I missed the live stream on this episode but am watching the replay. I really liked having the speaker, Mark Sweeney, first. It made your discussion and questions more relevant.
Watching again, and I want to reiterate how exciting Mark's information is! Sure gives us another long look into geological time, and expanse! Your questions Nick were perfect. I just loved this session. Thank you so much.
Nick, the second half of the episode was like watching a murder mystery unfold. You teased us right at the end, and left us dangling,😢 about whether a volcanic source for the big melt has or can be found. Can't wait until Sunday to find out!
What a great show! Love the combination of scientific competence with the humility to describe what we aren't sure about. Learned so much about the Palouse
Hi. My main take away is the immense volume of loess. Where did it come from? Mark Sweeney at 1 point indicated floods followed by sedimentation, drying and wind. Could that process have started 1Ma? What if all of Washington was a basin behind Wallula Gap? Much like Nevada is now, the Gap did not exist. Outwash would have ponded and sedimented, then dried and blown away. For many of the glacial sequences. Then at one point the ice was at the Spokane CRB and overtopping them and the ice dam on the Clark Fork broke and Lake Missoula drained over/into the Spokane ice and began cutting through Wallula to form the Gap. Since the gap was small it took years at first with more sedimentation and drying and blowing. Eventually the precoulee valley's were cut and when the last HUGE floods came down the final scouring was done. Or something like that......
Mark, thanks for being a guest. I would really like to learn more from you in the future. I'm really old. As a teenager, my mother from Illinois would talk about loess (sp?). I, of course, tuned her out. Now, I am trying to learn about it,lol. You, Skye Cooley, and Jerome L. (Sp again) are my current sources of learning. I found your material today helpful for my understanding. Thank you for taking time from your very busy schedule to talk to us today.
Im a Colfax native from the Heart of the Palouse Country, and I've been waiting impatiently for this episode for obvious reasons. Growing up there as a kid, I had no inkling of just how unique and rare the rolling grain field hills are from a world geographical and geological point of view. After Nick's lead in from the previous episodes on Bretz and the theories about the Spokane ice sheet and its possible source for large scale flooding, I'm all ears! For Mark, regarding the relatively worldwide rarity of the Palouse loess and the unique Southeastern Washington topgraphy....as an adult and fighter pilot, I deployed several times to NATO exercises in Central Anatolian Turkey near the city of Eskisehir. I observed the surrounding terrain to be visually very similar to the Palouse, and also rich cereal grain farming country. Coincidence, or possibly geologically linked?
Wow, lets go for Spokane (sub)glaciation, tunnel valleys underneath the icesheet! Why not, just so exciting!! You actually clearly scored for Bretz even!! I'm buzzed, by Nick😆💗!! Thank you, Mark SO much for being comfortable talking about your research, letting regular people like me understand, and paint pictures about loess and glaciations!! Awesome Episode Q, I'm so glad I tuned in live for this one!!😘💞💗
I’ve been waiting for this episode. Fantastic stuff. And you answered my question about Loess being Lake bottom sediment in Lake Missoula. Fantastic to know that actually happened. I’ve mentioned in other videos, I live in the Yukon in Canada, where an ice sheet used to be, which retreated, leaving a large glacial lake, the lake was held back by a huge terminal moraine which eventually burst. Remaining here now is the Lake bottom sediment Loess, called locally here as Clay Cliffs, but they are actually mostly silt. But these cliffs are over 200 feet thick. I wonder if there are similar cliffs anywhere in what used to be Lake Missoula. I’ve looked without much success
Nick, you are blowing my mind again! Now, I want to learn more about glaciation without forming moraines. Recently there was one of these floods occur in Iceland. I paid more attention to it because I had heard Jerome use this J word from Iceland and that it is a volcanic glacial flood. I don't think you know that volcanos are a lifelong fascination for me. In the last 3 years, learning about them is now an obsession for me. I'm, of course, learning all I can from you. I have been your fan since finding you on PBS many years ago. Anne5440 from E Wenatchee and 1971 CWU alumni. Thanks for this video. I'm getting up early for tomorrow.
Loess is rich in minerals and loose, which allows good drainage and roots to grow deep into the soil to find moisture. That leaves beind organic material after each harvest.
Its not unique to this area you also get similar loess deposits downwind of other continental ice sheets the example that is most politically relevant is Ukraine where loess makes or rather made, the soil some of the richest in Eurasia.
There's a map showing the loess deposits in the Lower 48 and Alaska. It shows none from the Oklahoma Panhandle across Arkansas until close to the Mississippi River where there's Crowley's Ridge. The ridge starts in SE Missouri and extends down into NW Louisiana. It's a strip of uplifted land created by the New Marid Rift Zone where the Ohio River ran to the east and the Missouri -Mississippi River ran to the west. The uplifted land captured the loess blow in from both directions. It also blew in seeds from the Appalachian Mountain chain so was covered with hardwoods and plants such as ferns, gensing, orchids that grew in Eastern Tennessee and Western Carolinas. It was named after a settler who was awarded land in NE Arkansas for his service during the War of 1812. He found the land to be a swamp due to subsiding during the New Madrid Earthquakes so filed for another parcel as compensation. He selected some land along a ridge that was habited by natives that had established trails running across it. Nobody lived below on either side since it was mostly swamps swarming with mosquitoes that carried malaria.
Multiple stages of glaciation would bring multiple periods of loess production, as well as changes of wind patterns as the climate swings back and forth.
Beautiful intro Nick! Could you one day do a focus on Mount Whitney and the Kern River? We are the most south east part of this section you do such great work on and we get allot of Earth Quakes and I’m always wondering if the Sequoia national forest is the newest or oldest mountain range? It seams like the spiral motion of the crust up by you is like the eye of the hurricane and down here we are like the outer edge of this pressure build up by you! Thank you brother!
Great presentation Mark and Nick! Thanks for taking my question about where the westernmost loess came from. (Maybe an answer will pop up here in these comments!?!?) I enjoyed learning that loess comes from the silt and sage interaction, sort of a wind-fed half-living solar organism! As to the lack of loess just south of Spokane, the glacier didn't necessarily have to "bulldoze" it away, I reckon just the glacial ice being there would prevent the accumulation of loess in the first place.
This is adding up nicely to me. The elevation down on the snake River at this point 46°33'33"N 118°15'11"W · 909 ft then up at Spokane at this point 47°39'25"N 117°26'56"W · 1,817 ft. … 908ft of drop to get to the snake river. Maybe glacial lake Missoula was covered in ice at one point also scouring out lake Pend Oreille with subglacial melt. Each glaciation advance and retreat pushing the till around. With occasional surges enhancing the erosion.
You can never cross the ocean unless you have the courage to lose sight of the shore.” 🔳Christopher Columbus. I am having a blast with the series…lends itself to my contrarian nature. THANKS NICK…
OMG Mark. I read your paper, but your presentation today made me so much more intellegent. Dunes vs Loess. Pasco basin = one big layer of slime after floods which dries and gets blown east. Going back to SR26 to look at the Washtucna exposure. From Battery Fully Charged 😊
I hate to take a dip in the glacially fed White River off of Mt. Rainier. It makes me gritty. But now after Mark’s description, I can imagine a million years of glacial rivers flowing out of Montana, Okanagan and Columbia drainages leaving icky silt which gets picked up by out burst floods and leaving a scum around Pasco, which later dries and gets blown back to the Palouse again and again. FANTASTIC!!! From Battery Fully Charged.
If ice advanced to the large river valley, crossed it, and started advancing up-slope on the south side, wouldn't it be logical that any morainal material from north of the river would have been dumped in the river channel, then the ice would have overrode it and some of the river flow, and the only till deposits on the south side, beyond the river bank, would be stuff picked up on the way UP the southern channel to the plains (or embedded higher in the ice), and would have been fairly negligible, and easily washed away in the alluvial outflow down the scablands - especially by later Missoula flooding. Picture trying to sweep dust across an empty groove in a floor - you will lose most of the material into the groove.
Great mental images of the glacial environment generated by this discussion and Nick in a winter coat seems appropriate. Maybe next time a hooded polar bear parka (or mastadon).
I can't wait to be live with you on Sunday... So if we are going to talk about the ice sheets, why is there not discussions about how they formed? As I plan my "Glacier lab," I debated taking layers of last week's snow and stacking them, versus buying a bag of ice cubes or a solid block of ice. In all the discussions, its like everyone assumes all the glaciers are just one giant ice block that moves forward and back... but visiting Mt. St. Helens, Mt. Bachelro, or Mt Baker, the snowfall creates layers and layers. Why could the ice that covered teh lower reaches in the Spokane area been just an accumulation of snow... like the layers in the Mountains of interior Antarctica, or the canyons of valleys of Mountaints in the Rockies/ Alaska? I don't see any reason why teh ice over spokane wouldnt have melted and the water/ice broke up and flowed down the Spokane/ Columbia river as well, right out of Newport/ Astoria/ Grey's Harbor.
Thank You. What was the "Depth", The Thickness, and Weight of the Glacial Ice Sheet when it had been at its Peak, before any drainage upon the Columbia Plateau? Before any potential volcanism under the ice-sheet?
I am with you Nick! The glaciers had to encroach upon the scablands northern margin. The ONLY way you get the Coulees in eastern Washington is cold pressurized high volume release water from UNDERNEATH the glacial advance. Water running over top the water is erosive but nothing like pressurized water. The coulee walls and the material accumulating along the walls will tell you the age of the coulees. How fast does the material form on the edge of the coulee walls? Bretz was correct on this question about the age of the Tallis (sorry if I am using the wrong term). Wenatchee, Moses and Grand Coulees all have different ages. Solve this and you start to understand Bretz’s understanding of coulee forming Major (Stages 16-4) vs wimpy (Stage 2). Love this episode. Sucks I couldn’t get to it sooner.
Excellent program once again. I wonder though about the Spokane Flood. Wouldn't there need to be some evidence of lake shores and or lake beds in the area or just north of Spokane in the mountains/valleys of southern B.C? Checking Google Earth, I see what appear to be lake shore lines just off Hwy 173 north of Downing where the hwy turns north. Ths is in addition to the flat wide open river valley a possible lakebed rather than only a river valley?
Another very interesting episode. If the ice didn't reach Spokane, how were those channels cut? How is that water getting that far east on the basalt plain? Also, I would really like to be able to see the live chat in the replay. I am missing all the side conversations and answers from the other geologists in the chat. Thank you for the effort you are putting in these classes.
I find interesting your idea that the ice-sheet could have pushed loess and soil forward and then leaving bare the basalt. The fact that it is a strong plateau relatively flat is a peculiar situation to begin with, isn't it ?
Would the thousands of years of possible spring floods from the Cascades have produced enough silt deposits to provide the source of at least part of the loess found in eastern Washington?
Do most geologists now believe that there were large ice-age floods in Washington prior to MIS 2? If not, then to what do they attribute the much older layers of loess in eastern Washington? Perhaps there are different interpretations of how that older loess got there. Might be interesting to hear the debates between these different interpretations.
So if Lake Missoula has nothing in the older cycles, could the lake(s) have been somewhere else like the Okanogan or further up the Columbia? Since there are no older moraines in western Washington, could the older glaciations have been smaller in the older glaciations, and in the bigger last cycle the ice erodet most of it away?
At 2:08 you read Brett’s version of older/bigger - younger/smaller. However, Brett’s wording in the latter referred to “the escaping waters.” I take that to mean the under-ice waters only, which makes sense because of its more northern advance. But GLM water could be in addition to the “escaping” waters. Thoughts..??
Watching in reply, Nick respectfully can you ask a ice expert to weigh in because I Agree that the water cam from under the glaciers. Modern technology I believe will support our water source. thanks again for the journey
Hi Nick, With the latest and most persistent floods washing through the existing channels and depositing RED material, it seems most likely that the oldest ( blue) material was the hardest hit. Outwash material contained the most sediment, unlike the Masoela (sp) water which would have been clear as much of its sediments could have settled behind the gap.
In principal there is evidence for the Cordilleran ice sheet having formed in the Pliocene around the high mountains of Alaska and BC so even glacial loess could be old indeed. Interesting to see several generations of loess removal and re-deposition. Loess may have gotten into the basin through earlier flooding perhaps as far back as during the Pliocene since there is some work which suggests the Cordilleran ice sheet was more extensive early on before most other ice sheets were able to start forming in the Northern Hemisphere. That said at this moment while it can't be ruled out I would be cautious linking the presence of loess to an ice margin was in the area of eastern Washington around Spokane since as Mark Sweeney said loess got down to Louisiana. Its an interesting idea that perhaps there wasn't moraines but yeah its those paleochannels may be another story. Perhaps we are dealing with deep subglacial channels? Also I think the potential evidence of Pliocene presence of the Cordilleran ice sheet with the decline of the ice sheet in later even Oxygen Isotope Stages. Well those are my thoughts in replay
it is a legitimate thought process considering most of dating and conclusions are also thought processes with no witnesses to the contrary ... however, I think my question has been answered at 1:20:00 (or thereabouts) ... it comes down to the current view of the delivery system, and perhaps it is time to do exactly what Nick is working on - - why was the ice sheet around Spokane dropped in the 1960s. It is a good question .... fascinating to hear and see this study, as well.
13:26 "A study in progress?" Geologist Ned Zinger walks the site of the Milwaukee Road Pacific Extension. The juxtaposition of unimaginable geological time, and a railroad that closed in 1981... punctuated by the thoughtful lone figure of Ned; himself eclipsed by the standing stone, a representation of Gaia and the long years of her existence. Invites us to consider our own place in the continuum, and changes that occur both within and without our lives. ...that'll be $35 million please to any elite who wishes to use art as a vessel to launder money and/or avoid tax.
@NickZentner ( My Vision ) Great to be able to catch-up '!'. My ; Bretz hit a 'screwball' : re- 1924 when he reached < LOC: perry >. He ( Bretz ) , gets 'pinched out' between ; Columbia River , MiS 4+ : Missoula Flood , MIS (Stage 2-4) : Lake Bonneville, MIS 4+. 'TILL ( no pun intended ) next time ... tbc .. ps- battling it out in the corners. pps - ? How far Did the Columbia get re-directed , after getting pushed : CRB's. *A couple of interesting LOC to investigate (1:47:19) Columbia River to the . ? Where are those Leoss hills ? , ?! Swept away from the ~Over-flow~ of the Columbia River ( MIS 4+ ? )
"I'm just a teacher." Such an understatement!
Best teacher I’ve ever seen!
I missed the live stream on this episode but am watching the replay. I really liked having the speaker, Mark Sweeney, first. It made your discussion and questions more relevant.
The Palouse makes so much more sense now. Thanks!
Watching again, and I want to reiterate how exciting Mark's information is! Sure gives us another long look into geological time, and expanse! Your questions Nick were perfect. I just loved this session. Thank you so much.
Great episode Nick, thanks! : )
Nick, the second half of the episode was like watching a murder mystery unfold. You teased us right at the end, and left us dangling,😢 about whether a volcanic source for the big melt has or can be found. Can't wait until Sunday to find out!
more puzzle pieces and mind blown! great discussion.
Hello from Connecticut!
What a great show! Love the combination of scientific competence with the humility to describe what we aren't sure about. Learned so much about the Palouse
Hi. My main take away is the immense volume of loess. Where did it come from? Mark Sweeney at 1 point indicated floods followed by sedimentation, drying and wind. Could that process have started 1Ma?
What if all of Washington was a basin behind Wallula Gap? Much like Nevada is now, the Gap did not exist. Outwash would have ponded and sedimented, then dried and blown away. For many of the glacial sequences.
Then at one point the ice was at the Spokane CRB and overtopping them and the ice dam on the Clark Fork broke and Lake Missoula drained over/into the Spokane ice and began cutting through Wallula to form the Gap. Since the gap was small it took years at first with more sedimentation and drying and blowing.
Eventually the precoulee valley's were cut and when the last HUGE floods came down the final scouring was done. Or something like that......
Mark, thanks for being a guest. I would really like to learn more from you in the future. I'm really old. As a teenager, my mother from Illinois would talk about loess (sp?). I, of course, tuned her out. Now, I am trying to learn about it,lol. You, Skye Cooley, and Jerome L. (Sp again) are my current sources of learning. I found your material today helpful for my understanding. Thank you for taking time from your very busy schedule to talk to us today.
Im a Colfax native from the Heart of the Palouse Country, and I've been waiting impatiently for this episode for obvious reasons. Growing up there as a kid, I had no inkling of just how unique and rare the rolling grain field hills are from a world geographical and geological point of view. After Nick's lead in from the previous episodes on Bretz and the theories about the Spokane ice sheet and its possible source for large scale flooding, I'm all ears!
For Mark, regarding the relatively worldwide rarity of the Palouse loess and the unique Southeastern Washington topgraphy....as an adult and fighter pilot, I deployed several times to NATO exercises in Central Anatolian Turkey near the city of Eskisehir. I observed the surrounding terrain to be visually very similar to the Palouse, and also rich cereal grain farming country. Coincidence, or possibly geologically linked?
Heeeyyy. I lived in colfax in the late 90s.
Dr Sweeney was a great guest! So much information and well explained. Thanks for hosting him and asking great questions.
Wow, lets go for Spokane (sub)glaciation, tunnel valleys underneath the icesheet! Why not, just so exciting!! You actually clearly scored for Bretz even!! I'm buzzed, by Nick😆💗!! Thank you, Mark SO much for being comfortable talking about your research, letting regular people like me understand, and paint pictures about loess and glaciations!! Awesome Episode Q, I'm so glad I tuned in live for this one!!😘💞💗
Mark Sweeney... that was wonderful, well done gentlemen.
I’ve been waiting for this episode. Fantastic stuff. And you answered my question about Loess being Lake bottom sediment in Lake Missoula. Fantastic to know that actually happened. I’ve mentioned in other videos, I live in the Yukon in Canada, where an ice sheet used to be, which retreated, leaving a large glacial lake, the lake was held back by a huge terminal moraine which eventually burst. Remaining here now is the Lake bottom sediment Loess, called locally here as Clay Cliffs, but they are actually mostly silt. But these cliffs are over 200 feet thick. I wonder if there are similar cliffs anywhere in what used to be Lake Missoula. I’ve looked without much success
Nick, you are blowing my mind again! Now, I want to learn more about glaciation without forming moraines. Recently there was one of these floods occur in Iceland. I paid more attention to it because I had heard Jerome use this J word from Iceland and that it is a volcanic glacial flood. I don't think you know that volcanos are a lifelong fascination for me. In the last 3 years, learning about them is now an obsession for me. I'm, of course, learning all I can from you. I have been your fan since finding you on PBS many years ago. Anne5440 from E Wenatchee and 1971 CWU alumni. Thanks for this video. I'm getting up early for tomorrow.
I have not heard any mention of just how agriculturally unique this loes is. It is amazing area for growing grain crops!
In southwest Wisconsin (driftless area)the loess is many feet deep and the most fertile in the state.
One benefit is the deep silt makes it possible to farm without irrigation for wheat and hay.
Loess is rich in minerals and loose, which allows good drainage and roots to grow deep into the soil to find moisture. That leaves beind organic material after each harvest.
Its not unique to this area you also get similar loess deposits downwind of other continental ice sheets the example that is most politically relevant is Ukraine where loess makes or rather made, the soil some of the richest in Eurasia.
Awesome stuff, terrific guest, I learn something new with every episode, thank you Nick!
There's a map showing the loess deposits in the Lower 48 and Alaska. It shows none from the Oklahoma Panhandle across Arkansas until close to the Mississippi River where there's Crowley's Ridge. The ridge starts in SE Missouri and extends down into NW Louisiana. It's a strip of uplifted land created by the New Marid Rift Zone where the Ohio River ran to the east and the Missouri -Mississippi River ran to the west. The uplifted land captured the loess blow in from both directions. It also blew in seeds from the Appalachian Mountain chain so was covered with hardwoods and plants such as ferns, gensing, orchids that grew in Eastern Tennessee and Western Carolinas. It was named after a settler who was awarded land in NE Arkansas for his service during the War of 1812. He found the land to be a swamp due to subsiding during the New Madrid Earthquakes so filed for another parcel as compensation. He selected some land along a ridge that was habited by natives that had established trails running across it. Nobody lived below on either side since it was mostly swamps swarming with mosquitoes that carried malaria.
Mark mentioned basalt sand dunes is his next paper presentation at GSA in May? Are there basalt dunes in Washington with the remains of coulees?
This was awesome and helps fill the gaps.
Mark has an amazing understanding of the unique conditions in this area!
Multiple stages of glaciation would bring multiple periods of loess production, as well as changes of wind patterns as the climate swings back and forth.
Great explanation of how, what and where of Loess. And how the eroded forms have developed. Thanks!
Your productions improve at every iteration; well done Nick👍🏽
Excellent!!!
Beautiful intro Nick! Could you one day do a focus on Mount Whitney and the Kern River? We are the most south east part of this section you do such great work on and we get allot of Earth Quakes and I’m always wondering if the Sequoia national forest is the newest or oldest mountain range? It seams like the spiral motion of the crust up by you is like the eye of the hurricane and down here we are like the outer edge of this pressure build up by you! Thank you brother!
Great presentation Mark and Nick! Thanks for taking my question about where the westernmost loess came from. (Maybe an answer will pop up here in these comments!?!?) I enjoyed learning that loess comes from the silt and sage interaction, sort of a wind-fed half-living solar organism! As to the lack of loess just south of Spokane, the glacier didn't necessarily have to "bulldoze" it away, I reckon just the glacial ice being there would prevent the accumulation of loess in the first place.
Got to like a forum where you can explore ideas.
10" of snow in Boise today!
This is adding up nicely to me. The elevation down on the snake River at this point 46°33'33"N 118°15'11"W · 909 ft then up at Spokane at this point 47°39'25"N 117°26'56"W · 1,817 ft. … 908ft of drop to get to the snake river. Maybe glacial lake Missoula was covered in ice at one point also scouring out lake Pend Oreille with subglacial melt. Each glaciation advance and retreat pushing the till around. With occasional surges enhancing the erosion.
You can never cross the ocean unless you have the courage to lose sight of the shore.” 🔳Christopher Columbus. I am having a blast with the series…lends itself to my contrarian nature. THANKS NICK…
OMG Mark. I read your paper, but your presentation today made me so much more intellegent. Dunes vs Loess. Pasco basin = one big layer of slime after floods which dries and gets blown east. Going back to SR26 to look at the Washtucna exposure. From Battery Fully Charged 😊
Fermen Layton Pickett was a botany professor at WSU. They have his papers!
I hate to take a dip in the glacially fed White River off of Mt. Rainier. It makes me gritty. But now after Mark’s description, I can imagine a million years of glacial rivers flowing out of Montana, Okanagan and Columbia drainages leaving icky silt which gets picked up by out burst floods and leaving a scum around Pasco, which later dries and gets blown back to the Palouse again and again. FANTASTIC!!! From Battery Fully Charged.
I wonder if there are north to south scouring on the basalt north of Spokane, suggesting glaciers?
There is an area of Iowa covered in loess. US30 runs through it. Interesting.
If ice advanced to the large river valley, crossed it, and started advancing up-slope on the south side, wouldn't it be logical that any morainal material from north of the river would have been dumped in the river channel, then the ice would have overrode it and some of the river flow, and the only till deposits on the south side, beyond the river bank, would be stuff picked up on the way UP the southern channel to the plains (or embedded higher in the ice), and would have been fairly negligible, and easily washed away in the alluvial outflow down the scablands - especially by later Missoula flooding.
Picture trying to sweep dust across an empty groove in a floor - you will lose most of the material into the groove.
Are we sure it wasn't cold enough no river(Snake/Palouse) was flowing?
“Yes, it’s wrong!” Hills NOT dunes! Great guest. Thanks Mark! Makes me wonder still…”how does Nick know so many cool people?”🤣. Thanks Nick.
Great mental images of the glacial environment generated by this discussion and Nick in a winter coat seems appropriate. Maybe next time a hooded polar bear parka (or mastadon).
Looks just like that show coming down, and I'm in Manhattan
I can't wait to be live with you on Sunday... So if we are going to talk about the ice sheets, why is there not discussions about how they formed? As I plan my "Glacier lab," I debated taking layers of last week's snow and stacking them, versus buying a bag of ice cubes or a solid block of ice. In all the discussions, its like everyone assumes all the glaciers are just one giant ice block that moves forward and back... but visiting Mt. St. Helens, Mt. Bachelro, or Mt Baker, the snowfall creates layers and layers. Why could the ice that covered teh lower reaches in the Spokane area been just an accumulation of snow... like the layers in the Mountains of interior Antarctica, or the canyons of valleys of Mountaints in the Rockies/ Alaska? I don't see any reason why teh ice over spokane wouldnt have melted and the water/ice broke up and flowed down the Spokane/ Columbia river as well, right out of Newport/ Astoria/ Grey's Harbor.
Thank You. What was the "Depth", The Thickness, and Weight of the Glacial Ice Sheet when it had been at its Peak, before any drainage upon the Columbia Plateau? Before any potential volcanism under the ice-sheet?
RE Bretz finding the Spokane ice front: he noticed what was MISSING: loess
I am with you Nick! The glaciers had to encroach upon the scablands northern margin. The ONLY way you get the Coulees in eastern Washington is cold pressurized high volume release water from UNDERNEATH the glacial advance. Water running over top the water is erosive but nothing like pressurized water. The coulee walls and the material accumulating along the walls will tell you the age of the coulees. How fast does the material form on the edge of the coulee walls? Bretz was correct on this question about the age of the Tallis (sorry if I am using the wrong term). Wenatchee, Moses and Grand Coulees all have different ages. Solve this and you start to understand Bretz’s understanding of coulee forming Major (Stages 16-4) vs wimpy (Stage 2).
Love this episode. Sucks I couldn’t get to it sooner.
Excellent program once again. I wonder though about the Spokane Flood. Wouldn't there need to be some evidence of lake shores and or lake beds in the area or just north of Spokane in the mountains/valleys of southern B.C? Checking Google Earth, I see what appear to be lake shore lines just off Hwy 173 north of Downing where the hwy turns north. Ths is in addition to the flat wide open river valley a possible lakebed rather than only a river valley?
Another very interesting episode. If the ice didn't reach Spokane, how were those channels cut? How is that water getting that far east on the basalt plain? Also, I would really like to be able to see the live chat in the replay. I am missing all the side conversations and answers from the other geologists in the chat. Thank you for the effort you are putting in these classes.
You can access the chat afterwards. Go to comments and swipe to see chat. I did this before but I can’t make it work, sorry.
I find interesting your idea that the ice-sheet could have pushed loess and soil forward and then leaving bare the basalt. The fact that it is a strong plateau relatively flat is a peculiar situation to begin with, isn't it ?
Would the thousands of years of possible spring floods from the Cascades have produced enough silt deposits to provide the source of at least part of the loess found in eastern Washington?
Do most geologists now believe that there were large ice-age floods in Washington prior to MIS 2? If not, then to what do they attribute the much older layers of loess in eastern Washington? Perhaps there are different interpretations of how that older loess got there. Might be interesting to hear the debates between these different interpretations.
So if Lake Missoula has nothing in the older cycles, could the lake(s) have been somewhere else like the Okanogan or further up the Columbia? Since there are no older moraines in western Washington, could the older glaciations have been smaller in the older glaciations, and in the bigger last cycle the ice erodet most of it away?
At 2:08 you read Brett’s version of older/bigger - younger/smaller. However, Brett’s wording in the latter referred to “the escaping waters.” I take that to mean the under-ice waters only, which makes sense because of its more northern advance. But GLM water could be in addition to the “escaping” waters. Thoughts..??
Watching in reply, Nick respectfully can you ask a ice expert to weigh in because I Agree that the water cam from under the glaciers. Modern technology I believe will support our water source. thanks again for the journey
Having a different mechanism for the earlier events should NOT be "Radical". I would call it reasonable considering the evidence.
Reversely magnetized polouse! Let’s talk about it!
Great interview Mark! Clear n concise
When do we open the Tanqueray?
It doesn't seem a coincidence that their is a glacial lobe at the head of each scabland tract
I would be the Canadian sub glacial water is a big part of it. American exceptionalism may be biasing us :) Great talk!
Tell me more about Canada. There is obviously some dead / ghost volcanos there. Squamish is a good example. I have been there. Lots of granite there,
Hello from glacial till Peoria
What role do native grasses and forbes play in aiding accumulation of loess if any?
Nice bolo!
Do we have LIDAR for the Spokane paleo channels?
Hi Nick,
With the latest and most persistent floods washing through the existing channels and depositing RED material, it seems most likely that the oldest ( blue) material was the hardest hit. Outwash material contained the most sediment, unlike the Masoela (sp) water which would have been clear as much of its sediments could have settled behind the gap.
In principal there is evidence for the Cordilleran ice sheet having formed in the Pliocene around the high mountains of Alaska and BC so even glacial loess could be old indeed. Interesting to see several generations of loess removal and re-deposition.
Loess may have gotten into the basin through earlier flooding perhaps as far back as during the Pliocene since there is some work which suggests the Cordilleran ice sheet was more extensive early on before most other ice sheets were able to start forming in the Northern Hemisphere. That said at this moment while it can't be ruled out I would be cautious linking the presence of loess to an ice margin was in the area of eastern Washington around Spokane since as Mark Sweeney said loess got down to Louisiana. Its an interesting idea that perhaps there wasn't moraines but yeah its those paleochannels may be another story. Perhaps we are dealing with deep subglacial channels? Also I think the potential evidence of Pliocene presence of the Cordilleran ice sheet with the decline of the ice sheet in later even Oxygen Isotope Stages.
Well those are my thoughts in replay
Working in a cold office is not conducive to your health! I hope you are taking care of yourself tonight!
The plot thickens...
subglacial water flow ... is there a definitive of that possibility?
it is a legitimate thought process considering most of dating and conclusions are also thought processes with no witnesses to the contrary ... however, I think my question has been answered at 1:20:00 (or thereabouts) ... it comes down to the current view of the delivery system, and perhaps it is time to do exactly what Nick is working on - - why was the ice sheet around Spokane dropped in the 1960s.
It is a good question .... fascinating to hear and see this study, as well.
Brandon Howard ... right there with you (I am too new to have an opinion, but I do have one)
The good news is that Oregon did not get ALL of our good soils!
We're grateful for what we did get !!!!
Pendleton, OR...Let'er Buck
13:26 "A study in progress?" Geologist Ned Zinger walks the site of the Milwaukee Road Pacific Extension. The juxtaposition of unimaginable geological time, and a railroad that closed in 1981... punctuated by the thoughtful lone figure of Ned; himself eclipsed by the standing stone, a representation of Gaia and the long years of her existence. Invites us to consider our own place in the continuum, and changes that occur both within and without our lives. ...that'll be $35 million please to any elite who wishes to use art as a vessel to launder money and/or avoid tax.
Anchorage
@NickZentner ( My Vision ) Great to be able to catch-up '!'. My ; Bretz hit a 'screwball' : re- 1924 when he reached < LOC: perry >. He ( Bretz ) , gets 'pinched out' between ; Columbia River , MiS 4+ : Missoula Flood , MIS (Stage 2-4) : Lake Bonneville, MIS 4+. 'TILL ( no pun intended ) next time ... tbc .. ps- battling it out in the corners. pps - ? How far Did the Columbia get re-directed , after getting pushed : CRB's. *A couple of interesting LOC to investigate (1:47:19) Columbia River to the . ? Where are those Leoss hills ? , ?! Swept away from the ~Over-flow~ of the Columbia River ( MIS 4+ ? )
And channels
❤❤❤❤❤ bulldozed older...elevation issues. Self studies.
😎
Pukalani Maui
👍❣
Crazy and fringe is