Fresh New Insights from the LiDAR

Hey y'all. I spent three days at the AASG Annual meeting in Park City, UT this week. Gave a presentation in front of approx 30 versions of my boss about 'Simple Digital Geology for Typical Analog Geologists'...went very well and was a lot of fun. Had a chance to talk with Ian Madin of DOGAMI about LiDAR visualization. In 2 seconds he convinced me that using a combination of slope shading and elevation color ramping produces the best results in almost every setting. I do recall that, on our last trip, Natalia asked me why I didn't use this method on the maps I handed out. Good question. Now I do.

Here are some images of a familiar area:

The slope-shading method looks a bit less 'real' but provides an amazing enhancement of slope contrasts that reflect important contact relations. Try it out on the data yourself and you will be amazed at the new array of relations that will jump out at you. For example, look at the young landslide nested in a larger slide along the Saddle Butte lava flow in the lower left corner. Pretty obvious now, no? Probably blocked the channel. During field camp, I found one of these in the Artillery Rim complex that is nested in the older slide complex. It too flanks a notably narrow reach of the river and may be associated with a young blockage.

Yes. Some additional map details will be added soon.

Also, while at the meeting I spoke with Vicki McConnell (State Geologist of Oregon) about publishing the map. She is all for it as long as I (we) can help defray the cost of production. I suspect the NSF grant can help cover this. I will do the lion's share of the work, so shouldn't be too much.

The Penultimate List of Map Units

It is crunch time on the map. I have so many other maps to work on that I need to begin seriously riding the asymptote to the completion of this one. After many years of solo and collective field observations and various consultations, arguments, and friendly exchanges with most of the Yeehows, I have settled on this list. If you have grave concerns please, please, oh please let me know sooner rather than later. I will throw the correlation diagram up soon.

Hillslope Deposits<o:p></o:p>

Qcf Undivided colluvium and alluvial fan deposits, Holocene to Pleistocene<o:p></o:p>

Qc Colluvium, undivided, Holocene to Pleistocene<o:p></o:p>

Eolian Deposits

Qe Eolian sediments, Holocene to late Pleistocene(?)<o:p></o:p>

<o:p></o:p>

Deposits of the Owyhee River<o:p></o:p>

Qra Active channel and floodplain alluvium, Recent to late Holocene<o:p></o:p>

Qry Young fluvial sediments, Holocene<o:p></o:p>

Qrty Young floodplain terraces, Holocene<o:p></o:p>

Qrt1-n Fluvial terrace gravels, Pleistocene (numbered in local depositional order where appropriate)<o:p></o:p>

Qrg Fluvial gravel, undivided, Pleistocene<o:p></o:p>

Qgb Fluvial boulder bars, Pleistocene<o:p></o:p>

Qgw Fluvial gravel of West Crater lava, late Pleistocene<o:p></o:p>

Qrgo Older fluvial gravel, Pleistocene<o:p></o:p>

Qgbr Fluvial gravels of Bogus Rim lava, early Pleistocene<o:p></o:p>

QTgl Ancient, inter-lava flow fluvial gravel, early Pleistocene to Pliocene<o:p></o:p>

QTga Fluvial gravel of Artillery rim, early Pleistocene to Pliocene(?)<o:p></o:p>

<o:p> </o:p>

Lacustrine deposits of the Owyhee River corridor<o:p></o:p>

Qfl Fluvio-lacustrine sediments, undivided, late Pleistocene<o:p></o:p>

Qflw Fluvio-lacustrine sediments of West Crater lava dam, late Pleistocene<o:p></o:p>

Qfls Fluvio-lacustrine sediments of Saddle Butte lava dam, late Pleistocene<o:p></o:p>

QTfa Fluvio-lacustrine sediments of Artillery Rim, early Pleistocene to Pliocene<o:p></o:p>

Landslide Deposits<o:p></o:p>

Qls Landslide deposits, undivided, Holocene to early(?) Pleistocene

Qlsy Young landslide deposits, Holocene to late Pleistocene<o:p></o:p>

Qlsby Young landslide deposits composed dominantly of coarse basalt breccia, Holocene to late Pleistocene<o:p></o:p>

Qlsi Intermediate age landslide deposits, late Pleistocene<o:p></o:p>

Qlso Old landslide deposits, middle to early (?) Pleistocene<o:p></o:p>

Alluvium of Owyhee River tributaries and local drainages<o:p></o:p>

Qa Alluvium of tributary washes and alluvial fans, undivided, Holocene to Pleistocene<o:p></o:p>

Qas Alluvium and related sediments of active springs, Holocene to late Pleistocene<o:p></o:p>

Qad Alluvium of closed depressions and sags, Holocene to late Pleistocene<o:p></o:p>

Qay Young alluvium of tributary washes and alluvial fans, Recent to Holocene

Qai Intermediate age alluvium of tributary washes and alluvial fans, late Pleistocene<o:p></o:p>

Qao Old alluvium of tributary washes and alluvial fans, middle to early Pleistocene<o:p></o:p>

QTa Ancient alluvium of tributary washes and alluvial fans, early Pleistocene to Pliocene<o:p></o:p>

Basalt lavas of the Owyhee River corridor and surrounding areas<o:p></o:p>

Qbcp Basalt of Coffee Pot Crater, Holocene*<o:p></o:p>

Qbrb Basalt of Rocky Butte, Holocene (?) to late Pleistocene*<o:p></o:p>

Qbw Basalt of West Crater, Pleistocene<o:p></o:p>

Qbs Basalt of Saddle Butte<o:p></o:p>

Qbsy Younger basalt of Saddle Butte<o:p></o:p>

Qbso Older basalt of Saddle Butte<o:p></o:p>

Qbc Basalt of Clarks Butte<o:p></o:p>

Qbg Basalt of Greely bar, early Pleistocene<o:p></o:p>

Qbr Basalt of Bogus Rim, early Pleistocene<o:p></o:p>

QTbc Basalt of Bogus cliffs, early Pleistocene to Pliocene<o:p></o:p>

QTb Basalt, undivided, early Pleistocene to Pliocene<o:p></o:p>

Tb Undivided basalt lavas, Pliocene to Miocene (?)<o:p></o:p>

Tbs Undivided basalt lavas and interbedded sediments, Miocene to Pliocene<o:p></o:p>

*These lavas only on regional map, not in river corridor

Rhyolite lavas and sedimentary rocks<o:p></o:p>

Tsv Interbedded volcanic, volcaniclastic, and other sedimentary rocks, Miocene<o:p style="font-weight: bold;"></o:p>

Tr Undifferentiated rhyolite lavas, Miocene<o:p></o:p>

Sorry Yeehows, Our Secret is Out

The hydrograph above effectively encapsulates the ambient conditions of field camp. The overall wetness was pretty freaking shocking.

The field camp experiment is over. It was a muddy success. The region was (and still may be) under the influence of a persistent cutoff low pressure system that delivered record amounts of rainfall. It is true that the roads on the rim become somewhat challenging when they get wet, but we did manage to get seven vehicles all the way in and out to the Artillery Rim camp site (eventually). The first night at Rome launch, it rained nearly 1.5 inches. A record for Rome. It was truly disheartening. While lamenting my plight at the Rome Cafe very early on Saturday, the woman in charge at the time offered up access to the Grange building in Arock for us to use while we waited out the rain. Once in Arock, we were given access to the Arock School by an extremely gracious host. The school was a perfect fit for us...hot water, bathrooms, class rooms with high-speed internet, a playground, etc.

While at the school waiting out the rain, I gave a marathon lecture (with playground breaks) about the study area, the Quaternary, surficial geologic mapping, and of course provided various demonstrations about geotagging photos, how the gigapan robot works, how I make a map in ArcGIS, and how the magic pen works.

Thankfully, Duane and Caitlin were also there. Duane gave a lecture about the history of paleomagnetism and described how it works in the case of correlating basalt units in the field area.

Caitlin gave a lecture about her project. That night it rained like hell and we enjoyed watching a major thunderstorm plow through Arock. All the more enjoyable because we had a dry place to sleep.

The next day, we had a foreshortened tour of the field area (mud concerns) and made it to the Coffee Pot lava field and the vent by way of the Rockhouse Coffee Shop...all great places to take students.

The road to Birch Creek was in good shape so we peered over the rim. The students were moderately amazed because all they had seen of the river so far was the boring reach at Rome. We then headed out through JV and actually made it to Artillery Rim with only minor mud delays.

Once at the camp site, we approached the rim on foot as a group, and it was the perfect field camp moment. Everyone was awestruck by the view from there.

What then ensued were two perfect field days in the Artillery Rim landslide complex...full of ticks and snakes (lots of snakes), but the weather was perfect. The students had never faced such a complex array of landforms and deposits. Rest assured they have newfound respect for rivers, canyons, and Quaternary geology (and rattlesnakes).

The field camp mascot...saw 9 or 10 rattlesnakes in two days.

Here's an idea. Bring the girls from the Mackay School of Mines Mining Team into the field to dig for you. Next year, the augering competition. In less than 15 minutes they created the best exposure of the Qfl that any of us has ever seen.

The last day ended with an all night soaking rain, and we (the TAs, the cook, and I) were concerned that we may be stuck for a day. It was extremely wet that morning. But, alas, Duane (who proved various times on the trip that his last name is no fluke) and his field assistant Nicole showed up at our camp around 8 AM proving that the roads were viable. As we then rapidly started to take the camp down, it started to rain very hard and things were horribly wet. As we pulled out of the camp, there was a lot of water running down the rocky road past the gate. The rim roads were muddy as hell in the immediate area and one van got mired. It was a relatively easy extraction and we were again on our way through the mud. As we approached the (once-named) veneers of dreaded rim gravel, we changed the name to the sanctified rim gravel. The roads were fine and we proceeded out of the field with no incident.

Looks like my UNR field camp session will hit the Owyhee every year. It remains an amazing place worthy of sharing.

A beautiful evening looking north over the Artillery Rim landslide complex. Worth the trip.

Trip re-cap: The Boulders

This year's group trip to the Owyhee was a great success. I, with much help from everyone, filled in some gaps in the map and the stratigraphy; we all found some new stuff; explored some new areas; acquired valuable field data; and met some very cool people. I am madly compiling the gigpans I took and just remembered that I needed to reduce the GPS data for the boulder measurements. Just got that done. Here are some screen shots:

Bunny's Bar:

Artillery bar:

Look at each and note the very high correspondence between the two types of data--LiDAR and High-Precision GPS. It is a whole new world. Don't fall off.

Incision of Hell's Canyon

Hi again,

If you are not up on the evolution of the Western Snake River Plain (WSRP) and the timing of the cutting of Hell's Canyon in relation to the Owyhee intra-canyon lava flows then consider reading a paper by BSU Emeritus geomorphology professor Spencer Wood and his colleague Drew Clemens, "Geologic and Tectonic history of the Western Snake River Plain, Idaho and Oregon" Find it at:
http://earth.boisestate.edu/home/swood/WOODCLEM-2002.PDF
Among other things, the paper discusses where and when Lake Idaho existed and how and when Hell's Canyon was cut. It refers to work done by Kurt Otherberg, who Jim had mentioned before in the context of Hell's Canyon.
-Spud

Paleoclimate of northern Great Basin and Owyhee area

Hi folks,Two years ago I asked Peter Wigand for some direction insearching for papers that might help us understand thepaleoclimate (and therefore perhaps river discharge andstream power) of the Owyhee River basin.  He replied tome but I never was able to track down all the papers hesuggested.  I am providing his suggestions here in thehopes that we can improve our understanding of what theOwyhee River might have looked like during the existenceof the lava dams.  He said to start with the first onewhich had an extensive bibliography that wouldlead to some of the others.-SpudWigand, P. E. and D. Rhode. 2002. Great BasinVegetation History and Aquatic Systems: The Last150,000 years. Pp. 309-367. In Hershler, R., D. B.Madsen and D. R. Currey (eds.), Great Basin AquaticSystems History. Smithsonian Contributions to EarthSciences 33. Smithsonian Institution Press,Washington, D.C.Mladen Zic, Robert M. Negrini, Peter E. Wigand. 2002.Evidence of synchronous climate change across thenorthern hemisphere between the north Atlantic and thenorthwestern Great Basin, USA. Geology 30(7):635-638.Cohen, A. S., M. Palacios, R. M. Negrini, P. E.Wigand, and D. B. Erbes. 2000. A paleoclimate recordfor the past 250,000 years from Summer Lake, Oregon,U.S.A.: II. Sedimentology, paleontology, andgeochemistry. Journal of Paleolimnology 24(2):151-182.Negrini, R. M., D.l B. Erbes, K. Faber, A. M. Herrera,A. P. Roberts, A. S. Cohen, P. E. Wigand, and FranklinF. Foit, Jr. 2000. A paleoclimate record for the past250,000 years from Summer Lake, Oregon, U.S.A.: I.Chronology and magnetic proxies for lake level.Journal of Paleolimnology 24 (2):125-149.Mehringer, P.J., Jr. and P.E. Wigand. 1990. Comparisonof Late Holocene environments from woodrat middens andpollen, Diamond Craters, Oregon. In Martin, P.S., J.Betancourt and T.R. Van Devender (eds.), FossilPackrat Middens: The Last 40,000 Years of BioticChange. University of Arizona Press.Wigand, P.E. 1987. Diamond Pond, Harney County,Oregon: Vegetation history and water table in theeastern Oregon desert. Great Basin Naturalist 47(3):427-458.

OWY-19, river left outcrop of WC between Bogus Falls and Dogleg

Here are two photos--long overdue--that show the contact relations of the WC lava where I collected sample OWY-19. One shows the modern swale that has eroded around the WC lava that filled the paleo-swale. The other photo shows the nature of the contact between WC and lava flows within the Tertiary section: the WC lava sits on top of the Tertiary section there.
-Spud

How old is the Owyhee?

Today, Dr. Froude presented the most basic question: How old is the Owyhee River. I pulled some stuff out of the air in a quick response, and ultimately claimed the river developed between about 5-8 Ma and 1.8 Ma. I decided my response was too quick, and too poorly founded, so I started looking for some of Ninad's data. Turns out that Miami Univ puts all of their dissertations online. Very handy. Thus, I present some of Ninad's dissertation below to serve as a reference point for all of us. By combining his data with our collective field observations, I think we can answer the question. For the sake of completeness, here is my response to Froude's query:

Bogus Rim flow and underlying flows fill a surprisingly deep paleovalley that runs along the alignment of the modern canyon below iron point. Gravels are present at the base of the sequence in a few places (including possibly in the Owyhee Breaks area) and there are erosional intervals preserved between some of the flows. Not sure how well constrained the ages of the lowest flow (the 'lower Bogus lavas') are, but somewhere between 5 and 8 comes to mind (without looking anything up). There was a river flowing north before the Bogus lavas were emplaced. This river created the paleotopography in the Grassy Mountain Rhyolite and sediments before the first big barf of basalt flowed north. Based on the thickness of the Bogus Lavas in the Rinehart Canyon area, there were some deeply incised tributaries flowing into the river.

In terms of field evidence, the biggest influx of gravel occurs in conjunction with the end of the damming event caused by the Bogus Rim flow. I believe that evidence is mounting that a very large lake occupied the area upstream of where the Bogus Rim flow would have created a dam somewhere near Iron Point. Thus, the pre Bogus Rim river was probably a nearly full blown Owyhee. Possibly the full blown river developed in conjunction with surmounting the Bogus Rim dam? That should have been sometime after about 1.8 Ma. I recently collected a tephra from the lake sediments that I postulate were deposited into a Bogus Rim dammed lake. Dating that may be of some value.

Here is the geochronology from our area as reported by Ninad Bondre:

Here is a nifty map that places these data in a better context:

Also, Ninad's thesis includes a handy little geologic map:

Some thoughts:

Despite the geochronology, I am thinking that the Owyhee Butte lava must predate the Bogus Bench lava. Field relations suggest that the gravel that pervasively overlies the Owyhee Butte lava is related to damming of the Owyhee River by the Bogus Bench (Rim) lava. I have not seen any gravel below the Owyhee Butte lava (forms the Artillery Rim), but Liz and I noted in July that there are hyaloclastite units in the upper parts of this package. Note also that the Bogus Bench (Rim...Brim?) lava has no gravel on top until you get a few km downstream from Iron Point. There, you find a 5-8 m thick deposit of locally derived, but rounded gravels. (I have shown pictures of this before in a previous post, but may add them again soon for emphasis). We know from multiple locations that the Bogus Rim lava flowed down a channel of the Owyhee River and overlies rounded gravel in various places. The local gravel pile likely relates to decommissioning of the dam.

Thus, the river is at least 1.92 Ma old. Note that the 4569 vent has a date of approximately 5.64 Ma. The one-sided plateau morphology of that vent and flow complex supports the idea that it formed a lake on its south side, much like Bogus Bench. However, I have not seen (nor looked hard for) gravel. My hunch is that this may be related to a precursor drainage. Speculative.

My preliminary conclusion is that the river formed between 5.6 and 1.92 Ma, probably closer to 1.92. Any thoughts?

All figures and the table in this post taken from:

Bondre, N.R., 2006, Field and geochemical investigation of basaltic magmatism in the western United States and India. PhD. Dissertation, Miami University, Miami, OH., 252 p.

http://www.ohiolink.edu/etd/send-pdf.cgi/Bondre%20Ninad%20R.pdf?miami1164916380