If you are one of the few that view this Blog. Please note that the newest manifestation resides at http://geofroth.org.
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If you are one of the few that view this Blog. Please note that the newest manifestation resides at http://geofroth.org.
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?
I have a tendency to map in great detail…even when it is unwarranted or relates to a largely inconsequential stratigraphic situation. This problem is proportional to the quality of the base imagery that I have or the intrigue-level of the units in the field. However, in my quest to lead the effort to develop a surficial geologic map of 10,000 sq. km. of dirt in Clark County in a compressed time frame (see: http://nd2mp.blogspot.com/), I am learning that it is ok not to sweat the details, as long as you explain what comprises the mapped units. One thing that we have learned is that it is essential to develop an agreed-upon minimum map unit area (mmu). That is, the smallest polygon that is mappable at the chosen scale.
Yet another map for 2009…don’t get to excited, though. I won’t
subject you to my rant about how I get surprisingly little credit for
these gargantuan efforts until they are subjected to an external
review…that is for another day. Trust me, it will come. Probably in
mid January.
In any case, this new map includes a snippet of surficial mapping that
I and others did a few years ago in the entirety of Ivanpah Valley,
Nevada…’The Ivanpaviathan‘ with some minor changes.
The big story here is the huge amount of work that the first author
did in creating the bedrock mapping. This is a complicated area to say
the least (heard of the Keystone Thrust and its ilk?). Larry did a
fair amount of new mapping, but really went the extra mile in
compiling diverse scraps and swaths of mapping created over the years
by the other authors. No small task.
Now, about that missing cross section…
Kudos also to Irene for converting what was initially a ‘symphony in mustards’ to this nice map.
See also: http://geofroth.posterous.com/jean-dry-lake-ivanpah-valley-area-nevada
Recall when I went on ad nauseum about my struggles with the Lower
Walker River map as I was trying to document (in part) the struggles
that the lower Walker River has had in dealing with its shrinking
lake? If you missed that fun, experience it here:
http://geofroth.posterous.com/tag/walkerriver
Well, I hardly made a peep about this map…mainly because it
was finished earlier and was out of the ‘buffer’ at the time. But now,
it has reached a comparable state of completion.
It was recently brought to my attention that the graphing tool in ArcGIS could be really useful if you had the right type of data (thanks to ND at UO). Well, I spent most of today trying to refine a longitudinal profile of the Owyhee River from my coveted LiDAR data set, and it occurred to me that I had some useful data.
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.
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:
It is tortured river season in my office. Lately, I have been tackling Nevada’s mighty Walker River and its shrinking terminal lake (new term is terminus lake…but that is a bit soft); and Oregon’s Owyhee River and its travails with lava and landslides; but now I am back on to the Mighty Bill Williams River of Arizona. You know, the Bill Williams River.
Included below is a snippet of the map I am working on. Shown are 6 generations of lines that document major changes in the channel, most since a dam was finished in the late 60s. One day soon, this map will actually make sense, I promise.
Last week I had the chance to explore the upper McKenzie River valley in the Oregon Cascades. My tour guide was a UO PhD student in volcanology. She was showing me the range of interesting lava-water interaction features that characterize the valley. A very cool and unbelievably scenic place.
Hillshade map of the LiDAR data.
The point is that this very conspicuous feature is very mappable, but was overlooked in the development of the 24k map. A bit surprising in that it corresponds to a major ‘peak’ in the forest canopy. I will admit, however, that if you were out there in the rain, you could walk right by it. Certainly makes you wonder what else out there has gone unnoticed by the USGS topographic maps we once relied so heavily upon. Yikes…