Leavenworth Geology

happy sunday morning to you all hope everything's going well in your world hiking today with liz above leavenworth washington late morning it's going to be 70 degrees fahrenheit today and uh i want to point out a little bit of geology before i resume hiking with a thinking about aaron donaghy this morning thinking about uh jerome lessman this morning let's start with jerome lessman since i was with him earlier this week and talked about him on friday as well we're looking south right now that's leavenworth washington looking south coming out of the high country was the icicle creek glacier an alpine glacier can you visualize it coming right down this draw that's icicle creek itself the icicle creek canyon and flowing right out towards us is a cute little alpine glacier multiple times during the ice sheet sorry multiple times during the ice age this icicle creek glacier flowed out of the narrow canyon and filled this little basin where leavenworth washington is today what's the evidence for that this is stephen porter again university of washington back in the late 1960s i don't know if you're able to pick up with us looking right into the sun but there are some linear features in those trees those are not terraces those are moraines lateral moraines of this icicle creek alpine glacier and i think maybe i can see some of those moraines through the trees here as well but i'm less confident of that but steve porter found those marines maybe he didn't find them but he he continued work on those marines i think a geologist by the name of paige now i haven't done my homework but i think somebody back in the 30s found them as well but the reason i'm thinking about jerome lessman this morning is because jerome says okay so you've got a healthy alpine glacier coming into this area sitting on top of leavenworth when you eventually melt that ice where's the water gonna go it's gonna go down the wenatchee river valley so now you're looking east down the wenatchee river valley and you'll eventually go about 30 miles until you hit downtown wenatchee and you merge with the columbia river so new thoughts from jerome's visit is yeah you got a glacier that's fine but that's not the end of the story what are you going to do with all that melt water and are you going to drain the melt water gradually you know is it going to be like a well-behaved kind of gradual garden hose leaving the valley as the ice melts and retreats back or is it more likely that you'll have some rather substantial lakes that then suddenly release and if you have sudden release of that pent-up water are those colossal floods are there medium-sized floods new thoughts for me maybe not for you but new thoughts for me now uh liz is up ahead of me and uh we're walking on these trails that are mostly uh looks like uh mountain biking paradise but uh we're on our uh we're on two feet i was up here a year ago with my geology 351 students you might remember a couple of videos from that but i'm also thinking of aaron donaghy this morning because she's been publishing on the chumpstick formation and these sandstones and shales and conglomerates are collectively called the chum stick formation and we're talking about the eocene now and since i've had all those programs this past winter on the eocene i'm now remembering some of those concepts that we had most impressive from here is the break in slope as we get out of the high country which is the mount stewart granodiorite the mount stuart pluton 96 to 91 million years old but if you break the topography and you suddenly are down in this more modest scene you cross the leavenworth fault so the leavenworth fault comes right through here and the leavenworth fault is one of the two fault bounding base the chum stick basin has a major strike slip fault on both sides do you remember that story any at fault on one side leavenworth fault on the other and even though those two strike slip faults have been inactive for more than 40 million years uh there's still a topographic reflection or topographic change from the hard crystalline core of the stuart basilisk to the softer sedimentary rocks you're like well why would you have any hint of a topographic change if there hasn't been any geologic action in 40 million years and i think the answer is it's just easier to erode sandstone than it is hard granite and sir pentanite and so it doesn't matter if you've had strike flip fault earthquakes on the leavenworth fault recently you're still going to have erosional differences let's keep it rolling i don't want any trouble here but now i think it's safe to say that aaron donaghy is not the first geologist to study the chum stick far from it but from my point of view she's the first along with her collaboration with michael eddie and paul umhofer to have very precise dates on marker beds within the jumpstick and for the first time we realized how quickly the sediment in the chum stick formation has been accumulating the crazy easy i don't think every breathing oh baby there's a workout today oh yeah i remember this spot so i don't mean this to be a rehash but you do remember from this past winter work with geologists to find these impressive tough beds that are within the chum stick formation and new dates from the mike eddy lab to get some very precise dates on those tough beds and therefore a much more accurate way of keeping track of time in realizing that this is a much more dramatic dynamic and even explosive time the eocene why do i say explosive well in the very last session session z where i had all three of the geologists on screen with me at once do you remember that bob miller stacia gordon mike eddy mike thinks he has a case for a volcanic center up in the north cascades notably the golden horn pluton he thinks he has one of the major tough beds in the chum stick here matching basically the magma chamber of that volcanic system and if he continues along those lines that'll be very fun to make some specific geologic ties between regions that are usually not thought of as connected at least not for me like you've got a layer of volcanic ash here that's a direct result of an eruption maybe a super volcano eruption in what is now the north cascades up by washington pass on washington state route 20. so to me the leavenworth area is interesting for ice age geology not major ice age floods coming through here now nobody's saying that and nobody's saying the canadian ice sheet was here but if you look carefully in this basin you find ice bringing granites from the stewart range and carrying those granites and placing those granite boulders down here multiple advances in retreats of the icicle valley glacier this is public land i'll share the gps location for the parking lot down here at the base of the ski hill it's a pretty low-key spot i kind of get the impression it's it's a spot used mostly by locals i've never been here where it's been super crowded granted i've only been here a handful of times but okay i see a family member let's test the zoom on this whoa yeah peanut butter and jelly oh she's reading reaching for the bugles just kidding she doesn't have the midwestern diet that i do much healthier than i am these chum stick sandstones are impressive and steeply dipping multiple generations of folding i think ralph haggarud who now lives in wenatchee is continuing to think and map about folding events within the swap formation which is older but also folding within the chump stick well i'm really bouncing around aren't i this summer different time frames at some point later this summer i'm going to have to start focusing a little bit more on baja bc oh boy better turn the camera off you don't want to hear the heavy breathing here so well what do you think oh you think so well that's all virgin ground for me i've i've never continued but if you see a path great i'll just get a shot here quick and then we'll go we've already got some haze i see a couple of i hope they're just campfires but okay it's late may we are actively appreciating clear blue skies fresh air you live in the american west you know what i'm thinking how many more weeks are we going to have clear air before the fire season begins that's the reality of it it seems lately so like it's extra motivation to get out here now as much as possible because we know that we just can't count on these beautiful blue skies that we've hello that most of us have taken for granted all trails well you're not kidding around you mean it you know there's a loop i'm so lucky yeah right yeah i do remember those i don't tend to think that way but yeah as long as you just slip your mind there just a little bit you're like okay that would not be good arrow leaf balsam root lupine drumstick sandstone what more could you ask for okay down the green yeah okay hi thank you i love you and goodbye

Channel: Nick Zentner

Views: 32,393

Keywords: Nick Zentner, Leavenworth geology, Leavenworth Ski Hill, Chumstick Formation

Id: 9lxCuzIdsh4

Length: 20min 19sec (1219 seconds)

Published: Sun May 22 2022