Kittitas Valley Geology

and then I can understand what you're talking about but this is all happening at once and with all of his strengths he did have one major weakness from my point of view he wasn't the most organized guy and so even talking one question from me would be this kind of all this information given to me at once and I just couldn't handle it so the reason I've enjoyed putting this lecture together is i sat down with all of Bentley stuff from 20 years ago and by the way it's been 20 years I'm finally ready to embrace all of this barrage of information I finally had enough time to observe things on my own to figure a few things out on my own and now sitting down with all of his stuff has been very helpful much of what i sat down with i pulled out of my filed cabinet over the weekend and much of it is unpublished Bentley was was not quite as enthusiastic about sitting down and drafting things up and publishing it he liked the actual learning and the actual doing so he had cross-sections drawn on backs of pieces of paper on back of napkins and I had the good sense to keep all that stuff so I'm gonna share much of that with you tonight so we usually have a star of the show for each of these lectures in the star tonight as is Bob Bentley dr. Bob Bentley who started here in 1970 retired in 2004 and they're still with us but living down in Baja Mexico so I wish he was still here and I could go out with him and learn to follow up with what we're talking about now let's take some ideas we've had from past lectures this fall and and make a stratigraphic column of some of the rock layers that we're going to be working with tonight starting down here at the bottom let's have some greater than 50 million-year-old terrain material we know that word terrain these are pieces of rock pieces of land that came in from elsewhere and got added to the edge of North America so way way deep deep deep deep deep down beneath this building will eventually get ourselves down to this greater than 50 million year old rock which is Mount Stewart granite serpent tonight of the English tectonic complex things that were made elsewhere and brought in great on top of that let's have significant deposits of sandstone primarily but also some shales this is roughly 40 to 50 million years ago so a little bit younger sitting on top that makes sense with the law of superposition which says that the stuff at the bottoms got to be the oldest so these are rocks that are typically exposed in the upper County go up to Rosslyn or Cola Allen we're looking at the swauk sandstone thus walk formation up at blue it passed that's all sandstone and shale the Rosslyn formation the coal bearing deposits okay so that's this rough age you've know that there's lots of plant fossils and palm fronds and things like that you've heard about in the hills that's coming from this particular deposit on top of that let's get our Columbia River basalts that we have we talked about last week you recall roughly 15 million years ago a quick reminder from last week those basalt lava flows did not come to the surface here they came to the surface much further to the east of us and flowed into Kittitas County and eventually many of them got to the Pacific Ocean on top of the basalts for the first time in our series talking about something called the Ellensburg formation now there's a tradition in geology that you name a deposit after the place where it is first studied formally and these rocks in the Ellensburg formation were first studied in Ellensburg what's in these volcanic clastic sediments in other words rocks that are volcanic in origin primarily coming from the Cascade Mountains and what do they look like visually I'll give you plenty of sly but we want to think of River cobbles volcanic mudflows ash deposits that are a significant age but again I'm gonna even write it down cask excuse me Ellensburg formation rocks source the Cascades that'll be big for us okay I've got lots of visuals so this is just to get us started on top of the Ellensburg formation which again is a bunch of loose rock that were brought in from the cascade volcanoes thank you yes so of 15 to 4 so we're on top of the basalt typically although technically the Ellensburg formation includes some of these sedimentary inter beds between the basalts but let's just ignore that that's confusing so sitting on top of the basalts the Ellensburg formation that's it gets up to 4 million years ago on top of the Ellensburg formation another name you recognize the Thorp gravels also loose rock also primarily river cobbles but the distinction is first of all younger 4 to 1 million years ago but more significant to us the thorpe gravels basalt cobbles so many of us know about the cascade geology now when we realized that the salts are typically not in the Cascades instead they're and the site lava flows rhyolite lava flows lighter colored rocks generally the thorpe gravels are primarily basalts and as a result the source of the thorpe gravels are local in other words the ridges around our valley are made out of basalt Menashe Tesh ridge think for instance and as we uplifted Menashe cache ridge we eroded some rock off the top of those ridges and where that rock go it spilled into the valley so the thorpe gravels are telling us something about the uplift history the ridges around the rim of our Valley but I'm getting ahead of myself a little bit those are the players in our story now let's take that and let's draw in typical Bob Bentley fashion which is he was a fan of cross-sections cross-sections are sketches of geology in a side view underground so most of the diagrams you'll see that I'll share with you tonight from Bentley our cross-sections so let's try a typical cross-section so I visit my wife's class occasionally sixth grade science at Morgan middle school when she's feeling particularly burnt out so I come in and try to help out and I last about 45 minutes and then I've had enough I want to get out of there she's like that's one period you do it five more times so if I'm talking to sixth graders I don't mean to insult you but if I'm talking to sixth graders here's what I would do or what I have done actually with Kittitas Valley I would say that our Valley is a giant sandbox meaning that our Valley has been filled with sediment with loose rock up to 4000 feet of loose material of sediment filling our valley and to really understand what the bedrock of Central Washington looks like the true bedrock layers not just loose sediment now but the bedrock layers themselves we can't do that in the valley we need to get up and out of the valley and go visit Menashe - reg or Table Mountain they're places that are up high around the margin of the sandbox like the 2x4 is around a homemade sandbox so if this is a cross-section that has any meaning let's go ahead and make this Minesh - Ridge so that's south off to the left and here's Table Mountain over here to the north part of the Wenatchee range and so what are these rock layers here those are the basalt lava flows that are roughly 15 million years old rock layers are always flat originally so as we've learned this fall we needed to compress or squeeze these layers to get them to warp into this simple picture so Kittitas Valley is a broad syncline which is a name we have for a fold that goes down and Menashe - ridge is a good example of an Atlanta of an anticline if we get beneath these basalt which is another five six thousand feet according to drilling we'll get into some sediments some sandstone some shales and eventually we'll get down to when I have down here at the bottom we'll get down here to this material that came in off the ocean so I'm actually lying to you here how does it feel do you feel wrong I feel wrong kind of but to get a discussion going we need to start with something and this is a nice simple model what do I mean I'm lying to you it's not this simple and by the end of tonight I'll show you some ongoing work that's been happening just this fall 2010 it's very exciting and we're realizing more and more that things aren't nearly this simple but this is a place to start we're fine with this we're fine with this uh before I lose this diagram I wasn't kidding I'm gonna cut this short we're gonna go to the slides real quick because I got a lot of them for you let me modify this picture a little bit by the way I just wanted Bentley to lie to me a little bit you know he didn't have that filter right he couldn't just give me a simple picture I could learn it then we could add a little bit more he knew so much and it was all up here that we couldn't tease out the basic stuff we just had to go through all the complications my mind just couldn't handle it that's that's talking about my deficiencies more than anything else so we'll eventually get to a concept that the surface of the valley itself is not flat and those that have land here ranches etc know this that there are different levels of the valley floor these are called stream terraces that's gonna be part of our story also part of our story ash deposits blown in off the winds from erupting cascade volcano something that I've been particularly excited about the last three days I'll explain in a second so we're actually going to be having ash fall down on to the surface of our valley and causing some very recent formations so part of tonight is bedrock geology part of tonight is loose cobbles and loose sediment that has filled the valley and part of tonight is brand new or very very recent less than a few hundred years of volcanic ash snowing down in the landscape and then again before we quit I just have to share with you that computers are pretty amazing and email is pretty amazing Monday night halftime of the Monday Night Football game I got on my computer and emailed three researchers that I knew were in the valley this fall and trenching out at badger pocket Boylston Mountain looking for faults and I haven't met these people but I got their names and their email addresses I emailed them by Tuesday at noon I have all sorts of figures that they drafted up for me put in a PowerPoint sent to me were ready to share it it's unpublished information and they're still working on it but it's so easy to get this information now as opposed to just 20 years ago when I was a grad student and I was sitting in library stacks and xeroxing papers that were 30 years old it's a very very fluid exchange of information and I thank those guys right up front I'll give them credit but I want to thank them up front they were happy to share it with me they just didn't want me to share their figures with other researchers because they're still working on interpretations and things of that sort so I'm not a gifted photographer like Tom Foster and some others but I enjoy taking photo so some of these are mine and some of them are not and if they're not they'll be credited down at the bottom let's go for it Eric advance please thank you so give a toss Valli you are here we're not talking about the Stewart's much tonight we've devoted a whole night to that we're not talking much about the rocks to the north of this Ridge we're talking about the valley itself next one please I was loaned to book by Rafe I see last week an old book out of print that had a lot of early reports from trappers and early explorers and this one really worked for me this is from mr. splen who was an early settler in the valley let me read it to you quickly this is from 1861 this valley as it looked to me that day in 1861 was the loveliest spot that I had ever seen as we gazed on that lovely sight I wondered how long it would be before the smoke would be curling from Pioneer homes for here the settlers would find a paradise he was sixteen years old at the time and had the maturity to write down something like that next one please so it is a paradise not only for us culturally but geologically it's a paradise as well so we all are we're all here for a reason many of us are here on purpose even if we weren't raised here I'm not a clerk I'm not as schneebly I'll never be really a local right I'm from Wisconsin but I've been here 20 years and I know enough to share some of the geology with you next one please so here's a little outline of our slide since I have so many I thought I outline them for you let's start with some of the bedrock that I just was talking about on the whiteboard then we'll move to actually folding the bedrock and to create ridges like Menashe - Ridge will fill the valley not necessarily after we folded the bedrock I'll explain that but that's the Ellensburg formation story then we'll talk about recent activity at the surface of the value that has manipulated the geomorphology of the surface and then finally sharing these figures that I received earlier this week that I think are very exciting I'm hoping to make them exciting for you next one please so here's a Jack Powell special again much of this is Bentley's work combined with Jack Powell who was his second-in-command Powell did a nice thing here showing us a typical cross section of the Kittitas Valley summarizing much of what I was trying to do on the whiteboard here here's the water tower on top of Craig's Hill the Thorpe and Ellensburg formations the Columbia basalts here's our Rosalind formation Tianna way formation which is actually a little bit older so I was wrong sorry flock formation Engels and Mount Stewart next one please so four out of the valley and you get up into the piano way for instance we know there's this funky green rock from the Incas tectonic complex this is serpent tonight what we discussed a while back this is exotic to North America this is old oceanic trench material that was formed offshore and slammed into the edge of North America so that's not really part of our valley story next one likewise from Mount Stewart itself 93-year million year old granite a granted diorite we had a discussion about it and how far it had potentially traveled but the source of their granite is clearly not local the grand was formed elsewhere and brought to us and here's the the serpent tonight by the way that's under my son's feet that weathers - in real deep orange color in other words if we broke this with a hammer it would be green next one please get a little younger we get into the sand stones which are potentially confusing because there's things within the valley that look like sandstone but are not more on that coming in just a second but here we are up in the Tatum with Ray Foisy who is here tonight from Yakima ray took me out a few times a couple of years ago he's a plant person plant fossil person so we were looking for leaf fossils and he was showing me some secret spots up in the hills this is swauk formation similar to the blue at sandstones and blue at shales up by blue at pass next one please so here's Ray with a couple of finds leaf fossils roughly 50 million years old from old lakes that were here long before the valley long before the basalt flows came across the region next one please our first of many Bentley homemade cross-sections this one proudly with the coffee stain in the corner I mean this is just fly by the seat of my pants drawings and Bentley many times would actually include his dates on when he drew these cross sections so it's kind of fascinating to see his development and understanding the valley as he continues to map and continues to learn more he had research money in the summers typically from oil companies him and Powell so that they had motivation to get out on foot and learn a bunch of this so here's a cross-section of the state of Washington here's the Cascades here's Kittitas Valley right in here notice we have our Columbia River basalts and our older rocks we're talking about making up not only the valley here but the the entire state next one please the end of the line for the basalts are just north of us on Table Mountain so here's a dramatic change from our Columbia River basalts to our much older rocks we've hammered this pretty carefully in our lectures so we'll move on but before we do we want to spend a little more time looking at some local landmarks that are comprising this Columbia River basalts next one please oh yeah right so here's dr. Bentley there's been of course a fundraising campaign on campus but we have now a Bentley scholarship fully funded for one year for one geology major and this is part of the campaign to raise some money Andy Warhol style here I wish you all knew Bentley's colorful colorful character no pun intended next one please and Powell who's still around working out by the airport at the DNR next one please okay so Ellensburg is perched on the margin we know much about these basalt flows but we don't know much about the sedimentary inter beds and again I want to take some local landmarks in the valley and plug them in that's one thing that I think might be fun for us tonight so let's try that now with the next one please so our first stop is on the old Vantage highway heading east towards Vantage so let's start in Ellensburg let's go by campus you totem let's head out on Vantage highway and just as we leave the valley and cross the canal we start to get into the low country here and I think you'll recognize this outcrop if you've driven that road many many times next one please so does that ring a bell we're heading towards the wind turbines I just took this on Sunday afternoon next one please so if we look a little bit cleverly at what the road cut is showing us it gives us a window into what was going on 15 million years ago in Central Washington next one please if we look a little bit more carefully we realized this is a sandstone and on top of the sandstone is a lava flow part of the Columbia River basalt flows and if we look very carefully next one please we'll see these very very interesting bulbous structures that some of you know as pillow basalts and veterans of the lecture series know what that means in case you don't know the next couple slides will help you next one please so we have found these similar bulbous type basalt flows off the coast of Hawaii where basalt lavas are flowing into the Pacific Ocean so the lava is going into the water there's a shell forming but inside there's still thousand degrees centigrade magma and so our interpretation is any time we find pillow basalts we know that the lava flow was fighting water of some sort as it was crossing Eastern Washington so back to our outcrop we have pillow basalts quite a bit of the pillow basalts here so that means that there was water present when this sandstone was being created this by the way is the famous Vantage sandstone first studied advantage Washington and in many places in the pillow zone right above the Vantage there are big pieces of petrified wood in this particular location not so much due to some reasons we don't need to get into but this is the kelie hollow lava flow that's been accurately dated right above the vented sandstone beautiful contact between these two rock units 15 million years ago next one please now some of you might know what's going on here I don't know your local to have you ever stopped do you drive to Yakima have you ever pulled out at that viewpoint as you almost crest Menashe dash Ridge now ask for the tourists rather truckers that need to stop and cool their their their trucks well we go up there all the time with geology 101 students and there's a view that's very similar to what we were just looking at here the question is are they the same layers next one please they look like they might be this is wintertime here's a basalt lava flow there are pillows here's a sandstone with another basalt lava flow below again this is from roughly 15 million years ago are they the same lava flows no according to Bentley next one please these have been accurately identified as the rows of lava flow here's that same Kelly and hollow lava flow which you remember from the last spot was on top of this answer so in other words the Vantage sandstone is down here out of sight not exposed at the top of Manoj - Ridge and this sandstone is the Creek in a bed which is a little bit younger it's also visually different there are layers of sand within the sandstone that indicate that there was flow or that this sandstone was actually formed in some sort of stream system so we have the pillows to tell us that the water was present but we're carefully looking at the cross beds within the core Creek we can actually reconstruct a real specific visual for what Central looked Washington looked like 15 million years ago next one and Bentley has done this so again I haven't looked at these in 15 years that's why it was so fun for me to pull these out so let's take our time with this this is roughly 14 and a half to 15 million years ago this is Bentley sketching this out again it's all in his head from all these observations he's been able to put this together but it's not published it anywhere by looking at the cross beds in those sands he realizes that there was flow from north to south here's a sluggish river system this is long before the Menashe - ridge formed by the way right so this is a totally different geography it's relatively flat and so here's a lava flow that's come in the Kelley hollow in fact the front of the lava flow is right here so we're right at the edge of these lava flows coming from the fissures here's an old lake that occupied central Washington and this river bringing sediment to the assure of the lake so essentially the sediment we see at the top of Menashe - tells us that there was this old Delta where sediment was going into the lake then the next lava flow coming it also has pillows showing that was fighting the water but didn't quite get to present-day Vanderbilt gap so can you see how we can get these very clear mental snapshots of what this place was like long before our valley actually started farming this is back again during the time when we're actually forming the layers themselves next one please there's another Bentley special from slightly younger so we're I guess about the same time 14 and a half here's the next flow coming in the Rose a lava flow for those that know the yakima canyon rail well when you first leave Ellensburg and get into the canyon there are some beautiful pillows in the first outcrop you have on the east side of the highway those are pillows from the rosa flow coming in and the rosa is ending basically right where the Yakima River Canyon is presently located so again this is a lava flow coming all the way from Idaho and running out of gas right here where we are living today I was gonna say something else what was it oh yeah this is the rosa flow the same Rosa flow that's famous for its beautiful columns over on the other side of the Columbia River where the climbers are doing their thing so you can reconstruct these lava flows and their margins from the details of where the pillo structures are found next one please okay so you're local and you read the classifieds and you hear that there's some shale rock for sale come on out to my place I'll buy us some shale rock I couldn't figure this out for the first three years because I knew it was dominantly basalt in the valley here technically shale is a sedimentary rock that's clay at the bottom of a lake and I was wondering why people were selling clay which is real soft material from one of these inter beds turns out they're not selling shale they're selling basalt but they're calling it shale because the shale looking material is the interior part of a basalt flow so next one please what folks are calling shale rock here in Central Washington are the interior of these basalt lava flows that have a heavily fractured section where the rock that falls out of these interior parts are real platy like old record albums like vinyl record albums and so this is typically what's called shale locally here okay next one uh yeah why do we have this map again I don't remember let's go on now let's take the bus AWS we made the rocks now right we haven't formed the beginnings of the valley yet in other words the ridges we haven't formed the sandbox we haven't brought the Ellensburg formation unit all we have so far is Nebraska a flat landscape no hints of ridges the yakima is probably swirling through the area the Yakima River itself in other words but the canyon is not there yet so we got a lot of work to do if we want to make this beautiful place that AJ's Blonde fell in love with in 1861 so let's talk about folding the bedrock briefly next one please ah cattle and Menashe cache ridge Thrall and heading up over at vanderbilt gap which is where the freeway crosses the ridge next one please so here's Bentley back in the old days trying to speculate why these ridges are present so here's our valley and Menashe - and Boylston ridge out at the by badger pocket whiskey dick so he's got an elaborate cross-section and he's speculating major faults in the basalt to create much of this is it really that complicated time will tell next one please hiking down from the book near the canyon back into the valley next one please Bentley back in 72 this is two years after he arrives and I know there's a lot of detail on here but he's starting to look at folding with in some of the Columbia River basalts and then the key question is is the folding of the basalts also involve folding of the material below the Falls the below the Columbia River basalts or is it thin scaled folding in other words is it just the basalt that are folding and not these older rocks but the point is there's conjecture as to what's going on at depth to form these folds next one please if Powell comes in Jack Powell and gives us a Morgan middle school version it's as simple as this the basalt lava flows were flat originally next one we compressed them due to the Northern California block coming northward by the way and the whole clockwise rotation started we talked about a few weeks ago where we fold up we make a ridge where we fold down we make a valley simple as that may be it can be as simple as that next one please and so the layers were originally flat like they still are on table mountain but next one next one but if we compress regionally this is the Yakima River Canyon here's beavertail Bend here's the freeway coming from thrall up over Menashe - crossing through Creek and heading to Yakima next one Powell shows us there's a syncline through badger pocket there's an anticline at menage - reg there's a syncline at C that's at Creek there's a an incline at the next one so in a very regional simple story that is the story where the valleys are located we have a down fold where the ridges are located we haven't up fold but before we quit we'll realize a few complications to that next one please so here's Jack giving us names now for each of these structures and as we've talked about earlier it's not an east-west structure these are northwest-southeast trending structures and that's significant next one it's significant because we now have GPS you remember this Global Positioning System data that tells us we have a clockwise rotation of the crust ongoing today that is deforming central Washington's bedrock ongoing today there was an earthquake couple mornings ago right was it yesterday morning actually magnitude 4 over by mossy Rock that's the latest of many many small earthquakes in response to this rotation next one please here's a great image these yellow dots are city so Seattle and Spokane and Portland here's Ellensburg and Yakima and notice the orientation of our edges here kind of east west north east east west so there's radial pattern to these ridges showing us these layers literally crumpling up as we rotate the blocks from the South next one please interesting shots from space this is Yakima this is Kittitas Valley and our ridges located here next one shot of our Valley kind of football shaped and oriented north west south east lots of green because of the beloved irrigation system next one please not as easy as that though here's an anticline and Powell is telling us hey but look carefully there's also some significant faults reverse faults so not only are we folding these ridges we're also breaking them at the same time and sliding rock laterally and that's why we're generating earthquakes small earthquakes may be large earthquakes still the jury is still out as we form these ridges but I'll tell you what people around the world that learn about the Columbia River basalts basically have the concept that our basalt lava flows are perfectly flat and they don't really understand because the rocks are kind of dark and hard to see that there are some elaborate folds and faults within what most people think are just a bunch of flooded lavas coming out and are still as flat as the day they were that they were made you know where this is right this is 2/3 the way down the canyon this is Baldy Mountain near Weimer next one please okay now the valley fill is kind of tricky because we have evidence that some of the Ellensburg formation remember what's the source of the Ellensburg formation where's know where those rocks coming from the Cascades that's right so the trick is how are we getting all these rocks into the valley if they're coming from the Cascades if we form the ridges already and then bring the valley fill in there's only one way to bring it in from Snoqualmie Pass and that was the early thought that all the owns Berg formed might formation material cascade rocks must have right down i-90 the Yakima River drainage brought all those rocks into the valley and filled the valley up but I'll share some information with you that tells us that much of the Ellensburg formation perhaps did not come upstream of the Yakima River but from other sources when the ridges were low I'll go back to that in a second Eric help me baby okay let's go to another spot that most of you must know Ellensburg is down off the picture to the left to the lower right here's Thorp here's the freeway heading up Elk heights got your bearings and let's go right here along old highway 10 the old sunset highway as it winds along the Yakima River some of you know what I'm gonna show next one uh-huh uh-huh next one so I keep here overhearing conversations like I was driving to work this morning I saw some elk I almost hit one oh yeah where were you Oh father Sam's done out there by Thorpe oh yeah I got where you are I know where you are is it sandstone now I get that there's sandstone in the upper County looks kind of like this is it sandstone let's look more carefully next one please if we look carefully we see a bunch of very very light-colored rocks almost white rocks and if we take a piece of that and it's a sunny day and we look with the hand lens at those white rocks we realize it's very fragile volcanic pumice and fragile volcanic pumice is obviously from a volcanic eruption and if this was a sandstone there'd be no way that that pumice could survive stream action or beach action or any sort of sedimentary process so this is not sandstone that picture I just showed let's get more evidence for that next one please this looks darker but it was just taken on Monday morning with some students when we were out there this is a big pink ball that you may have noticed before wait ends right down here out of the picture and these are big fragile pieces of pumice here as well also there are big rocks that are suspended within this massive material which indicates that it came in quickly these are not grains of sand that came in gradually this is some sort of deposit that came in very very quickly it's a volcanic mudflow it's a lahar next one in fact it's actually a series of lahars this was also taken Monday morning it was kind of threatening skies and the Sun came out for just a second so it looks like the end of the world here a 2012 photo but it's not so I've got the central students here taking their board out of their tree and I'm taking some photographs so we have one lahar here one event many of you remember st. Helens down the Toutle River comes this slurry of of liquid concrete essentially here's another lahar here there's the third lahar here and here's our joint paint ball you'll notice that the next time you drive by with big beautiful white pumice chunks within it now the key question is which volcano are these lahars coming from the first way to answer the question is to get an age and the only age we have from this big will hard down here is ten million years old if you've got a good memory and you're a top student from this lecture series you remember that Mount Rainier is less than a million years old and this is ten million year old lahar way too old for our present cones so then the debate begins where were the volcano standing in the Cascades that produced these spectacular lahars it's almost certain now among benleah and some other researchers including Paul Hammond who works up by White Pass that an old volcano standing where a present-day bumping Lake was the source for much of the Ellensburg formation in the Kittitas Valley I'm going to say that again that's big much of the Ellensburg formation much of the volcanic elastic deposits of our Valley we think came from bumping Lake an old volcano in bumping Lake do you know where that is it's up towards White Pass it's clearly out of our Valley and what's the problem with that there is no River Valley today connecting bumping Lake area with us so what how do we do that how do we resolve those issues the ridges including Menashe - ridge were not standing ten million years ago and there was an old river system and a conduit to allow material from bumping Lake to get deposited into our Valley here Kittitas Valley since that time the ridges grew and cut off the supply that's new information from Bentley and his group before he left for Mexico and I think we're still working on that there's similar Ellensburg formation right at the base and Menashe - Mellor gardius country they're right along the canal similar Ellensburg formation staff saying that the source was from the south not from up by Cooper Lake next one please more shots from that same outcrop we've got the lahars and below the lahars we have some some river cobbles from old Yakima River deposits next one please do we have any other places in the valley where we can look at Ellensburg formation again this volcanic plastic material coming from the Cascades Yeah right in town Craig's Hill let's go there next one please hey I recognize that this is a section of the islands born islands Berg formation that matches roughly the Ellensburg formation in other parts of the valley so let's study it next one please so you've been here you've had your elephant ears and your cotton candy and you're looking at the horses and the bunnies with your grandkids nobody's looking here what this is the Ellensburg formation a great place to study this part of our valleys history I suppose we should put a plaque up or something next one so this has been studied carefully by Bentley and his students and I want to show you a couple of key spots within the street in Rafi of Craig Hill next one please so you know this this is Indian Trail an old footpath heading up from the fairgrounds from the rodeo grounds up the back way to the water tower we're gonna go up about half way and look at what's exposed right here within the Ellensburg formation of Craig sale next one please oh so here we go we're walking up this was Friday afternoon by the way next one up okay we've got some exposure and there's an ash layer really let's check it out next one aha there's a croc for scale there's about a four inch deposit of volcanic ash that's surprisingly coarse not fine ash like Mount st. Helens but coarse and we've got a date from this of about 5 million years again we're too old with this ash to have it be an existing composite cone that's in the Cascades so the jury is still out which volcano erupted to produce this ash with snow down into Kittitas Valley and that's been one of the funnest things of this past we put in this lecture together there are many ash layers in the valley Powell says 10 off the top of his head he can think of and I've had reports from the Kachinas and some other families who say come out and take a look at our ash layer is it Ash and if it is what volcano produced it there hasn't been much attention given to these ash deposits so some of you ranchers might have something your property that I'd be very interested to listen about so here we are notice also there's a facies change so we had some silk deposits in an old floodplain this big volcanic event happens is it a coincidence that we suddenly have clay and not silt above it or was there some dramatic event in the valley to change from kind of a sluggish stream system to more of a lake system interesting roughly five million years ago now next one please so again course ash means you're relatively close to the volcano typically and as the ash gets finer you're getting farther away so the fact that that Craig's hail ash actually called the Indian Trail ash five million years old the fact that it's so coarse indicates to me that the source is closed but the jury is out as to where that volcano was standing next one so back to backing away now here's that Ashley or we just looked at silt stone below shale above there's another change into some sandstone all part of the Ellensburg formation and the freeloaders up here looking at the rodeo are up here on top next one swing around to the north face of Craig's Hill where the railroad cut is can you picture that we're now on the kind of the radio station side of the hill next one that's been studied carefully by Bentley and his students this is a student from 97 who found a series of ash layers that are much younger than this five million year old Indian Trail ash including some st. Helens ashes from I'm just reading some dates now quickly a 72 thousand year old ash thirteen thousand year old ash that's definately st. Helens all plastered here as well as a significant accumulation of windblown sediment loose blown in off the winds maybe very well let's not get into that next one please so you've all been maybe along this railroad cut this is just north of the ditch here so where the most of Craig's Hill is off to our right and we're not as looking at some of these cobbles that are the radio stations right over the lip here next one let's look carefully at that let's go look it's all part of the Ellensburg formation gives us more clues next one please so I would say this is the most dominant look of the Ellensburg formation I've been showing you volcanic deposits and ash deposits but much of the Ellensburg formation is these River cobbles that are repetitive throughout the valley and I would say remember there's 4,000 feet of this in the valley we're just looking at the very uppermost portion and much of it is is River cobble stuff next one but if you look carefully there are places where the cobbles are larger and all basaltic thorpe gravels so this is still within the Northcutt of Craig's Hill and we're seeing some local Thorp gravels sitting on top of slightly older but more far traveled Ellensburg deposits next one please Steve Moe you all know him some of you do he's here tonight Steve took me out thankfully this summer to his place at my request I wanted to see his place that I'd heard him talk about before next one please so we went out this summer to his Hillcrest farms next one please and this is a view from his from his place Hillcrest get it next one please so let's look at most property here this is the valley a detailed digital elevation model map let's zero in on his property right here next one Eric one more Eric so we're right here at the northern entrance to the Yakima River Canyon and Steve Moe's property is right here visible and we realized that it's elevated above the rest of the valley floor so we're going to go with that in a second but the other reason to visit Steve's place next one is that he also has Ellensburg formation that is ruse ly correlative with the Ellensburg formation exposed in the Craig Hill area Bentley this was next on Bentley's list I don't know if Steve knows that but Bentley was on his list was to start carefully studying blocks that are in this this is loosely called potato Hill in Bentley's vernacular there's a potato history with the mole family and there are large blocks of lahar that appeared to have been transported in by river deposit and early indications before Bentley split from Mexico early indications that there was a southeasterly flow direction at Moe's place which doesn't make sense because the valley outlet Yakima River Canyon is actually to the southwest of this location so this was a puzzle that was trying to be solved and still has not been solved because the main engine for much of this Reacher's is now in another country living the good life next one please so let's go back to that terrorists idea and go to the surface stuff how you doing it's almost 8:00 I got another 15 minutes can you hang in okay great thanks it sounds like some of you are still awake and conscious that's that's encouraging next one please I'm not a big PowerPoint guy right I don't like to do this for like fifty minutes but I got so carried away with these images and got sent these images I wanted to share them to you okay let's look at recent developments geologically recent now thousands of years ago at the surface next one please so here's a Bentley sketch showing the idea of that if you look carefully at the elevations throughout the Kittitas Valley there are flat benches at the top of the Ellensburg formation and if you look at many of these flat benches they match in elevations even though they're on opposite sides of the valley or opposite sides of the Yakima River in some cases the concept is each of these benches which we call terraces stream terraces are places where the Kittitas Valley floor once was in other words two million years ago we think the valley floor was here and there was nothing but material filling the valley to this point but recent that tivity tied to glacial activity and outwash or melt water coming off of the front of the glacier which we're going to get to in a second is responsible for these younger Valley floors until we presently cut down here next one so Steve excuse me so so here's the current valley floor looking up towards the mouth of Menashe - Canyon so we're all comfortable with that the freeway is built on that right in town next one but you go out to Moe's place and we've got a beautiful flat valley floor but it's not at our current valley floor of the Yakima River it's perched high in fact the Yakima is down here in the trees and we're a good few hundred feet above that so this is a terrorist next one another view of it look at how flat that is potato fields up here on an old valley floor that's been abandoned by the Yakima River the Yakima River has cut down to a lower elevation next one Bentley didn't publish with paper back in the early 80s here's the northern half the northeastern portion of the Kittitas Valley floor so Ellen's burgers down here each of these guys are elevations that match and our terraces above the current valley floor next one up I thought back again modern flood plain old valley floor there's six or seven of these different terrorist levels throughout the Kittitas now if you look for them it's pretty clear next one another shot of the same thing so we have our 101 students come out and try to try to postulate why the river suddenly left this valley floor and cut down to here and it's tied to periods of glacial outburst next one again up by Thorpe old valley floor steam terrorists new valley floor it's up by the party barn next one let's go right out here do we have evidence that the glacial ice was in the valley yes indirectly by this terrace story but more specifically we have evidence of glacial activity in the valley big marine a ridge of glacial rocks that tells us exactly how far how close the glacier got the Ellensburg it's right out here by where next one the thorpe fruit and antique mall even my students can recognize that landmark as they go home every weekend so out close to here another couple miles west of this landmark next one Hin thorn another old professor in the geology department a couple summers ago tipped me off that they were quarrying for whatever reason up on hill kites into glacial deposits that i should go up and check it out so I did next one this is right next to the freeway and I don't know what they were doing they filled it in by the time I got up there but check out the poorly sorted rocks that are telling us that this is all rock that was brought in by glaciation next one the surprise to me was it was mostly basaltic so these were deposited by the ice from up valley but not very far traveled because it's all basalt and once you get up towards Easton and further up you're out of the basalt so that was a shock to me next one but the point is we've got these big boulders that only could have been moved by glacial activity at least that's my interpretation next one yeah so here's the three lanes climbing up and if you get up on top of the ridge by the cell tower where I was I guess not public property but whatever I'm a man of science I can flash my card we've got we've got our poorly sorted rocks that in here here again is that moraine next one next one another Bentley map showing the Thorp prairie moraine and all these glacial deposits up here at Elk heights next one please okay we'll keep going next one we have ash coming into our Valley here is the amount of real estate that still has Mount Mazama ash from 7,000 years ago the explosion at Crater Lake here's the area that still has Mount st. Helens ash from 1980 next one please so if you go up in Rainier Park you find all sorts of ash deposits what kind of ash deposit history do we have here in the valley next one most of us know that this is the most famous place where we have ash and I've got breaking information for you as I emptied my file cabinet I found a study by one of Bentley students back in 97 and he's got good data to tell us this is Rainier this is not Mazama it's way too old brand new information to me couldn't believe I didn't know about that paper next one please so this is from Brent lenses 1995 study under the direction of our esteemed Bob Bentley there is some Mazama ash at the top of that cut that's roughly 7 these are ages and thousands of years ago so roughly 7,000 years ago he's got good compositions and ages that match Glacier Peak ash a couple of older st. Helens ashes from 13,000 and 36,000 and so that big fat actually are down by the tracks can't be Mazama from 7,000 years its way too low in the stack to work it's below these ashes that are well-defined age wise but also compositionally court indolence it matches Mount Rainier age undefined but definitely older than 36,000 put that in your pipe and smoke it next one so we're talking about ash being blown downwind from an eruptive cascade history we must have a lot of ashes we're downwind from the Cascades right next one Don ring who's not with us tonight but was the with us the last few nights also retired geology professor out there by the chair two weeks ago said you know there's a Mazama ash out by kid at ash don't you know I didn't know that Don yeah head out there I think I've got a little slide let me dig it out for you so this is not his slide but can you picture where we are we're on the freeway heading to Vantage we're not up to ryegrass yet here's the old trestle railroad trestle crossing the freeway we're not far east of get a TAS next one in fact we're right here so here's kid a TAS part Creek Road crosses the freeway got it here's Boylston here's Vantage highway okay Don ring Doug got his slide delivered it to my little doorstep I appreciate it next one so here's his photo from 1975 with a very clear Mount Mazama ash that somehow I did not know about it even though I've lived here 20 years it's kind of embarrassing I've since visited with Jack Powell about this he was out there awhile back looking for artifacts Native American artifacts didn't find anything right below but he's pretty sure it's Mazama ash as well Don thought maybe since 1975 this is not as obvious so I went out hunting Sunday afternoon next one and found it just as obvious as can be still right there people zipping by on the freeway back and forth looking at their cell phone as they're driving with their iPod in it's right there next one right there freeway next one Mazama ash 7,000 years according to ring and Powell I haven't seen a study yet maybe it hasn't been worked up chemically but that's the going thought next one finally please hang with me this is some of the best stuff I've got at the end here if you can hang with in the last three years there has been a dramatic renewed interest in Kittitas County geology not by the geology department here I'm embarrassed to say people from the University of Washington people from the USGS in San Francisco coming up here and looking for new data based on technologies that are now being used and let me tell you what two technologies can do to refuel interest in an area next one please this is lidar we haven't talked about it at all this fall but we talked about a briefly last spring lidar is a new way to get very detailed information about the surface of an area you fly over an area you have instruments at the bottom of a plane to measure distance between the recorder and the ground surface it's basically laser technology as I understand it I'm not a techy guy but the point is we have light our information from this slaw Charlie Rubin from our department managed to talk somebody into doing it and let's zero in a little closer to see the benefit of this lidar information next one Eric entrance to the Yakima River Canyon here's the freeway for goodness sake here's most property potato Hill so in a regular photo we wouldn't really see that elevation but we're looking for subtle features now that we can pick up with lidar technology old scars of the Yakima River next one so even a part of this lidar scan was in downtown Ellensburg so you can actually see Craig's Hill next one please so here's the rodeo crowds and the scarf where Craig's Hill is located where I was showing you the ashes here's campus your totem here's the radio station next one here's my house next one so what's the benefit of this well let's go to a typical map showing back down near Thrall at the front and this is a pretty impressive boundary slope changed between Menashe - in the valley floor right this is where you hike up to the book at the parking lot next one Bentley back in the day said well this major change from the ridge to the valley floors because of a big thrust fault that's at the base of the ridge so we've actually just shoved a bunch of basalt northward to create that escarpment that may still well be true but this lidar is happening is find smaller structures that Bentley could never find even though he was a skilled field mapper next one so here's the level of detail you can get from these images so we're close here is again the freeway heading towards Thrall here's the yakima itself coming right up against the ridge and these guys at University of Washington have taken this image and I've started scouring the hills for faults and ultimately are trying to make a case that we are at much greater risk seismically than we thought even a couple years ago so that's coming before we quit hang with me take another vitamin or something keep going next one please you know the rule right if I say we have ten minutes that means we got thirty minutes more okay so let me give you some examples I eighty two to Yakima sila Butte got your bearings Sela down here here's the Canyon Road do you know Burbank Creek so we go to Burbank gate come up this go to gust spring which is no place I used to teach with Bentley and let's look at what these University of Washington guys have found next one I should give you their names this is Brian Sherrod or Sherrod I guess again haven't met him but he sent me funky stuff like this but let's go on Eric turns out you can manipulate that data to have a very detailed map let's do it again Eric now we get a slope shade map they call it you know let's go to Burbank and see what Brian was able to find Brian Sherrod the University of Washington next one so he said ok I've got this new lidar data here's Burbank Creek and I'm looking for false next one he says hey I think I see something here strip the vegetation away very very detailed imagery next one he enlarges it these are Brian's slides that he sent me Tuesday morning unpublished data he not only sees this fault scarp or in other words where the ground has been broken but the valleys in between these little creek bottoms are also deformed which is the big news because that indicates this is young earthquakes that are happening much more recently than previously thought next one please he actually has now taken the light our data and measured the height of the scarp not a big deal he's got permitting for two more trenches that he's going to go back and revisit this fault in 2011 so much more is coming on this he has yet to get any ages from layers that had been broken to figure out when earthquakes have happened in the past but many of us evoke a minority who know these structures in eastern Washington have kind of mentioned hey yeah it's true the west side has these faults but if many would come and look over at our stuff with new technologies I think would realize that the earthquake history here is maybe just as rich less people over here so the money doesn't come here is easily you know that next one this isn't a political science lesson so here's Brian and the fault scarp he is interpreting is right here just north of Burbank Canyon let me give you another example closer to home next one back to Don rings Mazama ash layer-- coincidentally where I was just out on Sunday afternoon looking for the ash sherrod sends me images and says yeah we got another one right out by Boylston you know where that is matter of fact I do Brian yes I do so he has found a brand-new fault just two and a half months ago September let's look at the lidar technology from there next one so they've got lidar from Kennett aster I didn't know that I thought it was just in the canyons I got to find that information you think you see a fault here here's the freeway that's not a fault here's park Creek coming in two different and that's not a fault next one sure Saren says yeah I think we got one there next one so they took a backhoe and made a trench some of you are from out there you were reported to me that you saw them working out there and the soil was still thin they were disappointed they they didn't get very deep with the backhoe before they got into some pretty hard rock so they hand dug part of the trench and got this next one actually sorry this is back down the weenus but anyway it gives an impression of what they're trying to do they're trying to expose the fault find some layers that they can date using carbon dating and figure out how many earthquakes have happened on the fault next one so here's I guess the University of Washington student with what one of these faults look like in one of these trenches next one and there's all sorts of annotations now from Sherrod showing where the fault scarp is what the fault looks like and samples they've taken from both sides of the fault next one back to our place out by Park Creek here's the fault scarp crosses the freeway Park Creek itself there's a scarp going right underneath the freeway again the excitement is that there's deformation or faulting of the valley floor right under the freeway from indicates way younger earthquake activity than we ever thought that we ever drink even Bentley I don't think would have anticipated that even Bentley godlike Messiah Bob Bentley next one so here's a profile of the Yakima River floor as it goes to the canyon here's a profile of part Creek coming down over there by Boylston and here's this clear fault scarp a clear drop that shows where that recent groundbreaking is so this is work in progress still unclear when that last earthquake was on that fault that's probably coming in the next year next one here's Bentley's old sketch of the area showing an anticline underneath Boylston here's par Creek on this side and Ellensburg on this side so that thrust is not part of the story here next one skip it go ahead finally a series of slides before we another technology this is where we'll quit our our faults in the Kittitas Valley connected to the now well-known fault in the Seattle area do they continue beneath the young lavas of the Cascades this is a guy named Rick Blakely who also was very open with his work and it's all done in the last year and a half breaking news here next one please I'll go through this quickly the basic concept is this is arrow magnetism work so again you fly over an area and you measure magnetism of rock and geo physically you create a map showing which rocks are heavily magnetized like basalts and things like shales and sand stones which are not magnetized very well so this is only good if you can tie it with field mapping at the surface but Blakely thinks that he sees them things to tie us in the subsurface between Central Washington and western Washington very exciting next one I say that enough you'll believe it very exciting so here's Ellensburg and seattle and tacoma and we know the Seattle fault than their Tacoma fault our question is are our faults that we're finding here a continuation of these structures and what's the nervous part if we have a big earthquake on this Seattle Fault does that mean that that thought ruptures also over here because we're all part of the same structure next one so I just am showing it to this partly because it's brand-new data secondly look at all these faults that maybe didn't know about that are all shallow crustal faults that produce moderate earthquakes at least that's our current understanding next one all these yellow dots are moderately sized earthquakes including the the one that just happened yesterday morning over by mossy rock or Morton next one and again we're trying to tie in a TAS Bally faults to what's on the west side next one so here are some of the arrow magnetic work to try to make that case I don't know much about this I'm gonna go relatively quickly plus you're probably tired of this by now next one so look at this detailed imagery from Blakely again the pinks and reds are highly magnetized rocks the Blues are lowly magnetite low magnetized rocks and you're trying to look for patterns to connect these structures based on this subsurface imagery next one there also tie in the wells that we've used from natural gas and and oil exploration to make this all work with real field data as opposed to the arrow magnetic data next one and we're leading I'm afraid to this story than what we thought 20 years ago was a separate set of faults here and much much older inactive faults on this side it's looking more and more like this is much more connected than we ever thought and therefore our seismic risk goes way up and we should really think about being in a masonry old building like this last one Eric so we wrap it all together we evolve our plate tectonic knowledge we involve our clockwise rotation we evolve our volcanism in Oregon and our earthquake activity in Washington and we realized that we continue to learn about the geology of the region yes a lots been done already but there's a lot of new stuff coming out and I hope to keep on top of this and can't elite continue to deliver this breaking information to you the best I can thank you for coming out tonight you

Channel: Central Washington University

Views: 56,511

Rating: 4.8516555 out of 5

Keywords: Central Washington University Organization, Geology Field Of Study, Washington (US County), Ellensburg Citytownvillage, Central Washington University, Ice Age Floods, Cwu, Cwu Geology, Central Washingtion University, Earthquake, Cwu Geological Sciences, Geology, History, Flood, Education, Zentner Geology Lectures Downtown Ellensburg

Id: v6LtXsViDNI

Length: 71min 25sec (4285 seconds)

Published: Mon May 06 2013