity are displayed on each line. While this window is active, demag steps can be selected and deselected either by clicking on the step desired or by typing the letter at the left side of each line. A contiguous group of steps can be selected (or deselected) either by clicking down on the first or last step and dragging to the other extreme step or by typing the first step's letter id, then a hyphen ("-"), and then the last step's letter id.
Once a group of steps have been sampled, the Zijder and Equal Area plots can be
updated to include only those steps selected either by clicking on the
appropriate window and making it the active window, or by selecting the "Update
All" (-U) command from the Windows menu.
The Zijderveld and Zijder and Equal Area plots have a couple useful features for your analysis: zoom and point identification. Zooming is accomplished by click-and-dragging over the region of interest; the area that will be zoomed is outlined by a rectangle. When the mouse button is released, the window will refresh and be filled by the zoomed region. The unzoomed view can reestablished by double clicking in the window (not on the window bar) or changing the view (e.g., Geographic to Stratigraphic). Points can be identified by clicking down on them; the demag step will be visible in the upper left corner of the window while the mouse button is held down.
As an alternative to the selection process in the Data List window, you can (once either Equal Area or Zijderveld windows are the active window) select or deselect points by holding down the option key while picking points in these windows. The cursor will become a crosshairs while the option key is down. You can zoom as before, but now clicking on a point will deselect it and the point will become gray (in both Zijder and Equal Area windows, if both are open). Clicking on it a second time will reselect it. Updating all windows, choosing to do a Least Squares Fit, or making another window the active window will cause your selections to become fixed and only the points that remain selected will be displayed or fit. (An older way of doing this does not require holding down the option key--selecting "Select Points" from the Edit menu will make the cursor into the crosshairs and now merely clicking on the point will deselect/select it).
Other aspects of the view in the Zijderveld and Equal Area windows are controlled by selections in the View menu. Data can be projected in either "Geographic" (in-situ) or "Stratigraphic" ("tilt-corrected") coordinates for most plots. For Zijderveld plots, the plot can either be a true Zijderveld plot ("Orthographic") where the vertical axes are Z and north and the horizontal axis is east (or E-W Orthographic, where north-south is shared and north is to the right), or a "hyperbolic" plot where the vertical axes are the same but the horizontal axis is the total horizontal component of the magnetization vector.
After selecting steps as described above, you can fit these points in a least squares sense with a line or plane as described by Kirschvink [1980]. Select "Least Squares..." from the Sample menu; a dialog box prompts you for the type of fit you wish. You may add (or remove) the origin from the points selected by checking (or unchecking) the "Include Origin" box. If the origin is selected, you have the option of fixing the line or plane to the origin. Once the settings are as desired, select "OK" (or hit return). After some minimal amount of time a dialog box will display the results of the fit and a subwindow with all the previous least squares fits from this locality (with the previous fits from this sample highlighted). A three letter code can be typed in to identify this fit (it goes in the demag level field). The vector can be inverted through the origin by pressing the invert button, if desired. The direction will be immediately added to the .LSQ file once the OK button is pressed (or return is hit). If you wish, you can delete old directions at this point. If you enter a 3 letter code identical to that entered previously for the same sample, you will be asked if you wish to overwrite the old fit.
A new sample can be brought up for analysis through any of the commands in the Sample menu: "New Sample...," which brings up a dialog box of all the available samples, or "Next Sample" and "Previous Sample" which bring up the next and previous samples from the one under study, respectively. All windows that are open will be updated and unzoomed, if necessary. You can analyze each sample in succession.
Two additional windows haven't been discussed: J/J0 Plot and Info. The first produces a cumulative and derivative J/J0 plot; the second provides information on the locality and sample currently being analyzed.
Four other plots that combines data from several samples are available for your use: the "Least Squares Equal Area," the "Locality Equal Area," the "Least Squares Strat Plot," and the "Locality Strat Plot." The least squares equal area allows you to plot any combination of the least squares fits you have made by displaying a dialog box with a scrolling windowpane with all the fits displayed. Different fits are selected with the mouse in the same manner as in the Data List window. Statistics can be calculated by making selections from the Statistics menu visible when any of these plots are active. You can display Fisher or elliptical (Bingham or non-parametric) statistics on the plot by checking the appropriate box. If you choose to see the statistics, you can plot any combination of the "True" Fisher confidence cone, the "Hemisphere" Fisher confidence cone, and the elliptical error cone by checking the appropriate boxes (see the description below for more info on these cones and statistics and other options). Once displayed, this plot can only be updated with new information by reselecting it from the Window menu. In most other respects it behaves the same as the Equal Area plot.
The "Locality Equal Area" is similar to the "Least Squares Equal Area" except that you are prompted for the demag steps and samples you wish to plot.
The two strat (stratigraphic level) plots use, as their names suggest, either least squares fits or raw directions from multiple samples in the locality. The numerous options available with this are discussed below; this simply permits plotting of declination, inclination, and intensity versus stratigraphic position.
You can save any of the plots using the "Print..." command in the File menu (provided you have a printer) or the "Copy" command in the Edit menu, which will copy the plot to the clipboard.
The program is completed by executing the "Quit" command from the File menu.
1451 visits from Tue, Apr 21 1998 17:07 to Apr/ 6/02 21:34