Geologic Unit Dataset

[hazardgoat]

Description of the desired feature
I would like a geologic unit dataset to be added to pygmt.datasets. After receiving help on the forums for plotting a geologic map, I'd like to contribute what I learned to the example gallery for how to use fig.plot to color polygons by the values in a column. However the PyGMT Contributors Guide says that examples should use data from pygmt.datasets.

Are you willing to help implement and maintain this feature? Yes/No
I am willing to contribute whatever I'm able to bringing this about and maintaining it across new PyGMT releases, though I admit my coding experience is limited.

[welcome]

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[maxrjones]

Thanks for opening this issue. I agree that this would be a helpful example. Do you have a dataset in mind for the example that you would like added to pygmt.datasets? Ideal datasets for examples are relatively small and open source.

[hazardgoat]

@meghanrjones The dataset I had in mind is a geologic map of the US state of California, provided by the California Geological Survey here. As it is a map provided by the state government for the public, I should think that it is freely available for non commercial use. The polygon file itself is ~47.6MB after conversion from .shp to .gmt. I think this would be a good dataset as it is in the vein of what would used in a professional project.

[weiji14]

Similar to GenericMappingTools/gmtserver-admin#100, should we move this issue to https://github.com/GenericMappingTools/gmtserver-admin @meghanrjones? Since this would be of benefit to GMT users as well.

[seisman]

I don't think this geological unit dataset should be added to the GMT server, because this dataset only provides data for a small region (California in the US), while all other GMT datasets have global data coverage.

@hazardgoat's geologic map is a great example and definitely should be added to the gallery, but it would be better if a smaller dataset can be used.

[seisman]

This page (https://mrdata.usgs.gov/geology/state/) lists some geological datasets of US states. Dataset for some states (e.g., Mississippi) is small and should be good to be used in the example.

What do you think?