DSDP Interface

Select

from the main menu bar. DSDP sites appear on the map, and a table appears below the map:

"Composition" Interface

toggles the composition dialog.

Open one of the subheadings ("minerals" shown), select an item, such as quatrz, and click "load". The item appears in the pull-down in upper-right corner. You may select as many items as you want; they will be added to the pull-down. "load" reads a table with all analyses of the selected compositional item for all samples from all DSDP holes.

closes the item and removes it from the pull-down.

toggles whether all holes are plotted, or only those with analyses of the selected item in the age range given below the slider. If

is un-selected, sites where the item was observed in the age range show up red; if selected, those items are colored with a rainbow color scheme with 0% = blue, and 100% = red. To change the displayed age-range, move the slider by dragging it, pressing the arrow keys, or clicking above or below the knob. By default the age range interval is 10 Ma, the range is 0-200 Ma, and the step is 1 Ma. These parameters can be adjusted by clicking the "Properties" button. If multiple items are loaded, then click the pull-down and press the up or down arrow keys -- the map updates as different items are highlighted.

Example: item = quartz, age interval = 105-65 Ma (Upper Cretaceous)

Demonstrating that windblown sand from the Sahara was significant in the upper Cretaceous.

Age-Depth Models

The composition interface would not be possible without models of age vs depth. These models were developed using a dialog that opens with the

toggle-button on the tool bar above the DSDP table. The graph shows the Geologic ages that are given in the DSDP tables from NGDC (pink boxes), fossil datums from fossil range charts (which may be turned off and on), and the age-depth curve. The graph may be scaled in various ways, and (age. depth) control points may be modified (dragged), added and deleted, to refine the model. The model may be saved. At present, modifying the model has no effect on the model used by GeoMapApp, but in the future, users will be able to select from various age models, including ones they develop themselves, and to submit their models to GeoMapApp so they may be published for others to use.

This interface will be developed further. Additions will include:

Adding more age determinations (e.g., radiometric dates, dated ash layers) to the graph.
Adding panels showing variations of composition, lithology, phisical properties, etc. with depth. These will be added to the right of the age-depth plot, with the same depth offset and scale.
An option to invert the axes, so that properties will be displayed as a function of age.