Must See Floods Features in Northern Idaho
SOME LOCAL NORTHERN IDAHO ICE AGE FLOODS and GLACIAL FEATURES Purcell Trench – This structurally formed valley became the passageway for the Purcell Ice Lobe that divided into five glacial sub-lobes. The east moving sub-lobe blocked the Clark Fork River forming Glacial Lake Missoula, the source of the Ice Age Flood waters. Other sub-lobes modified and deepened the basin now occupied by Lake Pend Oreille or helped define several important N-S transportation routes. The Purcell Trench is visible from City Beach in Sandpoint and Schweitzer Mountain Rd. Hwy 95 follows the Purcell Trench from Sandpoint to beyond Bonners Ferry. Cabinet Gorge – Contact of Pleistocene Ice and Glacial Lake Missoula Water – Although the contact of the Pleistocene Ice and the lapping waters of Glacial Lake Missoula was in flux as the glacier advanced and retreated, the Cabinet Gorge is considered by many to be a likely location of the terminus of the Clark Fork sub-lobe that blocked the drainage of the Clark Fork River. Evidence of glacial erosion and till deposits indicate glaciation; however, flood deposits on the south side of the river attest to Ice Age flooding. Cores taken during the construction of the Cabinet Gorge Dam suggest multiple stages and events of ice damming. An AVISTA maintained viewpoint at the Cabinet Gorge Dam with Ice Age Floods signage provides an excellent location to ponder the formation and disintegration of the ice plug blocking the Clark Fork River. Glacial Striations – Striations can be viewed along Hwy 200 east of Hope and on the south side of Castle Rock east of Clark Fork. Glacial/Flood Related Erratics – Large and small erratics cover the glacial and flood modified landscape. Large erratics can be seen along Hwy 200 east of Clark Fork, in Sandpoint’s City Beach and in Farragut State Park. A large pile of erratics excavated from flood deposits are visible on the west-side of Hwy 95 south of the Hoodoo Channel. A giant ice-rafted flood related erratic weighing over 1,600 tons is located on the east-side of Hwy 41 near Twin Lakes. Lake Pend Oreille – Cross-section morphology, depth, and sediments – This is where it all started! Lake Pend Oreille is the largest lake in Idaho and the deepest lake in the Pacific Northwest and the 5th deepest in the US. The lake level is 2062 ft above sea level with depths over 1,000 feet and an additional layer of over 1,500 feet of glacial-fluvial deposits going to bedrock, with the surrounding terrain as high as 6002 ft. The glacially modified U-shaped bedrock valley, cut to approximately 600 feet below sea level, was formed by the Pend Oreille glacial sub-lobe. This glacial sub-lobe was up to 4,000+ ft. thick and 30+ miles wide. It was the ice plug responsible for blocking the Clark Fork River. It collapsed catastrophically as often as about every 10-60 years, releasing 40-100 Ice Age Floods. The location of the lake is probably related to an old river valley controlled by faults. The Lake Pend Oreille basin was carved by the repeated advances of Pleistocene ice and scoured by ice age floods. With the waning of ice age flood waters, the basin was, and continues to be, filled with glacial outwash and flood deposits. The lake is dammed at the south end by thick glacial and flood deposits the mark the beginning of the “Outburst Deposits”. There is a pullout on Hwy 200 approximately one mile west of Hope with signage already established that provides a great view looking south across Lake Pend Oreille to the Green Monarch Mts. Another view of the former ice plug location along Hwy 200 is the mouth of the Clark Fork River at the Clark Fork Drift Yard. Giant Current Dunes or MegaRipple Marks – One of Bretz’ most important pieces of evidence for catastrophic flooding was the “giant current dunes.” These large-scale bedforms appeared as patterns of parallel ridges and swales on many aerial photographs in the flood channels in the scabland of Washington, but had escaped recognition from the ground because of their size. Giant Current Dunes are visible west of Clark Fork near Castle Rock; however, the most prominent and visible Giant Current Dunes are located several miles east of Spirit Lake along Hwy 54 where the highway cuts through the dunes showing their undulating profile. The location of many of the telephone poles on the crest of these dunes accentuates these landforms. The dunes form transverse to the current direction, and form cusps that are convex upstream, with arms that point downstream. Furthermore, the size of the cusps appears to decrease in the direction of lower velocity. Internally, the dunes consist of gravel and pebble foresets. Giant current dunes exhibit an asymmetrical profile with the downstream (lee) slope steeper than the upstream slope. Crests range from 20 to 200m apart and heights range from 1 to 15m (Baker and Nummedal, 1978) and are among the largest measured throughout the Floods area. The Spirit Lake current dunes can also be easily recognized from the air by their characteristic pattern, accentuated by vegetation. This dune field is immediately in the path of the breakout from Lake Pend Oreille, and experienced some of the highest energy flows. Rhythmites – Rhythmites are glaciolacustrine sediments associated with flood events and are useful in attempting to determine the number of Ice Age Floods. A 112-foot cross-section of rhythmites is located at the junction of East Fork Creek and Lightning Creek approximately 6.5 miles northeast of Clark Fork along Lightning Creek Road (NF-419). Proglacial Deposits – This type of deposit is found associated with most of the drainages on the south side of the Clark Fork Valley and extend from the mouth of the Clark Fork River to nearly Thompson Falls in Montana. These sediments are glacio-fluvial deposits deposited in contact with the ice and therefore provide evidence of glaciation in the Clark Fork River drainage. The associated geomorphic features formed by these deposits are referred to as “kame deltas”. The gravel pit associated with Dry Creek (approximately 8 miles west of Clark Fork
The Oldest Stone Tools Ever Found in the US
Indigenous people have been in the Americas longer than archaeologists once thought. Stone tools unearthed from a rock shelter in Southern Oregon were last used more than 18,000 years ago, radiocarbon dating suggests. That makes the site one of the oldest-known human living spaces in the Americas. Buried deep beneath a layer of volcanic ash, archaeologists excavating Rimrock Draw Rockshelter found two stone scraping tools, which ancient knappers had skillfully shaped from pieces of orange agate. A residue of dried bison blood still clung to the edges of one scraper, a remnant of the last bit of work some ancient person had done with the tool before discarding it. The layer of volcanic ash above the tools had blasted out of Mount St. Helens, a few hundred kilometers north of the rock shelter, 15,000 years ago, long after the fine agate scrapers, and the people who made and used them, had been forgotten. In a layer of dirt below the volcanic ash but above the stone tools, archaeologists found broken teeth from now-extinct relatives of modern camels and bison. Radiocarbon dating on a piece of bison tooth enamel (first in 2012, and confirmed recently by more testing) suggests the teeth belonged to animals that lived about 18,250 years ago. And because those teeth were buried in a layer of dirt above the stone tools, they must have ended up in Rimrock Draw sometime after the tools. That makes the agate scraper, complete with bloody evidence of its use, more than 18,000 years old—and one of the oldest traces of human presence in North America. But the people who lived in Oregon more than 18,000 years ago almost certainly weren’t the first to call the continent home. In Idaho, the Nimiipuu (Nez Perce) know the Cooper’s Ferry archaeological site as the ancient location of a village they call Nipehe. The oldest artifacts unearthed at the site date to at least 16,000 years ago, and it looks like people lived there, at least off and on, for several thousand years after those first arrivals. To have reached Cooper’s Ferry 16,000 years ago, the ancient inhabitants of Nipehe would have had to cross Beringia, a land mass that connected what’s now Russia with what’s now Canada during the last Ice Age, when sea levels were lower. They then had to move south along the Pacific Coast of North America, skirting along the western edge of the great ice sheet, until they reached the southern edge of the ice. The ice-free corridor wouldn’t open until about 15,000 to 14,000 years ago. By then, people were already living far, far south of the ice: Archaeologists found stone tools and butchered mastodon bones submerged in a Florida sinkhole that dated back to 14,500 years ago. And in Chile, someone left behind a single footprint 14,600 years ago. Thanks to footprints on an island off the coast of what’s now British Columbia, we know that at least some people did make their way along the coasts about 13,000 years ago. But some archaeologists, like Bournemouth University’s Matthew Bennett and his colleagues, say that those coastal migrants may have found their way into a continent already home to people who arrived at least 26,000 years ago—long before the ice sheets blocked the way into North America from Asia. In the mountains of north-central Mexico, archaeologists unearthed stone tools from Chiquihuite Cave, which dated back to around 30,000 years ago. And at White Sands National Monument in New Mexico, it appears that someone walked along the ancient shoreline of Lake Otero (now long since dry) between 23,000 and 21,000 years ago, leaving behind a trail of 61 footprints. Archaeologists dated the White Sands footprints thanks to grass seeds trapped in the layers of clay and silt above and below the tracks, which helped bracket their possible age. Some archaeologists are still skeptical, partly because there are so few sites this old south of the ice sheets, but there’s enough evidence to take the claims seriously. Taken from an article by KIONA N. SMITH published in arsTechnica
Modeling Time: Human, Geologic, Cosmologic
It’s difficult for most people to grasp the immensity of time as it’s viewed by archeologists, much less as it’s viewed by geologist or cosmologists. One way often used by those scientists to model time in terms that others can visualize is to compare time to distance along a path, with markers to denote specific events and periods. To Scale: TIME is a YouTube video about a group of friends who built a practical scale model of time: 13.8 billion years of cosmic evolution, and our place within it, on a dry lakebed in the Mojave.
Molten Mush Under Yellowstone Supervolcano
The mantle hotspot now under Yellowstone is thought to have been the source of the voluminous Columbia River Basalts that erupted from 17 to 6 million years ago as the North American continent passed over the hotspot, and that now underlie much of the path of the Ice Age Floods. During and since that time the hotspot cut a long and explosive path from the Oregon/Nevada/California border across the Snake River Plain, but ongoing research appears to show it to be fairly stable for at least our brief geologic time. A new study has found the amount of melted rock beneath Yellowstone’s supervolcano is far higher than previous estimates. Scientists have worked out the consistency of the magma under the Yellowstone caldera using seismic waves — and the reservoir is filled with “mush” that doesn’t pose an imminent eruption threat. While researchers say there is no sign of an imminent eruption, the discovery provides a more detailed view of what’s going on in the enormous magma chamber that sits beneath the national park. Far from a smooth blend of molten rock, magma reservoirs contain a large amount of solid rock, semi-liquid crystals, gasses and other volatile substances. This “magmatic mush” is highly dynamic but tends to burst out from deep underground when the proportion of liquid — or melt — crosses a certain threshold. Previous work suggests that eruptions typically occur when at least 50% of the space in the upper magma reservoir — a layer of flattened pockets of magma stacked on top of each other — is filled with melt. The magma reservoir beneath Yellowstone volcano consists of two chambers — a shallow reservoir near the surface that’s around 55 miles (90 kilometers) long and 25 miles (40 km) wide, and a deeper chamber that is about 4.5 times larger. While the deeper reservoir contains about 2% melt, the upper chamber contains far more: A study published in Science in December 2022 put the proportion of melt between 16% and 20%. Now, Sin-Mei Wu, a geophysicist and postdoctoral researcher with the Swiss Seismological Service at the Federal Institute of Technology (ETH) in Zurich, and colleagues have found the percentage is much higher. The team used seismic wave data to assess the texture and composition of the upper magma reservoir, which is about 3 miles (5 km) deep at Yellowstone. The results, published June 8 in the journal Earth and Planetary Science Letters, indicate the upper chamber consists of 28% melt — 8% to 12% more than the 2022 estimate, which was found with different methods, Wu said. “What we found is that the portion of liquid phase is not enough to have an imminent eruption,” Wu told Live Science. “Although we found a much higher portion of liquid than what was previously found, it’s still only up to 28%. So, to the best of our knowledge, Yellowstone will not have an imminent eruption.” Working out the proportion of liquid in magma reservoirs could help scientists evaluate the risk of volcanic eruptions elsewhere. “It’s important to understand the eruption potential, maybe not for Yellowstone so far, but you can apply the same methods to other magma systems that are more prone to eruption and to some that are already erupting,” Wu said. The methodology used for the study is “revolutionary in the detail and resolution it allowed for,” said Michael Poland, a research geophysicist and scientist-in-charge at the Yellowstone Volcano Observatory. The magma at Yellowstone and in other magmatic systems is like “mush,” Poland told Live Science in an email. “We often refer to ‘magmatic mush’ to convey a sense that it’s not a 100% molten ball, but also contains a lot of solid material — in the case of Yellowstone, way more solid than liquid material,” he added. “Maybe like a really thick lentil soup.” Despite recent breakthroughs, scientists can’t be sure what exactly lurks beneath the supervolcano, Wu said. “We are looking forward to some joint interpretation with other geophysical data to find out, for example, if we only have melt or if there is gas, volatiles, or something else that will help us understand the eruption dynamics.” From an article in Live Science by Sascha Pare
Why Did The Last Ice Age End?
Nearly 10,000 years ago, Earth came out of its most recent ice age. Vast, icy swaths of land around the poles thawed, melting the glaciers that had covered them for nearly 100,000 years. Why, after such a long period of cold, did the ice age finally come to an end? Scientists are still searching for the answer. The traditional explanation — and short answer — for why ice ages begin and end is a series of eccentricities and wobbles in the planet’s orbit known as the Milankovitch cycles that describe patterns in Earth’s orbit and axial tilt. Over time, our planet’s orbit around the sun alternates from being more circular to more egg-shaped. At the same time, our planet’s axis tends to both tilt and wobble. Milankovitch found that these factors combine at regular intervals to cause land at 65 degrees north latitude (a parallel that runs through Canada, Alaska and parts of Eurasia) to become warmer than normal and theorized that this warming and then subsequent cooling of the Northern Hemisphere explained the planet’s cycle of ice ages — or glacials — and warmer periods — or interglacials. But this doesn’t explain why the ice ages ended in the Southern Hemisphere about the same time. One alternate explanation is that when the Northern Hemisphere began to warm around 13,000 years ago, meltwater and icebergs flooded the North Atlantic Ocean, causing a temporary cooling of the Northern Hemisphere known as the Younger Dryas period (12,900 to 11,700 years ago). There is some evidence that the Younger Dryas affected ocean currents in a way that caused the Southern Atlantic to warm up, stirring up the ocean in the process and releasing tons of stored carbon dioxide into the atmosphere, which in turn caused glaciers in the Southern Hemisphere to melt over the next 1,500 years. The end result was likely a more carbon-rich atmosphere that continued to warm both hemispheres, lifting the planet out of the glacial period. Another hypothesis, published in 2021, suggests that the length and intensity of the Southern Hemisphere’s winters could dictate when ice ages end. On the surface, it sounds like the polar opposite of the Milankovitch theory, which suggests that Northern Hemispheric summers drive the climatic changes. However, long winters in the Southern Hemisphere alter wind patterns near the tropics, which can create frequent storms over an area of the Pacific Ocean known as the Tropical Warm Pool — a region of ocean that stores and releases great amounts of heat. Altered winds can create storms in this area, which in turn releases massive amounts of water vapor that can act as a greenhouse gas. Another idea is that salty water pouring from the Indian Ocean into the Atlantic Ocean helped end the last ice age. The Indian Ocean had become super salty because a drop in sea level had cut off a critical current that flows from the Pacific to the Indian Ocean; normally, this current diluted the Indian’s very salty tropical waters. A change in wind patterns and currents in the Indian Ocean could have caused the Indian Ocean to dump tons of dense, salty water into the Atlantic Ocean, altering its currents and temperatures in both the Northern and Southern hemispheres. More evidence is needed to know for sure if any of these hypotheses can actually explain why the last ice age ended. But glaciologists are continuing to look into this cold case From a June 23, 2023, Live Science article by Cameron Duke
Lyle Cherry Orchard Trail Geology Recording
The Lyle Cherry Orchard Trail is a moderately strenuous trail being developed in the Columbia Gorge by Friends of the Columbia Gorge. They envisioned having a number of interpretive stations along the trail to inform and educate trail users. A station could focus on a single topic, such as the geology, plants, animals, indigenous and cultural history of the area. But they found that the cost of interpretive signs would be prohibitive, would be expensive to maintain and might not last long. So they started brainstorming for better ways to realize thier vision. The came up with a plan to place trailside posts, resembling basalt columns, with a QR code the user could scan with their smartphone that would connect to an informative recording about that location. Friends hopes to have the trail work and information stations finished by 2024. Then everyone will be able to experience the beauty along the Lyle Cherry Orchard Trail with a deeper understanding of their surrounding through the recordings. Renee Tkach, a Friends coordinator of the project, contacted Lloyd DeKay, president of the IAFI Columbia Gorge Chapter, about doing a recording for the first station about the geology of the area. They took a very windy hike together on the still somewhat challenging trail to the first station, where they talked about the focus of a recording and took a number of photos to document the views. At home Lloyd developed a script that everyone reviewed and agreed upon. Then began a few frustrating hours of recording and editing to produce a 4:30 minute recording. Since the original plan was for a 3:00-3:30 minute recording, Friends will now review the recording and decide if it’s OK or needs to be shorter and where to cut back. This method may also be an easier, economical and useful way to provide information at other floods sites throughout the region. Significant advantages include the relatively low cost and long life of the information station, and ability to provide both video and audio clips for a number of features on a webpage linked to the QR code, and the ability to modify and update the presentations as new or updated information becomes available.
Outburst Floods GSA Penrose Conference Visits West Bar
The 2023 GSA Outburst Floods Penrose Conference made a field trip stop on Tuesday afternoon, June 6, at Ken Lacy’s (IAFI Wenatchee Valley Erratics Chapter member) home, for a spectacular overview of the West Bar Current Megaripples that can be seen well from that vantage point. The 75 conference attendees were all at the conference by invitation only. They were accompanied by organizers Jim O’Connor, Isaac Larsen, Joel Gobiner, Vic Baker, Richard Waitt, Jerome Lesemann. The purpose of the conference was to review the current outburst floods fieldwork being done, encompassing the range of science conducted both on Earth and elsewhere in the solar system. The timing of the conference coincided with the 100th anniversary of J Harlen Bretz’s first publication on the Channeled Scabland, and took place at Camp Delany, which occupies a spectacular flood-carved setting at the foot of Dry Falls in Grand Coulee, Washington. The conference was meant to review past and present work, as well as help chart the future science on outburst floods through presentations, discussions, and multiple field trips. Everyone who shared Ken’s hospitality were in particularly good humor, as considerable amounts of cookies, popsicles, and bottled water were consumed. There were many comments about how well the meeting was going and how lots of new insights were being discussed. These kind of comments suggest that the meeting was being extremely well received. Ken was also pleased to talk to Justin Radford, along with his USGS Research Geologist… nice to see them in attendance.
Sea levels from the Maximum of the Last Ice Age to the Present Day
The Wenatchee Valley Erratics’ next program will be on Tuesday, June 13 at 7:00 PM at the Wenatchee Valley Museum and Cultural Center, 127 South Mission St., Wenatchee. Erratics’ member Kirk Laird will talk about “Sea levels from the Maximum of the Last Ice Age to the Present Day.” His presentation will focus on information directly available from NOAA’s Tides and Currents Office, and from NOAA’s Office of Satellite Altimetry. The 400 foot change in sea level over the last 22,000 years is directly attributable to the melting of continental and montane glaciers. With degrees in both Geology and in Oceanography, Kirk has observed earth science issues his entire life. And for the last 25 years, he has paid very close attention to the status of the oceans, in particular. This is a hybrid meeting. You can attend in-person at the Museum. Or you can participate via a Zoom link: https://us02web.zoom.us/j/84520197937 Please sign in at 7:00 PM, June 13! The program is free and open to the public.
Some Ice-Age 1st Peoples in Americas Came From China
The first wave of humans into the Americas during the last ice age may have hailed partly from northern China, according to a DNA study of ancient and modern Indigenous people. The ancient groups may have also migrated to Japan, potentially helping explain similarities in Stone Age artifacts in the Americas, China and Japan, according to the study, published Tuesday (May 9) in the journal Cell Reports. There are two leading models as to how people first migrated to the Americas. The older idea suggests that ancient Siberians made this journey when the Bering Land Bridge — the landmass that once connected Asia with North America — was relatively free of ice. More recent evidence argues that multiple waves of humans journeyed to the Americas from various parts of Eurasia, perhaps on watercraft along the Pacific coasts of Asia, the Bering Land Bridge and North America. To shed light on the origins of Indigenous Americans, scientists examined DNA from mitochondria, the powerhouses of the cell. Mitochondria possess their own genes, which are passed down from the mother. The new findings suggest that the ancestors and closest relatives entered the Americas through at least two migrations. Both diasporas apparently occurred when the land bridge from Asia to the Americas was obstructed by ice, so the researchers suggest that ice age people may have traveled via the Pacific coast instead. The first migration likely happened between 19,500 and 26,000 years ago, during the Last Glacial Maximum, the coldest part of the last ice age, the researchers said. Back then, ice sheets covered much of the planet, and living in northern China would have likely proven difficult for humans. The scientists estimated the second event apparently occurred between 19,000 and 11,500 years ago, when the ice sheets began melting. Prior work suggested this climate shift likely helped support the rapid growth seen in human populations during this era, which may have helped drive their spread into other regions. In all, the new study “matches well with what we know about the archaeological record of Japan, and lends weight to current models of how humans came to populate the Americas,” Loren Davis, an archaeologist at Oregon State University in Corvallis who did not take part in this research, told Live Science in an email. This discovery may help explain some archeological similarities that prior work controversially suggested at times existed between Stone Age peoples in China, Japan and the Americas. Specifically, researchers had argued the three regions possessed similarities in how they crafted “stemmed projectile points” for arrowheads and spears. However, while the new study is exciting, it’s just “another piece of the puzzle,” on how and when ice age humans first populated the Americas, Davis said. For instance, the researchers stressed that while these new findings suggest this single northern Chinese lineage may have contributed to Indigenous American ancestry, “it does not represent the whole history of all Native Americans,” Li said. “Investigating other lineages showing genetic connections between Asia and the Americas will help obtain the whole picture of the history of Native Americans.” For more details read the whole article by Charles Q. Choi at Live Science
How do we know how old Earth is?
By measuring radioactive elements in rocks from Earth and other parts of the solar system, scientists can develop a timeline of our planet’s early years. Earth is roughly 4.54 billion years old. In that time, it has seen continents form and disappear, ice caps expand and retreat, and life evolve from single-celled organisms into blue whales. But how do we know Earth’s age? We start by looking inside it. “When you’re an Earth scientist who looks at a rock, it’s not just a rock; it’s like that rock has a story that you can try to decipher,” said Becky Flowers, a geologist at the University of Colorado Boulder. When minerals form out of magma or lava, they often contain traces of radioactive material, such as uranium. Over time, those radioactive elements decay, meaning they spew radiation, eventually transforming them into new, more stable elements that remain trapped inside the mineral. Take radioactive uranium-238, a common form of uranium. Its atoms will release energy until they eventually turn into lead. That process occurs at a fixed rate known as a half-life, which corresponds to the amount of time it takes for half of the atoms to decay. The half-life of uranium-238 is more than 4 billion years, meaning it takes more than 4 billion years for half of the uranium-238 in a sample to become lead. This makes it perfect for dating objects that are very, very old. By knowing these half-lives, we can calculate how old a rock is based on the ratio of the “parent” radioactive element and the “daughter” stable element — a method called radiometric dating. The mineral zircon is commonly used for radiometric dating because it contains a relatively large amount of uranium, Flowers said. Uranium-lead dating is just one type of radiometric dating. Other types use different elements; for example, radiocarbon dating, one of the most common methods, uses a radioactive isotope of carbon that has a half-life of thousands of years and is useful for dating organic matter. Using these methods, geologists have found minerals on Earth that date as far back as 4.4 billion years, meaning the planet has been around at least that long. But if scientists say Earth is more than 4.5 billion years old, where did those extra 100 million years or so come from? Earth, as mentioned, has changed a lot over billions of years, especially through processes such as plate tectonics, which shift the crust, birthing new land out of magma and subducting old land back underground. As a result, rocks from the very beginning of the planet’s history are hard to find; they’ve long since eroded or melted back into raw material. But scientists can use radiometric dating to determine the age of rocks from other parts of the solar system, too. Some meteorites contain materials that are more than 4.56 billion years old, and rocks from the moon and Mars have also been dated to around 4.5 billion years ago. Those dates are pretty close to the time scientists think the solar system started to take shape out of the cloud of gas and dust surrounding the newborn sun. And by knowing all of these relative ages, we can start to piece together a timeline of how Earth, the moon, Mars and all of the other little rocks floating around in nearby space started to form. Yet the transition from primordial dust cloud to planet Earth didn’t happen all at once but rather over millions of years, Rebecca Fischer, an Earth and planetary scientist at Harvard University, told Live Science. That means our understanding of Earth’s age will always be less about a specific year when the planet formed and more about a general sense of the era when our home planet started to take shape. By Ethan Freedman (lifes-little-mysteries ) reprinted from LiveScience.com