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I was in the field yesterday doing some mop-up following a field review of a map. While checking a contact I had mapped that was queried by one of the reviewers, I happened upon this blunt assessment of my interpretation rolled up in a desert shrub.

Posted via email from Fresh Geologic Froth


I’ve said it before, and I am sure I will say it again. But this time Google Earth is really making a major difference in my approach to making a geologic map.

My mapping project on the Lower Walker River and the piedmont of the Wassuk Range, NV is taxing my skills as a geologist and as a mapper. It is an extremely complicated setting with active tectonics, catastrophic debris flows, rock avalanches, a wildly fluctuating terminal lake, and a river madly scrambling to keep up with the lake’s rapid, historical decline (50 m in ~100 years). Documenting the ancient, historical, and recent shorelines along the lake is a key component of developing a fairly tight chronology of alluvial fans, abandoned delta lobes, and Quaternary fault activity. However, efficiently digesting all of this information is a far more laborious task with the 24k USGS base maps because the relief in the area is too extreme to accommodate small contour intervals. Air photos are certainly nice, and I do have access to some marginally good LiDAR data and scattered high-precision GPS points, but nothing brings the area into full focus as easily and as efficiently as Google Earth. On this project I have explicitly incorporated GE into my mapping and it has worked extremely well.

GE allows me to quickly and repeatedly pan and zoom my map area and evaluate all of these features of interest. With particular reference to the logistics of making a geologic map, I have used GE extensively to quickly trace mappable shorelines, tag key elevations, and decide how (or whether) to group them for mapping purposes. I have also marked some of the more flagrant fault traces to improve the frame of reference for the map. Of course, I have also linked my geotagged set of field photos so that I can get some clear reminders about key areas I am mapping. The map is being compiled in ArcGIS with good imagery (NAIP) and I can simply transfer my interpretations by visual inspection. Of course, I keep turning to GE to check things out in detail because, somehow, the clarity of the imagery far exceeds what I can force out of the NAIP. Likely I will turn the map of this intriguing area into a kml project. Best area yet for that.

Posted via email from Fresh Geologic Froth

Today, I found out that the Oregon Department of Geology and Mineral Industries (DOGAMI) is releasing LiDAR-based base maps of the Portland area. Some previous discussions I have had with Ian Madin, Chief Geoscientist at DOGAMI have centered on just how much better and more geo-accurately LiDAR data can resolve natural and cultural features. Clearly, he has put this to the test. There are also various ways that the data can be processed to accentuate the natural features as well as the constructed ones, thus producing very nice and accurate base maps.

Here is a link to some examples of their new LIS maps (lidar Imagery Series) to replace USGS topo quads where they have the data:

The image at top shows an example of both the bare earth and the highest hit images of a quarter quad. Of course, I think this is nothing short of revolutionary because I am growing tired of DRGs of 24 and 100k maps. This type of base image is far superior to traditional 24k topographic maps in many ways (maybe not all). Kudos to DOGAMI for setting the bar for us all. I only hope that we can get some of these for Nevada before I retire. Ironically, I already have the data in hand for DOGAMI to make some similar maps for an area in Oregon where I have been working for the past several years.

Posted via email from Fresh Geologic Froth

Ok. So I am not so smart…big surprise. It is digital geoscience for dummies after all, and I am a geologist, not a GIS-geek. At the DMT meeting last week I was able to have several head-to-heads with some well-trained ESRI representatives. I learned more than I can remember now, but the key thing I learned is the value of the network connection/ gis server function in ArcCatalog. Yes, I have always seen it and always ignored it. Whoops. With recent developments at ArcGIS online, you can link your mxd to various streaming sources of data. If you use ArcGIS, you need to check out ArcGIS online.

I started to get a whiff of this when using Topofusion (see previous posts) and, more recently, Global Mapper, because these programs can load imagery in the background of your project when you are online. Anyway, check this out:

The image above shows my Ivanpah Valley, NV megamap (the flood hazard version) at 1:250k with high resolution ortho imagery in the background. Also, check this out:

ESRI provides a decent data set of shaded relief for the globe. This is what southern Nevada looks like. The shaded relief looks considerably better when zoomed out over a larger region and makes a great overview map.

You can also ‘be served’ some pretty decent satellite imagery, as shown below:

So, how does this work? Pretty freaking simple. Create Network Connections in ArcCatalog. You just need to decide if it is an ArcGIS server, an ArcIMS server, or an WMS server. Then you simple add the server data source to your active project much as you would imagery or data hosted on your desktop computer. Of potentially great interest is the fact that you can connect to and choose the data type that you want to add from a long list.

Note: The high resolution imagery available at ArcGIS online is the new color NAIP orthoimagery (I’m pretty sure), so it is completely viable as a geologic mapping supplement. I wish I had known about this long ago. Being self-taught in GIS has its disadvantages. If any of the 4 people out there who may look at this blog know of any other online map services of value to geologists, let me know.

I bet you wonder about how in the world you can track all of the interesting developments in science and mapping on the Internet and then you become so frustrated that you blow the whole thing off. Obviously, my blog is not much help in terms of all of the possibilities, and it is likely that you are not interested in regularly checking on what Dr. Jerque is blathering on about this time. The obvious, obvious, obvious solution to this is to use an RSS reader. What is an RSS reader you ask? Just check this link: RSS explained. In short, it is essentially a program that aggregates updated information from websites and data portals on the Internet. The Internet ‘feeds’ can then be viewed within a simple interface, can be filtered by key words, and sorted thematically. Updated feeds are highlighted so you can see if anything new has shown up. I use a feed reader (yep, Google Reader ) to skim the Internet to find interesting things about digital mapping and the like.

If you install an RSS reader you can quickly subscribe to any site that you visit that includes one of these types of symbols:

You can subscribe to this blog (Geologic Froth) by selecting the previous link or clicking the relevant button in the url bar. That way you can see if I have added anything new without actually going directly to the blog (i.e. determine if it is worth your time to go to the blog at all).

What is most interesting for scientists is that you can subscribe to RSS feeds provided by numerous publishers that show the recent Table of Contents from various journals. The UNR library has collated a list of these (scientific journal rss ), and there are more. Ideally, all journals will eventually do this since it is a very efficient way to inform the scientific community about current research. Once you subscribe to various feeds of interest, you can filter the feeds for key words. You can also subscribe to news feeds that are filtered by topic (e.g., Nevada geology). There are also RSS feeds from the USGS that report recent global seismic activity.

Check the UNR library site for some very useful and concise information about RSS feeds.

Also, I use Google Reader to populate the boxes on the blog that contain links of interest (Fresh Geofroth and Fresh Cartofroth). That is a pretty handy set-up as well. Click ‘Read More’ in one of those boxes and you will learn how to subscribe to the related RSS feed for that particular brand of froth. Cool? yes.

Can you believe what you have been missing? Take 10 minutes to figure it out. You have the time, come on….none of that ‘I am far too busy’ crap.