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No, not because I spend so much time hiking in the desert or because I lugged way too much crap down the South Kaibab Trail last month…not those quads. What is killing me is being a victim of mapping 7.5 minute quads. Mapping 7.5 minute quads is a waste of time. It is efficient only in a clerical sense, not in a scientific sense. Mapping on the basis of 7.5 minute quads amounts to mapping in a rectangular frame with boundaries that are (aside from some amazing coincidence) completely arbitrary with respect to geology.

Obviously, the implied goal of mapping 7.5 minute quads is to allow for a systematic framework for eventually mapping a bunch of officially circumscribed rectangles that cover an entire state or region. The key words here are ‘officially’, eventually’, and ‘rectangular’. Morevover, the concept of mapping quads is so deeply mired in the deeply pre-digital history of the USGS and the history of printing that it has become an ultra-anachronism.

I have been foolish enough to map a patchwork series of quadrangles along the lower Colorado River in an attempt to better understand the river’s geologic history. Each time I move into a new quad, I learn more about that history (or more variations on it) that inform previous maps. Why in the hell I didn’t just try to get funding to map the deposits of interest along the corresponding length of river is beyond me. Eight years later, I am still trying to finish some of those maps (sure, I am a perfectionist, but there are other reasons).

My most ambitious mapping project, the Ivanpah Mega-Map (Ivanpaviathan), is a classic example of how mapping quads can (temporarily) wreck your life. In that case, I stupidly proposed to map the entirety of all of the quads that fell even partly into the boundary of the watershed of interest. WTF? What an idiot. That is how mired I was in the Quad Mapping Model (QMM). I paid and paid dearly for that bit of stupidity.

My job involves mapping a lot of quads in Nevada. My agency has a goal of eventually mapping the entire state. Ha! That is not going to happen at 1:24,000 in my or my kids’ (or their kids’) lifetimes. In fact, this is simply not going to happen ever! Deal with it. Pick the areas that really matter (for whatever reason you like) and map them. Don’t worry, you can still circumscribe the area with a quadrilateral that has easily defineable corner coordinates….



  1. Sounds like Nevada needs to bring back Thomas Dibblee from the world of the no-longer-living to complete the job. He mapped a significant percentage of California at about that scale.


    • High Plains rifter
    • Posted September 8, 2008 at 2:52 PM
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    • Reply

    I assume that your organization gets some of its money through the USGS Statemap program, or at least subscribes to some of the principals implicit in this program. Although the Statemap program, in my opinion, has really energized mapping after a long hiatus during the period of Reagan-Watt scientific medievalism that eclipsed geologic mapping in the 80s, it is not without problems.

    While the program seems to use quad boundaries merely for bookkeeping, this is merely a reflection of the GSs longer term goal to create high-quality 100-k maps (again quad-shaped) for the National Geologic database. As this seems to be an important outcome for them, it would be very difficult to convince their bureaucracy to adopt the more radical idea of topical studies that would not be abandon the *Lorna-Doone_TM* approach to slicing the geologic crust. This limitation has been greatest for the Edmap component for two reasons: 1) the total support is almost too small to even bother with; and 2) quadrilaterals rarely make appropriate boundaries for the topical studies of Masters and Doctoral projects.

    My host organization has fully embraced the quad-boundary model without question. What they have done is to employ teams of mappers (with their respective talents, interests, and biases) to work on quads together. An enormous benefit to my institution is that it also created opportunities to incorporate many unpublished theses and dissertations (after rigorous field checking and filling of any remaining empty map space). Thus, much work that has been sitting the dank intellectual dungeons of library thesis stacks can now be viewed by all. This approach is not without problems. I have supplied the majority of original work on some quads, only to be relegated to the back seat on the authors list merely because I was not the lead compiler. In my case, this had the effect of dis-incentivising my excitement and participation about the program.

    I sympathize with your concerns about boundaries, quad. vs. topical, however, I am not convinced that changing the current system (with respect to Statemap) would be advisable. This would lead to creating many unrelated topical mapping projects without any unifying (but nonetheless imposed) structure. It is quite eye-opening to work with *bedrock* mappers, who tend to have the almost reflexive impulse to apply the old USGS *all dirt = Qal* algorithm to their mapping of unconsolidated material. I consider myself the annoying fly who reminds them that some dirt is worthy of differentiation from the *Qal pit of despair*. Also, when our ultimate benefactors, *the public* sees maps with wildly different boundaries, their overall trust in geologists declines considerably. A proliferation of topical maps would most assuredly lead to these boundary disputes.

    Also, by way of additional anecdote, my whole raison d etre changed as the result of the grid-approach to mapping. After many years in consulting, I was born-again as a dirt mapper (or incompetent-rock geologist, the hypen placement being very important here), but ended up sampling ever-older vintages of dirt in order to fill the holes in the mapping. What I ended up doing was refocusing my work after discovering that the ways of the Olde-Tymers were, in some cases, misleading. If I had only stuck to the youthful dirt, the well-intended, but now clearly wrong ideas of my geologic fore-fathers would have persisted unquestioned. I could pontificate more on this matter more, but I’ve got a paper to write.

    BTW: After many long years of voyeuristically following innumerable blogs, this is my first participation. So I popped my digital cherry in the Geologic Froth, albeit in a wholesomely platonic, non-Larry-Craig sort of way.

    The High Plains rifter

  2. I greatly appreciate the comments! Sometime a rant can rustle the bushes. Thanks for keeping me in line.

    I suspect that mapping California or even Nevada at 1:24k at a meaningful level of detail (even in the Q which is much more cryptic than most would admit) would take a team of dedicated mappers a few generations. Maybe my expectations are too high.

    As for statemap, I have managed to get funding for what amount to irregular shapes but still adhere to a quadrilateral form. That program is essential for sure, but I just don’t think that it needs to emphasize mapping the entire quilt, so to speak. Given input from steering committees and expectations for justifying projects in proposals, I think it is entirely valid to map an area for a specific problem or purpose. Otherwise, I suspect some of the rationales for mapping are stretched a bit.

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