I just happened to stumble upon an update of a tool to Create Geologic Cross Sections, eXacto Section v. 2.0, that I mentioned in July. Jennifer Carrell at the Illinois Geological Survey wrote this tool. The latest update is from December 8, 2010 and can be downloaded at ESRI’s ArcGIS Resource Center. Our office has used previous versions and finds in very useful in creating cross-sections. I have not tried this latest update.
The Arizona Geological Survey has a great looking site with some good information. They have a publication list that can either be downloaded or ordered and are making pdf versions of their recent publications available online.
I was going to note that there was no download-able data available until Google told me that they in fact had a WMS/WFS available online. The WMS is a great looking map, I have not gotten the WFS to work, however–probably more due to my abilities than the service.
They are also temporarily hosting a surficial geology map of Clark County, Nevada.
The Michigan Office of Geological Survey appears to have pdf versions of all the documents in their Digital Geological Library available for download. The transcripts of some early (beginning in 1871) field notes are a fun inclusion in the available archives.
Actual GIS data was a bit hard to find although I found both bedrock geology and quarternary geology available from the state Geographic Data Library in shapefile format. I also found oil and gas well data but did not download it.
The data carried minimal attribution, one interesting thing I found in the bedrock data was the red, green, blue values apparently used for each polygon.
One thing to be aware of is that the shapefiles do not come with a prj file which could be a problem. Michigan has their own defined coordinate system called Michigan GeoRef. This coordinate system defines the entire state into a single zone instead of multiple zones like the USGS’ stateplane system does. This is nice to work with UNLESS it comes undocumented as I found out while doing some consulting work in Au Train, Michigan a decade ago–I was able to finally find something online about it around 2 am one morning but I think I still have scars from the head-pounding that occurred that night.
ESRI, however, makes it easy to deal with this data–they include the specifications for Michigan GeoRef in inventory of predefined coordinate systems that ships with ArcGIS. If you define the projection on each shapefile, it will then load automatically in real-world coordinates. To define the projection on a shapefile, right-click on it in ArcCatalog and select “Properties…”. Select “XY Coordinate System” on the Shapefile Properties dialog. Hit the “Select” button and navigate to Projected Coordinate Systems-State Sytems-NAD 1983 Michigan GeoRef (Meters).prj. Hit the “Add” button and then the “Apply” button. Repeat for any other shapefiles you download.
One item I found out about ArcGIS while doing this is that if you change the projection on a shapefile, it will recognize that change the next time you use that data. I originally set the units to be feet on the data so it did not load in the proper real-world location. I saved my ArcMap document, quit out, and corrected the problem. When I re-opened the document, Michigan had migrated back to where we are used to seeing it. This contrasts with how ArcView 3.x use to handle raster data, you had to actually remove the layer from your view and re-load it to recognize the change in spatial references.
The Wisconsin Geological and Natural History Survey has a well organized, appealing website. Their data is easy to find although there is not much GIS data available.
Although because I am more interested in sample data sets than anything, the GIS data they do have–statewide geologic map; pleistocene geology, precambrian geology, quaternary geology, (surficial?) geology and bedrock geology for various counties–may actually be a great reference. Other than the statewide geologic map, the data is available on a per-publication basis.
Some other data is available in the open-file reports.
They also have a well contructor’s reports CD available for purchase, albeit only scanned images of the wells and a very simple database.
Other .pdfs are also available of various state-wide maps and for various open-file reports.
I found some interesting things while reviewing the data I downloaded.
- There is minimal attribution on the data–enough to symbolize it.
- Dip & Strike triangles are captured as points with attribution of the horizontal azimuth and inclination.
- One item I found odd at first but quickly grew to appreciate is that they provide a georeferenced .sid of each plate. This allows you to directly compare the digital data to the final cartographic product. Think this may be a keeper of an idea.
Their GIS data is minimally attributed for the most part, their public wells data set did have a more robust attribution scheme. One cool feature I found in the wells data is that they provide a hyper-link for many features to an on-line site record. Found both shapefiles and file geodatabases in the samples I downloaded.
More interestingly, I opened up their Bedrock Geological Map and noticed something odd to me. See the bulls-eye just NW of center? That, even to a non-geologist like me, does not look too geologic.
Turns out it is related to a meteorite impact known as the Manson Crater, once thought to be The Dinosaur Killer until it was determined to be too old.
In the last couple months, I’ve had a bit of an eye-opening about Geography. People actually trained in geography may implicitly understand this but I, with my Accounting degree, have spent the last 16 years “doing” GIS without realizing the foundation of geography–geology. I picked up enough geography to understand some of the inter-relationships between people and the lands they live on.
But what I didn’t pick up on was how the lands we live on are formed. Maybe it is a moot point–how physical geography is arrived at doesn’t matter, just how we react to it. But, and now working for a Geological Survey, I better have this opinion, a better understanding of what our geology is and how it was formed really does form the foundation for the geography.
Two examples. First, in talking with my new supervisor, he was talking about how, because of the geology in the southeast part of the state, they have a lot of water quality issues–the water tends to have sulfur in it. With the recent interest in alternative energy sources, and in this case ethanol plants water quality is a concern when deciding where to build the plants because they require a considerable amount of water. For some reason there have been plants placed in this part of the state and they are having some problems finding sufficient water.
The second, and I’m not sure that this is actually fact or just a theory but it is an interesting idea, was something I read in Malcolm Gladwell’s book Outliers. In the book, it was suggested that there was an almost epidemic of feuds, a la Hatfield-McCoy, in part of the US largely due to the geology of a portion of the country. The areas that relied on a herding economy developed a clannish “code of honor” that led to these long-term feuds. While I understood that physical geography effects human behavior I hadn’t taken the mental step to link geology to physical geography.
Pretty silly and probably obvious oversight.
And to think, I use to think the “G” in GIS should really stand for Geometry. Humph!