Relive Important Archive Articles

Waning Pleistocene Ice Sheet Affected Megaflood Paths and Local Shorelines

February 20, 2022

Have you ever thought about the how the weight of the ice-age Cordilleran ice sheet might affect the underlying Earth’s crust. There is strong evidence that the crust was depressed hundreds of feet beneath the ice, and since the crust is relatively thin and rigid over a plastic aesthenosphere, that also caused the crust for some distance beyond the ice margins to tilt toward the ice sheet. A new modeling study explored how changes in topography due to the solid Earth’s response to ice sheet loading and unloading might have influenced successive megaflood routes over the Channeled Scablands between 18 and 15.5 thousand years ago. The modeling found that deformation of Earth’s crust may played an important role in directing the erosion of the Channeled Scabland. Results showed that near 18 thousand year old floods could have traversed and eroded parts of two major Channeled Scabland tracts—Telford-Crab Creek and Cheney-Palouse. However, as the ice-age waned and the ice sheet diminished 15.5 thousand years ago, crustal isostatic rebound may have limited megaflood flow into the Cheney–Palouse tract. This tilt dependent difference in flow between tracts was governed by tilting of the landscape, which also affected the filling and overspill of glacial Lake Columbia directly upstream of the tracts. These results highlight one impact of crustal isostatic adjustment on megaflood routes and landscape evolution. Other studies have shown that relative ice-age sea levels were over 300 feet lower worldwide due to the volume of water locked up in ice sheets. Typical depictions of the shoreface extent are generally based on a 300 ft. depth contour, but there is strong evidence that shorelines were up to 200+ ft. higher than present day in marine areas adjacent to ice sheets, again because the crust was depressed by the weight of the ice sheer. A more accurate representation might show a much narrower shoreface in ice-free areas nearer to the ice sheet margin. However, in the Haida Gwaii Strait at the margin of the ice sheet the lower thickness of the ice sheet meant that local shorelines were as much as 550 feet lower than they are today. This was because the much greater thickness of the center of the ice sheet served to push upwards areas at the edge of the continental shelf in a crustal forebulge. It is now widely thought that these emergent ice-free land areas might have provided a viable coastal migration corridor for early peoples making their way to the Americas from Asia during the Pleistocene.

Grant’s Getaways – Oregon’s Erratic Rocks

June 16, 2016

This episode of Grant’s Getaways features Lower Columbia President Rick Thompson and the Floods-borne erratics of the Willamette Valley

13,000 Year-Old Human Footprints Found on BC Island

March 29, 2018

Big feet. Little feet. A heel here. A toe there. A digitally enhanced photo of a footprint found at Calvert Island, British Columbia that researchers dated to 13,000 years old. Credit Duncan McLaren Stamped across the shoreline of Calvert Island, British Columbia, are 13,000-year-old human footprints that archaeologists believe to be the earliest found so far in North America. The finding, which was published Wednesday in the journal PLOS One, adds support to the idea that some ancient humans from Asia ventured into North America by hugging the Pacific coastline, rather than by traveling through the interior. “This provides evidence that people were inhabiting the region at the end of the last ice age,” said Duncan McLaren, an anthropologist at the Hakai Institute and University of Victoria in British Columbia and lead author of the study. “It is possible that the coast was one of the means by which people entered the Americas at that time.” Dr. McLaren and his colleagues stumbled upon the footprints while digging for sediments beneath Calvert Island’s beach sands. Today, the area is covered with thick bogs and dense forests that the team, which included representatives from the Heiltsuk First Nation and Wuikinuxv First Nation, could only access by boat. At the close of the last ice age, from 11,000 to 14,000 years ago, the sea level was six to ten feet lower. The footprints were most likely left in an area that was just above the high tide line. “As this island would only have been accessible by watercraft 13,000 years ago,” Dr. McLaren said, “it implies that the people who left the footprints were seafarers who used boats to get around, gather and hunt for food and live and explore the islands.” They found their first footprint in 2014. While digging about two feet beneath the surface in a 20-square-inch hole, they saw an impression of something foot-shaped in the light brown clay. In 2015 and 2016, they returned and expanded the muddy pit. They discovered several more steps preserved in the sediment. The prints were of different sizes and pointed in different directions. Most were right feet. When the team was finished they had counted 29 in total, possibly belonging to two adults and a child. Each was barefoot. The researchers think that after the people left their footprints on the clay, their impressions were filled in by sand, thick gravel and then another layer of clay, which may have preserved them. Using radiocarbon dating on sediment from the base of some footprint impressions, as well as two pieces of preserved wood found in the first footprint, Dr. McLaren and his team found them to be 13,000 years old. That would make them the oldest preserved human footprints in North America. “It’s not only the footprints themselves that are spectacular and so rare in archaeological context, but also the age of the site,” said Michael Petraglia, an archaeologist from the Max Planck Institute for the Science of Human History in Germany who edited the paper for PLOS One but was not involved in the work. “It suggests an early entrance into the Americas.” Dr. Petraglia said the footprints also provided strong evidence for the coastal movement hypothesis and he added that they may have traveled the so-called “Kelp Highway,” a hypothesis that underwater kelp forests supported ecosystems down the North Pacific coast that helped ancient seafaring people hunt, develop and migrate. “The work is important because it shows the ‘real’ people, not just artifacts or skeletal remains,” said Steve Webb, a biological archaeologist at Bond University in Australia. “However, the footprints are limited in number and don’t shed light on activities or movement that tell us very much.” He added that future hunts for footprints should keep in mind that not everyone from this time period walked around barefoot. If anthropologists are too busy searching for soles, toes and arches, they might miss clues from those who wore animal skin shoes. Reprinted from New York Times – Earliest Known Human Footprints in North America Found on Canadian Island By NICHOLAS ST. FLEUR, March 28, 2018

23,000 Year Old Human Footprints Found in New Mexico

September 24, 2021

Articles in Science Alert and the New York Times report on a well documented age for many sets of human footprints as old as 23,000 years in the ancient lake shore sands of White Sands, New Mexico. “The footprints were first discovered in 2009 by David Bustos, the park’s resource program manager. Over the years, he has brought in an international team of scientists to help make sense of the finds. Together, they have found thousands of human footprints across 80,000 acres of the park. One path was made by someone walking in a straight line for a mile and a half. Another shows a mother setting her baby down on the ground. Other tracks were made by children.” Beginning in 2019, two United States Geological Survey (USGS) research scientists, Dr. Jeffrey Pigati and Kathleen Springer, began working on the site and found ancient seeds of ditch grass associated with various sets of footprints. The oldest footprints so far have been found in seed beds radiocarbon age-dated as old as 22,800 years, and the youngest footprints dated to about 21,130 years ago. Some scientists still have concerns the seeds might have absorbed older carbon from the lake waters. But in general this research is strongly indicative that humans were present in the Americas long before the generally accepted 15,600-year-old footprint found in Chile or the 13,000 year age of human tools found near Clovis, NM. If humans were well established in New Mexico 23,000 years ago, they must have started spreading down from Alaska long before that. “That starts to wind back the clock,” said Dr. Reynolds of Bournemouth University. Some researchers feel the migration might have been along the coast during the last major ice advance of the Pleistocene, while others argue people could have traveled inland more than 32,000 years ago, before Ice Age glaciers reached their maximum extent and blocked off that route. Regardless of the possible migration route, this new evidence opens up new possibilities that humans may have been present in our local area even before the earliest of the Ice Age Floods, about 18,000 years ago. While the floods could have wiped away most traces of early people in the area, the window of human habitation may be much greater than scientifically documented to date.

Ice Age Floods: A Journey of Awakening – Susan Langsley

July 14, 2018

Do you ever hear the Led Zepplin song “Kashmir” in your head when contemplating the Ice Age Floods? “I am a traveler of both time and space. To be where I have been” –Robert Plant, Led Zepplin’s Kashmir My 11-year old daughter and I are on a 5-day, 4-night raft trip on the Lower Salmon river and we are having the time of our lives! Sun, sand, water, lovely food, games and some of the finest nicest Eastern Oregonians we have ever met. One of the guides is a sensitive and strapping young man who is a student at U of Oregon. He’s both an English major and a Geology major. What do you with that? You write about the soul of the earth, true love and adventure, river stories, deep thoughts that cross scientific paradigms. I see him becoming a teacher someday, maybe a science teacher like his Dad. And he’s a kayaker like me. What is so amazing about the Eastern Oregon guides is their familiarity with, connection to, and love of the river and land. They don’t fight traffic or get on the morning commute treadmill every day. There are no stoplights in the whole of Wallowa County, and the only food franchise is a Subway sandwich shop, no Costco or Walmart. Sure, they have school and work, but they are connected to and love the land they live on in deeper ways that us city folks miss. They are here to tell us about the land. They are guides. The 4th day on the river we pass a group of pillar-like rocks with beautiful symmetry. “That’s columnar basalt” my guide says, “The geologist who figured out the floods and travelled around these parts was J Harlan Bretz”. “J Harlan Bretz” I repeat, carefully, committing to memory. When I returned home to talk to my friend (who was a geology major at Wesleyan) about the trip, she replies “’J Harlan Bretz,’ Oh yes, I have all his books!” An Amazon search and I begin by reading a biography of J Harlan Bretz, “Bretz’s Flood” by John Soennichsen- (some guy from Eastern Washington… hmmm). And guess what: It’s so well-written, I can’t put it down! I am enthralled cover-to-cover with the character of J Harlan Bretz, his teaching method of taking students to the field (and floating them downstream on large Sequoia logs, upon occasion), his love of life, the serendipity of his study of the USGS Quincy Basin topo map when it first published, many summers spent driving around and measuring the Channeled Scablands, presenting his field evidence and theories at the Cosmos Club in Washington DC, and most of all his ability to KNOW he was RIGHT when all his colleagues scoffed and dismissed his theories. Now THAT man was a pillar of strength. Perhaps like a column of basalt? If he were alive today, Harlan Bretz could stand up to money-motivated physicians – the bad kind, nepotism in the school district, gossipers and bullies, and other types of corruption, all of which I have had to do to defend my younger child against since. J Harlan Bretz helped me to do this. He was a GREAT man! “All I see turns to brown.. And fills my eyes with sand as I try not see the wasted land” – Kashmir by Led Zepplin What was it about those floods, biblical in nature, that left behind a story of such jaw-dropping inspiration? Who are these people who live in Eastern Oregon and Washington and are so inspired by the landscapes there they are called to find new ways to study it, publish, write fantastic biographies? I continued my search to find other scholars of the Ice Age Floods, and that led me next to Nick Zentner and Bruce Bjornstadt. To be continued…

Global Human Migration Paths and Timing

May 10, 2018

There is considerable controversy regarding when humans first migrated into the Americas and whether they might have been in the local area during any of the Ice Age Floods. This 2016 video, produced by reputable sources, doesn’t answer that question, but it is an interesting and instructive visualization of human migration paths and timing over the past 200,000 years.

Relive Important Archive Articles

Grant’s Getaways – Oregon’s Erratic Rocks

Global Human Migration Paths and Timing

Like this:

Members

Happenings

About

Resources

Relive Important Archive Articles

Share this article:

Like this: