Minimum mappable unit blues 2

For better context, here is a 1:1,000,000 map of Clark County showing where the area in the previous post is located. The map we are trying to complete as Phase 1 of the Nevada Digital Dirt Mapping Project will be approximately 1:150,000. The tiling evident in this image is because the data are divided into the appropriate 100k sheets. For more background on the project, check out the Nevada Digital Dirt Mapping blog. Yes, there is some cross-posting going on...how else could I manage all of this stuff?
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Flash Earth and Geohacks...Who knew? Not me.

Just happened upon a sweet and simple geobrowser called Flash Earth...very smooth and easy to understand. Added bonus for me is that it links to high-res images of my favorite field area that are available only in Yahoo and Bing Maps:

 

Seems my pals at Google still just don't care about SE Oregon. Anyway, I found the site by perusing the details in an exif header in one of my geotagged photos. Was checking that out in Irfan View, a program I was aware of but hadn't tried yet. Turns out, it is well worth a look:

 

 

Which led me to the GeoHack wiki:

 

 

The internets are amazing, no? Totally cool.

 

 

Posted via email from Fresh Geologic Froth

LiDAR-derived contours are useful, too.

Sure, I have gone on and on about the amazing visualizations you can get with some tweaking of LiDAR data; however, it turns out that a pretty basic representation is also quite useful...contours. Yes, contours. Sometimes smaller scale features remain somewhat ambiguous in hillshades or slopeshades, but high-res, short interval contours from the LiDAR data can eliminate most of the ambiguity. In this case, it is a tiny area that I have struggled with on the Owyhee River. Here, a large landslide entered from the north, shoved the river channel to the south, and the river eventually worked its way back to the north to some extent. The array of surficial deposits in the void that comprises the right hand side of the image south of the river record this sequence of events as well as subsequent sedimentation by tributary fans. The contours really highlight the fans, and in conjunction with discernible drainage patterns evident in the LiDAR, it is clear what is fan and what is river, right?
2-m Contours were generated in GlobalMapper and exported as shapefile to view in Arc.
Note, Ian Madin (at DOGAMI) gave me the tip on contours especially as they relate to resolving fan features. He was right...it works!

Posted via email from Fresh Geologic Froth

Extent of lake caused by the Greeley Bar lava dam

I created this lake by generating a contour from the LiDAR dataset at an elevation of 1046 m. GlobalMapper does this in about 1.5 minutes. Then, exported the vector as a shapefile, cut out the parts of the line that occur downstream from the dam, stitch the remaining loose ends, build a poly from the line and there it is.

This lake has an interesting topographic correspondence with the old landslides on the south side of the Hole in the Ground as well as the ancient fan remnants that come in from the north side. Don't forget that much of the topography you can see through the lake didn't exist at the time of the lava dam. The valley floor was probably formed on the Bogus Rim lava which forms the flat-topped features that flank the left and right banks of the river near the eastern end of the lake. The top of the Bogus Rim lava is only about 25 m below the surface of this lake. Thus, the link between this lake and the landslides is dubious as there was nowhere for the landslides to slide.

Posted via email from Fresh Geologic Froth

Plausible extents of landslide-dammed lakes in The Hole in the Ground, Owyhee River, OR

I have developed polygons showing likely extents of lakes related to both lobes of the Doublespring Landslide Complex on the Owyhee River. Using a combination of LiDAR data, ArcGIS, and GlobalMapper in conjunction with the highest plausible geomorphic evidence of fluvial overtopping the following lakes result:
East Spring Landslide: 878 m lake elevation.
West Spring Landslide: 868 m lake elevation.
The correspondence / lack of correspondence of these lakes with various upstream landforms and deposits is surprising.

Posted via email from Fresh Geologic Froth

San Diego State University geology-themed kml files

The Department of Geological Sciences at SDSU is doing a major service for the geological community by providing some excellent geology-themed kml files. The word needs to spread.Go to their site and look for your favorite topic. Who couldn't like this stuff?

http://www.geology.sdsu.edu/localgeology/getour.html

There are an array of useful geology images in addtion to some other, practical datasets. For example, the link below is to a Google Earth file showing the extent, name, and index number of every 7.5 topographic quad in the US. It can be bulky if you leave all of the data turned on, but is useful nonetheless.

http://www.geology.sdsu.edu/localgeology/gekmz/maps_overlays/drg_dem_index/24k.kmz

 

Posted via email from Fresh Geologic Froth

Digital Mapping Nirvana?....Almost

I recently acquired a Wacom Cintiq Interactive Pen Display and it was worth every penny of the $1999 that it cost me. Sure, that sounds like a lot. However, I work on a lot of maps. Without going into detail, I will just note that my commitment to over-commitment is a problem. I truly need to develop ways to more quickly and accurately compile my mapping in a digital form. Nothing (aside from LiDAR, maybe) has streamlined my mapping workflow more than being able to map directly on the surface of a high-resolution monitor. It is one-step beyond my previous advice to run out and get yourself a wacom digitizing tablet because it removes the final level of abstraction that separated your eyes from your work. Since the monitor is quite pricey, it may be a stretch for the average 'joe' (you know who you are). The next best step, the digitizing tablet, is an excellent way to go if that is your limit. Put plainly, you are a pitiable fool for not using either of them. Sorry to say that, but it is true.  Deal with it. I will admit that some of my colleagues that I have goaded into trying the tablet (haven't let anyone touch the monitor yet) have had some issues and, unbelievably, returned to clicking their freaking mice for miles across the virtual landscape. As I have said in the past: can your write your name with your mouse...of course you can't. Why then do you think you can map your favorite intricate contact with one better than you can with a pen? The digitizing tablet / monitor approach is far more efficient. You can program buttons on the pen and the tablet to substitute for frequent commands you use in the program of interest. In the case of the tablet, you can change its inclination to suit your ergonomic needs and can even freely rotate it through a large range of angles to get the perfect attack on the cryptic  contact you think is so important. The Cintiq rocks for geologic mapping. Convince your boss to buy one, or write it into your next geologic mapping proposal. Don't be a slave to a mouse...how embarrassing is that? Disclosure: I am left-handed but also moderately ambidextrous. I use my mouse with my right hand. I use the pen in my left. I use them both when madly mapping in ArcGIS.
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