GC vs Owyhee

Dr. Jerque,

In a rare moment of 9-5 nonbillable geology work I submit:

The four observations you list (added below in italics) as some of the differences between the Owyhee and GC intra-canyon lava dams are some of the exact same ones I note in the manuscript that is collecting dust on my desk at home.
1. Volume of lava vs. volume of water
2. Mode of entry: canyon rim cascade vs. tributary valley route
3. Severity of topography (vertical and lateral trajectory of lava incursion)
4. Proximity of volcanic vent to the canyon; abundance of pyroclastic material.
This is fabulous! I look forward to hearing more about these items and your other GC observations.
-Spud

Best Owyhee example of lava dam features

The Sand Springs Wash area on the Owyhee retains the best example of a lava dam in the field area. At this site, there are two lava flows from the Saddle Butte vent to the west. The overlying flow is separated from the underlying flow by a spectacularly well-developed lava delta with pillow-laden foresets that dip upvalley. The dam forebay is a turtle-back like feature with a 'carapace' of chilled lava. The surface of the older Saddle Butte lava upstream of the dam is covered with lacustrine mud which is capped with fluvial gravel.

Upstream of this site, the older Saddle Butte lava flow overlies Owyhee River gravel at the site of the Weeping Wall where a spring issues from the contact between the gravel and the lava. Upstream of Weeping Wall, the older Saddle Butte lava contains a sequence of lava deltas and subaerial lavas that suggest a complex interaction with the river.

Downstream, the eastern margin of the younger Saddle Butte flow is wasting away on a grand scale.

First insights from the Grand Canyon

Probably the most striking aspect of my recent trip down the Grand Canyon is the stark contrasts of the intracanyon lava flows and related response of the river there with those of the Owyhee.

• The lava stratigraphy in the GC is notably more complicated than the Owyhee.
• In GC the variability in lava textures and the facies variability of related volcaniclastic deposits is much greater. Some GC volcaniclastic deposits are downright bizarre looking to me.
• In several circumstances, there is strong evidence supporting the occurrence of catastrophic flooding in conjunction with the incursion of lava into the Grand Canyon (note photo above); whereas on the Owyhee, there is no clear evidence of this.
• In GC, there are few to no really good examples of lava deltas. The Owyhee has world class examples.
• In GC, the intracanyon flows are not associated with large-scale (post-emplacement) mass wasting processes. The Owyhee has some spectacular post-emplacement landsliding of lava flow remnants and, thus, continue to plague the river for 1000s of years.
  

Bottom line is that there is great evidence in the Grand Canyon for lava dam failure and related catastrophic flooding. There is weak to no evidence in the Grand Canyon for effective, relatively long-lived damming of the river. In contrast, there is weak to no evidence on the Owyhee River to support catastrophic flooding related to lava dams. There is great evidence on the Owyhee that substantiates effective, relatively long-lived damming of the river by lava.

Obvious questions: Why the profound differences? Why is the Owyhee so much easier to dam with lava than the Colorado?


1. Volume of lava vs. volume of water
2. Mode of entry: canyon rim cascade vs. tributary valley route
3. Severity of topography (vertical and lateral trajectory of lava incursion)
4. Proximity of volcanic vent to the canyon; abundance of pyroclastic material.

I am pretty sure it involves aspect of each of these factors. Stay tuned for more maunderings and some more details on the points above.

SHRIMP in the Owyhee?? Fire up the barbee mate!

Dear Dr. Froude et al.:

I concur with Dr. Jerque. He refers to a plethora of field evidence that adds detail to the story presented in Ninad's work. I'd like to add that you may want to check out a paper from the Idaho State crowd of Beranek, Link, and Fanning (see below). This paper came out some time back and offers a few possible numbers for ages of big picture events in the region. If I recall correctly, the most Owyhee-relevant discussion items are based on only a few data points compared to other drainages studied and could be strengthened by additional analyses. Nontheless, it is pretty darn interesting to this spud farmer trapped in the concrete jungle.

Miocene to Holocene landscape evolution of the western Snake River Plain region, Idaho: Using the SHRIMP detrital zircon provenance record to track eastward migration of the Yellowstone hotspot

Luke P. Beranek, Paul Karl Link, and C. Mark Fanning

Geological Society of America Bulletin Volume 118, Issue 9 (September 2006) pp. 1027–1050 DOI: 10.1130/B25896.1

-Spud

P.S. Dr. Jerque: I think we are on the same page about the Rytuba and Vander Meulen work. I did overstate its relevance in reference to the Now Voluminous (Once Dreaded) Rim Gravels but refer to it merely in the context that it provides evidence of a long-occurring interaction between volcanism, the fluvial system, and expansive sedimentation in the region. I wonder if it is even relevant to the latest question because "The inital influx of major fluvial systems into the volcanic field after about 14.5 Ma is reflected...."(see abstract)?

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

Grand Hiatus for Dr Jerque

Fellow Yeehows. Unfortunately I will be spending the next three weeks slogging through the Grand Canyon with various experts on its geology. Special attention will be given to lava flows, lava dams(?), and all sorts of other things. I am hiking down to Phantom Ranch on Wednesday morning with a pack full of all the stuff I forgot to send ahead. Of special note is a new 10 MP Pentax camera that is waterproof and dustproof. This way I hope to get some fearless shots from the river. Recently took it to Tahoe to try it out:

I will certainly provide a synopsis when I return.

What's up with upper-tier landslides?

After looking at landslide after landslide along the Owyhee, it is pretty clear that there are several modes of failure typical of the river corridor. Of course we have the basic earthflow type (the Hole in the Ground has great examples); the basic rotational slump type (Artillery landslide complex; Heaven's Gate landslide complex); and the basic cantilever slab type failures along the margins of the Quaternary intracanyon lava flows. Yes, there are complex combinations of all of these things as well. Recently, Liz and I were noting that there are areas where only the upper part of an exposued section is peeling away...this is particularly true in areas where there are stacks of massive lavas with occassional interbeds of lacustrine sediments or, more importantly, piles of lava-water interaction deposits. The Bullseye landslide in 'Sweetwater Canyon' (name from river guidebook) is a good example. There, the upper lava flow is peeling back across a cruddy looking bed of lava-water interaction deposits (LWID). The LWIDs overlie a relatively massive stack of lavas. It appears that the Bullseye landslide's head scarp is below the peeling section. Its ultimate failure would not have been possible without the peeling in the upper tiers of the section. This makes Bullseye a lower-tier slide candidate.


There are lots of examples of upper-tier sliding along the river. Possibly the most impressive is right across from Iron Point. In that case, the failing area is pinned on rhyolite. There are several landslides in this general reach that sole-out on rhyolite. Not sure whether they occurred when the river was at the level or if they freaking cascading over the rhyolite into the river. Probably the former since the latter sounds so cool.


There are many examples where the upper-tier sliding seems to be associated with an underlying LWID (like a lava delta) or otherwise incompetent unit (like a lens of mud). In some places, the lava deltas are obviously linked to massive landlsiding; in others, they support massive cliffs. Maybe when you peel away the top, they lead to massive landslides. Probably not that simple. Any thoughts? Anyone?

Is the Bogus Lake bogus?

Check out the extent of a lake with surface elevation of 3900'...

Shockingly Voluminous (Once Dreaded) Rim Gravel, redux

Alas, brother spud, unless we are on different conceptual planes here, the paper in question does not directly address the SV(OD)RG. Instead, it is focused on the fluvial sediments in the middle Miocene part of the section, specifically the arkosic sandstone and mudstones that we see interbedded with rhyolite just downstream from AM-PM camp:

In the context of our studies, this part of the record is only a glimpse into an ancient precursor drainage system. In fact, I think that a fair amount of the SV(OD)RG in our study area is related to lava damming events in the latest(?) Miocene and into the Pliocene (i.e. the Bogus Rim).Thus, is is possible that the SV(OD)RG represent blockage of an integrated / partially integrated Owyhee. Recall that the base of the Bogus lava sits on river gravel in various places between Iron Point and Birch Creek. I suspect it was the blockage of this system in the early Pliocene to late Miocene(?) that deposited the gravels that form a flat surface at 3900'. Subsequent and possibly sporadic incision through the gravel cover after the breach formed several discernible levels of gravel. This is directly analogous to the distribution of the much less widespread and voluminous gravels above the Quaternary blockages. It is that latter point that really pulls me in. Any counter arguments? Anyone?

In the figure below, I have pointed out some features of the gravel. I have approximated its MINIMUM extent using the snow-like pattern. Have also noted the problem with the Ice Axe as Bogus Rim (stay tuned for explanatory post on that one). This is a crude mock-up. A more formal figure will be forthcoming with lots of elevation data...(just got me a Trimble XH...arrived today!).

(click on image for full size)

Reference related to the "Shockingly Voluminous" Rim Gravel

Hi Folks:

Here is a reference from my thesis that a very nice man (who once offered me a job in mineral exploration) turned me on to:

Rytuba, James J., and Vander Meulen, Dean B., 1991, Hot-Spring Precious
Metal Systems in the Lake Owyhee Volcanic Field, Oregon-Idaho;
in Raines, G.L., et al., 1991, Geology and Ore Deposits of the Great Basin,
Symposium Proceedings, USGS and Geological Society Nevada, Reno, Nevada,
Volume II, pp. 1085-1096.

If I remember correctly, I think it is pretty relevant to the dreadfully voluminous rim gravel and provides some corroboration of some of the things Dr. Jerque and others are finding in the field. Dr. Jerque may have a copy and I can scan you a copy sometime if you can't find it.

Traverse Map, PKH, July 2008

Using some very handy applications and hardware (Garmin 60csx; GlobalMapper; ArcGIS), I created this nice little map of my recent field excursion. Note that using the bridge in Rome Valley instead of the Arock route gets you into the field much more quickly. I took a ridiculously rough road out of Arock at first and returned via the bridge near Crooked Creek.

Summer 2008 on the Owyhee, Part 1

Spent all of last week on the Owyhee. Many rim hikes and a few forays down to the wet stuff. The latter with Liz and her students. Learned alot. Found a fault in Sweetwater Canyon (that between Jordan Creek and Hike-out Camp). Determined that the once 'dreaded' rim gravels are really the 'shockingly voluminous' rim gravels. As for the latter, there appears to be a culmination of aggradation on a platform at about 3900'. Multiple levels are present below this, mainly on the Artillery Rim. Found a tephra in a rare exposed section at the 3900' level near Owyhee Butte. Learned that the Heaven's Gate landslide complex (including an upper reach and a lower reach) is quite huge, particulary when viewed from the perspective of the canyon rim...wow. Can't imagine how this complex was not the source of multiple blockages and breaches. Liz nearly single-handedly augered a 4 m hole in a perfect closed depression. We found the Mazama, and certainly drilled into the late Pleistocene...but didn't find the fat tephra bed that we found in the slide below Bogus Point. For now, please view the following slide show for substantiation of most of the claims above (view in Google Maps or Google Earth for the full informative effect):

Model this Breaching Mechanism!

Chinese Landslide Dam Failure Flood in Action

This photo pair is interesting. Amazing how close the community is to the landslide dam...it so easily could have been partly buried by the landslide...but in that case, maybe the valley could not have been dammed so easily. Moot, obviously.

Landslide Dam Failure in China

The significance of these photos to the average Yeehow is quite clear. The principal landslide dam following the recent major earthquake in China has failed. These photos show the breach and the incredibly cool draw-down tongue. For some cogent discussion about this event, check out the blog of Dr. David Petley at which I found the bottom two images and a lot of commentary: http://daveslandslideblog.blogspot.com/

Damming Ruminations by Brother Spud

Hi Folks,
Here are the figures from my thesis that relate to the last post I made on friday night. I hope they help you visualize some of what I described.

-Spud


Figure 2. Exposure of the Saddle Butte lava near Read-it-and-Weep rapid (river kilometer 34.25). Exposure shows foreset beds of hyaloclastite and lava pillows, the passage zone, and subaerial lava. The foreset beds of pillow lavas and hyaloclastite dip down to the right, indicating that the lava advanced from left to right into a body of standing water. Much of the hyaloclastite has altered to orange-colored palagonite. The passage zone marks the elevation of the water surface. Above the passage zone, subaerial lava was emplaced. Exposure is ~60 m thick.

Figure 15. Aerial photograph of river kilometers 37.5–39.5 showing presumed initial location of West Crater lava dam. The Owyhee River flows to the north in this image. The red dashed ellipse marks the location of a possible spillway in the West Crater dam and/or the initial point of breaching. The asterisk denotes the location of the sediment lens depicted in Figure 16. Ryegrass Creek defines the western edge of the Saddle Butte lava flow. The West Crater lava flow entered the Owyhee Canyon by flowing down the Bogus Creek canyon. Enough lava was supplied to the Owyhee Canyon that the dam was able to grow upstream towards Ryegrass Hot Spring.

Figure 16. Photograph of outcrop relations at river kilometer 39.25. The Saddle Butte lava appears to underlie the sediment lens in the center of the photograph. The head of the West Crater lava dam overlies the sediment lens and the Saddle Butte lava. Foreset beds of pillow lavas and hyaloclastite dip down to the right in this image. Several different passage zones (indicated by PZ) indicate the lake level rose during construction of the dam. The location of the paleovalley wall discussed in Figure 15 is indicated by a dashed ellipse. The lens of sediment interpreted to be paleo-Ryegrass Creek is visible in the center of the photograph.

Speculations and Declarations from the Spud

Oooohh Boy, Here are some ramblings for you to chew on, some of which I have been chewing on for some time (years). Dr. Jerque’s previous comments are in italics. Sorry to post a dry reply without any figures--I am having trouble pulling them into the blog--will try on Sunday. Figures 2, 15, and 16 are pretty relevant to the discussion.

The upper West Crater lava in the presumed abutment on river right does not have lava-delta deposits (wtf?). In the field, it looks like a dry flow. Why would water have not backed up in this area during the blockage? The contact of young WC on Old WC marks the perimeter of the 3400 ft lake. I suppose this part could have been dry initially as the flow continued in a generally downstream direction....

Yes, the youngest WC (above the 3400 ft contour) does not appear to have any evidence of lava-water interaction. But, the uppermost flow units immediately below 3380 ft surface do transition quickly (within a few meters) into a lava pillow delta via a passage zone (see Figure 2 in my thesis). I can think of at least two options for why the lava above the 3400 ft contour doesn’t have any pillows: 1) Lava was entering the river canyon at a much faster rate than the river discharge (and the rate of lake rise) such that the lava dam growth outpaced the rise of the reservoir; 2) the level of the reservoir stabilized at ~3370 ft (perhaps because a stable spillway developed adjacent to Pruitt’s Castle or because the dam was porous). In either case, if the full discharge of the river could seep through or sneak around the dam, the crest of the dam could grow uninhibited and not be within the reach of the water.

Option 1 is complicated by the fact that we know that the rate of dam construction and lake level rise was semi-episodic because of the presence of multiple passage zones (and accompanying subaerial lava) preserved within the dam.

Option 2 could work because portions of the dam could be porous as observed by Crow et al. (2008), a spillway could have been eroded into the ridge of Tertiary that makes Pruitt’s Castle (near the white star in figure 15 of thesis) contemporaneously with dam construction and lake filling, or some combination of both. In regards to the porosity of the dam, our friendly neighborhood p-mag expert and I discussed this during the recent trip. I had originally conceptualized that the pillow lava deltas would be rather porous but our p-mag expert pointed out that they are likely rather well-consolidated for several reasons. For example, as the deltas form, they are sort of self-packing—a variety of clast sizes are settling and snuggling together as they tumble down and more material is added from above. In addition, some large clasts (pillows) could still be somewhat plastic and deform to fit the space provided them, almost welding together. Depending on the dissolved gases in the lava, its temperature, and the ambient pressure at the locus of emplacement (and maybe some other parameters), the crust of the growing lobes and pillows of lava fractures into tiny glassy quenched bits (hyaloclastite) that serve to fill any interstices in the delta. This hyaloclastite can dominate the delta by volume, leaving the delta matrix supported, and when the hyaloclastite devitrifies, lots of clay minerals are produced further reducing the hydraulic conductivity of the dam (an turning some portions of the dam tan-orange in color—see photo). In contrast, Crow et al. (2008) identified actual cinders in the presumed abutments of some of their lava dams and they even called some dams “sieves” rather than dams. Depending on how these pyroclastics in the Grand Canyon were emplaced, they could provide the necessary porosity to accommodate the discharge and stabilize the lake height. How about that? Are there other models you can think of to explain the outcrops?

In regards to Dr. Jerque’s questions about the timing of individual incursions of lava into the river and the total lifespan of the obstruction created, I think the dams are built quickly. The vents supplying lava to the intracanyon lava flows are monogenetic and probably have a life span of months, years, or perhaps tens of years, but not hundreds of years. From my understanding of Snake River Plain volcanism and the experience of those such as our p-mag expert, these lava flows could easily erupt, flow across the uplands, and build a dam in a few months or maybe several years. During that time, individual pulses of lava (flow units, cooling units, surges, etc.) added to the obstructions created by the first lavas in a tug of war battle with the rising lakes. The multiple (and rising in elevation) passage zones at Weeping Wall and WC at tell us this. The resulting dam is so geologically instantaneous that it makes sense to me to model it mostly as a single event. The details of the passage zone elevations, relative amounts of subaerial vs subaqueous lava, and volume of hyaloclastite tell us some of the juicy details of the event but in terms of the ~2 Ma history of the river available to us to model I would consider it one event. Even in the case of the SB dam, where there are two clearly different advances into the canyon (that potentially could be separated by a lot of time) we do nto see any different in age with the p-mag. We also do not see any fluvial deposits intercalated within the dam architecture that would suggest a long time interval (1000s to 10000s of years). What do you think?

One of my thesis’ objectives was to try to add data to, and refine, lava dam emplacement and breaching models (and the associated hazards) by trying to study how the rate of lava effusion into a river interacts with the river’s discharge and channel morphology to influence the structure and stability of lava dams. This objective was often overshadowed by the larger objective of just trying to figure out what he-ack is going on out there and distinguish the lava flows from one another but I do think that there is enough data to address the matter in the paper I am putting together on the lava flows.

Cheers,

Spud

Lava-dammed lakes in Owyhee Canyon

Here is a thought-provoking image that I created in Global Mapper this evening (click on it to enlarge). It shows the extent of a dam with a crest elevation of 3400 feet, which is the approximate elevation of the Saddle Butte 2 and West Crater Lava Dams (right, I couldn't get the blue from extending downstream, but you get the point). I have sketched in some likely dam locations...the Saddle Butte Dam is obvious because both abutments still exist. The West Crater dam, however, is a little harder to guess. The right (east) abutment is pretty obvious, but the left (west) one is not. In both cases, as we know, Rome Valley was inundated. Duh (in hindsight)

Other points:

The upper West Crater lava in the presumed abutment on river right does not have lava-delta deposits (wtf?). In the field, it looks like a dry flow. Why would water have not backed up in this area during the blockage? The contact of young WC on Old WC marks the perimeter of the 3400 ft lake. I suppose this part could have been dry initially as the flow continued in a generally downstream direction....

In the case of each dam, the damming event that is most well preserved 'immediately' post-dates an intracanyon flow from the same vent. We don't have any direct evidence that these flows dammed the river...but they certainly may have, or did they? wtf?

Is it of any interest to the modeling and general conceptualization of the processes that the lava events that clearly dammed the river were damming a river that may still have been in the process of dealing with the previous lava incursion from the same vent? (thus not so long ago, relative to the damming event).

Any thoughts? Break down and post some comments or, maybe, your own diagram....

First view of Geologic Map in Google Earth

Ok. So I recently learned that ESRI actually provides a kml-making tool in the toolbox. That is handy. I haven't yet figured out how to create a clean version to distribute, but this screen shot should provide some perspective on where this can go.

Shaded Relief Revelations

I used Globalmapper (more on that later) to quickly create this shaded relief image of the study area. Are most of the lava platforms that are so evident in this image related to lava-dams? The various volcanic structural forms in this image are really very striking. If it turns out that all or most of these features reflect late Neogene lava-water interaction, this is a fairly significant landscape-forming process in this region...the distribution of these features on the landscape record the progressive incision of the Owyhee River over a very long time, no?