The Advance and Retreat of the Cordilleran Ice Sheet Revealed in the Bluffs at Discovery Park, Seattle
During his time teaching in Seattle, J Harlen Bretz noted the extensive array of glacial features present in the Puget Sound area. The Puget Lowland is an extensive glacial outwash plain of highly elongated drumlin topography adorned with kames, eskers, kettle lakes, glacial erratics, and other glacial features indicative of continental glaciation. The Seattle Basin is filled with a layer cake of distinctive sedimentary layers that reveal the advance and retreat of the Cordilleran Ice Sheet during the most recent (Wisconsin) glacial advance. South Beach at Discovery Park in Seattle offers visitors an easily accessible exposure of the stratigraphic layers which tell this story. Magnolia Bluff at Discovery Park ranks as one of the most interesting and important geologic sites in the central Puget Sound Lowland. In its near-vertical cliffs, there is a record of the advance and retreat of the last great Ice Age glacier to enter western Washington from the extensive ice fields that covered southwestern Canada. At no other place near Seattle are the geologic relationships of this record so clearly displayed and so accessible to study. The exposure of sediment at Discovery Park is unique in that several distinct layers can be seen in the bluffs during a short walk along the beach. To the inexperienced, the cliff appears to merely consist of a large pile of sand and clay; however, the different layers each tell a story of strongly contrasting environmental conditions over the past 25,000 years. Each of the major beds represents a depositional episode. Their depositional environments can be deciphered by close examination of the composition and texture of each layer of sediment. Sediments comparable to those exposed at Discovery Park are found across Puget Sound, along Hood Canal to the south, and near Tacoma. The large regional extent of these deposits indicates that conditions throughout the central and southern Puget Sound Lowland were similar throughout the time period represented by the deposition of these sediments. A half century of field investigations in the southern Puget Lowland (Armstrong et al., 1965; Crandell et al., 1958; Mullineaux et al., 1965; Noble & Wallace, 1966; Waldron et al., 1962) and in the northern Puget Lowland (Clague, 1981; Easterbrook, 1986, 1994; Troost & Booth, 2008) show that ice sheets have advanced south into the lowlands of western Washington. Evidence for the latest glacial advance can be seen by examining the layer cake of sediments exposed at Discovery Park as the Cordilleran Ice Sheet advanced and retreated over the Seattle area. This recent advance is called the Vashon Stade of the Fraser glaciation. Timeline Prior to 100,000 years ago, the climate in Seattle must have been similar to the climate today. Evidence shows that a river system drained north through the Puget trough. ~100,000 years ago, Earth’s climate began to cool and became more moist. The Cordilleran Ice Sheet began to form in SE Alaska and in British Columbia. ~19,000 years ago, the Cordilleran Ice Sheet advanced to the Canada/US border, sliding at a rate of 135 meters/year. The ice sheet split into two lobes as it passed Victoria B.C. The Juan de Fuca Lobe extended out the Strait of Juan de Fuca, the Puget Lobe extended south over the Puget Sound region. When the ice reached Port Townsend, it blocked the north-flowing river that occupied the Puget Trough, forming a proglacial lake. ~18,000 years ago, ice overrode the lake and covered Seattle. Water was forced to drain to the south through the Chehalis river system. ~16,900 years ago, glacial maximum. The ice sheet extended to just south of Olympia, with ice thickness of ~3,000 feet over Seattle and 6,000 feet over Port Townsend. Sediments visible at Discovery Park Olympia Formation. This is the oldest formation on the exposed bluff wall. The Olympia Fm contains layers of sand, clay, and silt. These beds indicate a fluvial (river) non–glacial environment which existed in the Puget Sound region before the Vashon Stade glacial advance. The sand layers suggest stream deposition, the clay layers suggest ponding, and the silt layers suggest backwaters. There are shallow, broad ripple marks in some of the layers. Radiocarbon dates for wood in the layers at the base of the fm range from 22,000 to 20,000 years BP. A yellowish-gray silt layer 8 m above the bottom of the fm; this 2-m-thick layer contains wood fragments that are 18,000 years old. Pollen in the layers between the base of the Olympia Formation and the base of the overlying Lawton Formation are dominantly spruce and pine, representing a cooler climate than at present. These deposits reflect the climatic conditions in the area before the most recent arrival of ice in Puget Sound. Lawton Formation. The Lawton Fm includes relatively dark clays above the brownish-gray non-glacial sediments. The clays represent deposition in the bottom of a lake which formed in ice margin lakes. The Lawton has striking laminations, which look like varves. The lower portion, which is older, is very fine-grained, which suggests that it was deposited in deep, calm water. The upper part grades into coarser materials and contains ripple marks. The oldest beds of the Lawton Fm are approx, 18,000 years old. Esperance Formation. As the ice front of the Cordilleran Ice Sheet approached Seattle, the size of the deposited particles increased, grading from the clays of the Lawton Formation into the sand layer that we call the Esperance Fm. There are several different layers in this sand deposit, some of which are inclined. The sands are finer at the bottom and coarser on the top. The sands are well sorted, suggesting deposition from glacial meltwater, rather than by ice. The Esperance also contains lenses of gravel within the sand layers. Such lenticular bedding suggests a high energy environment of deposition. Geologically, layers or horizons in a deposit are referred to as “beds”. The orientation of the beds provides clues about the environment when these beds were deposited. The beds in the Esperance Fm show cross bedding. Cross bedding reveals flow direction. Vashon
Unearthing the Secrets of Spokane Valley: A Recap of the IAFI June Jamboree
This year’s IAFI June Jamboree delved into the fascinating geological history of Spokane Valley, contrasting it with the iconic Grand Coulee and Dry Falls, explored during last year’s Jubilee. Challenging the Landscape: Unlike the open spaces of Dry Falls, Spokane Valley presented a unique challenge – showcasing evidence of Ice Age Floods within an urban environment. Our chapter tackled this brilliantly, organizing hikes and car caravans departing from convenient public parks and commercial areas. Evening Explorations: The program’s highlights included captivating lectures. Professor Emeritus Dean Kiefer shed light on J Harlen Bretz’s Spokane associates, while renowned naturalist Jack Nesbit brought the story of the first Columbian Mammoth discovered near Latah Creek in the 1800s to life. Celebrating Success: The Jamboree culminated in a relaxed gathering at Mirabeau Meadows. Registrants, leaders, and participants exchanged insights and experiences, with a resounding appreciation for the chapter’s efforts. Comparisons were drawn, highlighting how our Spokane Valley exploration continued the excellence of the Puget Lobe’s outing at Dry Falls last year. A Delicious Finale: The grand finale was a catered Longhorn Barbecue overflowing with delicious food. Everyone left satisfied, with many even taking home doggie bags to savor the flavors afterward. Check out more images from the event in this Google Photo Album. Meet the Masterminds: Linda & Mike McCollum: This dynamic professor emerita and a research geologist duo co-led tours and car caravans, sharing their latest research on the Spokane area’s Ice Age Floods, and shaping the Jamboree’s theme. Michael Hamilton: A gifted geologist, Michael led hikes and the bus trip, encouraging questions and offering honest answers. Don Chadbourne & Chris Sheeran: Don, the chapter treasurer, managed logistics with expertise, while Chris, our media and registration guru, ensured a smooth experience. Melanie Bell Gibbs: A past president and national board member, Melanie oversaw participant check-in and badge distribution. Dick Jensen: Dick handled bus transportation and provided crucial support throughout the Jamboree. Jim Fox: The chapter vice president secured speakers and offered his assistance wherever needed. We also owe a great deal to the participant volunteers who proved invaluable in assisting us in all our efforts. Through the combined efforts of many the IAFI June Jamboree was a resounding success, fostering exploration, education, and a deeper appreciation for the Spokane Valley’s unique geological heritage. Being present with so much information and conversation among such extensive expertise was to witness the scientific process in action. Meeting people from other chapters was particularly nice, putting faces with names we know. We all learned a lot.
Thank You from Ice Age Floods Institute
Thank you for your Ice Age Floods Institute membership registration and or donation. Your membership dues are used to support public education, research, and public policy advocacy about Ice Age Floods related subjects and issues. Donations are used to support public education, research, and public policy advocacy about Ice Age Floods related subjects and issues unless you have specified a specific purpose for its use. NOTE: Ice Age Floods Institute is a registered 501(c)(3) non-profit organization (EIN 91-1658221), and as such 100% of your membership fees and donations may be tax deductible. This notice confirms that your registration/donation has been submitted, but the transaction is NOT complete until you’ve completed the payment process and you receive a payment confirmation. Please keep confirmation notices as needed for your records.
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IAFI 2023 YEAR-IN-REVIEW
A summary for our members and other interested people By Gary Ford, IAFI President, January 12, 2024 This is our 7th year preparing a Year-in-Review report for you, our members. We appreciate your continued support, friendship and membership. INSTITUTE MEMBERSHIP Our members provide most of our support and much of the reason for the various materials, activities and events we provide. In 1996, we started with 11 members. At the end of 2023, as we continue to recover from the pandemic, we have 648 members (489 memberships) from 20 states, British Columbia, Canada and Germany. INSTITUTE BOARD PROJECTS IAFI work activities occur at both the Institute Board of Director level and at the Chapter level. Projects at the Institute board level generally benefit more than one chapter or do work that all chapters might not be able to do by themselves. Listed below are some of the recent projects the Institute Board of Directors has worked on. The Education Committee is working with a contractor to develop three 20-minute floods videos for a 4th grade audience The Membership Committee is developing a catalog of speakers for the chapters to use for their member programs. A new membership tracking system has been developed which makes it easier to take care of our members. The Trail Advocacy Committee works closely with the National Park Service (NPS) Program Manager for the Ice Age Floods National Geologic Trail. The intent is to help the Trail Manager with projects related to the development of the Trail. We assisted with three NPS Sponsored Teacher Workshops this year: two in the Tri-Cities area and one in Spokane. Website and Newsletter: Our webmaster keeps our website (iafi.org) fresh and stimulating. He also, with support from the chapters, issues the Pleistocene Post Newsletter four times a year. ANNUAL MEMBERSHIP MEETING This year we had our first annual membership meeting and field trip since the pandemic started back in 2020. It was sponsored by the Puget Lobe Chapter with major assistance from the Lower Grand Coulee Chapter and was held in the Sun Lakes State Park area. Click here for a summary. 2023 CHAPTER PROGRAMS Outreach to inform and educate the public about the Ice Age Floods and their long-lasting impact on our area is a key part of the IAFI mission. Our local chapter programs are possibly the most effective way we meet this challenge. Three of the more important ways we help people learn about the Ice Age Floods are with lectures, field trips and hikes. Lectures – As we have moved beyond the pandemic, we have been able to again offer more in-person lectures with some viewed Zoom presentations. We had 50 in-person lectures attended by over 1642 people. Many more people viewed these lectures when they were posted on YouTube. Field Trips – We conducted 21 field trips with 586 attendees. Hikes – Three chapters sponsored 13 hikes with 163 attendees. CHAPTER PRESENTATIONS TO SCHOOL GROUPS AND SCIENTIFIC ORGANIZATIONS Lake Lewis Chapter: A number of people from the Lake Lewis Chapter help with education programs at The Coyote Canyon Mammoth Site (MCBONES) near Kennewick. Between April and October 2023, McBones hosted school classes or home school groups on 58 days, participated in 12 STEM (Science/Technology/Engineering/Math) events at elementary, middle and high schools, conducted 40 group tours, hosted 12 public tours, and did 7 youth group tours. That means that 1853 adults and 2242 kids were exposed to the story of MCBONES’ Coyote Canyon Mammoth Site and the ice age floods in 2023. Each presentation included the story of the floods usually including the IAFI map of the floods region. The connections between the floods and the mammoth are that the mammoth was buried in several layers of floods sediment (Touchet beds). There are erratic pebbles buried among the bones and the elevation of the bone bed is just over 1000 feet above sea level (about 650 feet higher than the Columbia River at the Tri-Cities). The calibrated radiocarbon date of death of the mammoth is approximately 17,449 years before present. We are studying the death and burial of a Columbian mammoth. We can’t tell people about that without including the floods story. This is a “Who Done It” story, and we have a suspect. Cheney-Spokane Chapter gave a talk to 84 sixth graders at Jefferson Elementary School in Spokane, WA. Also, conducted a program at STEM in March with 367 students. Glacial Lake Missoula Chapter helped with a Bozeman Science Camp. Had a day of classroom activities that discussed glaciers, ice ages, landscapes, climate change. Field trip day featuring Lake Missoula impacts to modern landscapes. Palouse Falls Chapter hosted the Geological Society of Oregon Country for three lectures and three days of touring about 600 miles of the channeled scablands. Had an information booth at STEAM (Science/Technology/Engineering/Arts/Math) night at Colton School. Lower Grand Coulee Chapter assisted with a geology presentation at the Ice Age Floods Fest at Dry Falls aimed at educating children on the Ice Age Floods story (350+ attendees) CHAPTER PRESENTATIONS AT COMMUNITY EVENTS Cheney-Spokane Chapter talked with 102 people at Spokane Outdoor Expo. Talked with 128 people at the Blue Waters Bluegrass Festival, Medical Lake, WA. Glacial Lake Missoula Chapter presented program to Five Valleys Land Trust banquet. Took Wildlife Film Festival Film makers on eastern loop. Featured lake Missoula Story at all stops. Featured Glacial country scenery shots. Columbia River Gorge Chapter made presentations to visiting Polish and German Marshall Fund delegations and led donated field trips for Bingen-White Salmon Rotary and Skyline Health Foundation. Lower Grand Coulee Chapter had a booth at the Quincy Farmer Consumer Awareness Day with IAFI talks and tours, videos and information displays. 250+ attendees. Palouse Falls Chapter conducted a tour at the Sandhill Crane Festival, had a booth at both the Wheatland Fair and the Palouse Empire Fair. Wenatchee Chapter participated in FCAD Farmer Consumer Awareness days in Quincy; also made a presentation at a Master Gardener Conference, 89 attendees. CHAPTER MEMBERSHIP APPRECIATION EVENTS Our members
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IAFI Booth at WSTA-CSTA Conference in Wenatchee
Ken Lacy of the IAFI Wenatchee Chapter hosted an information booth at the 2022 Washington Science Teachers Association Conference on Oct. 14-15 in Wenatchee, WA. His was the first use of a new table-top display that we recently developed for conferences, meetings and conventions. Ken felt the display,with its impressive graphics, showing maps and images of Ice Age Floods features, attracted a lot of interest and attention and fostered great opportunities to further engage with the conference goers as they came in for a closer look. He felt there was a high level of interest in the Ice Age Floods topic and people were keen to learn more about the floods, which led to many good conversations. It also gave Ken and opportunity to talk to as many as 10 ESD Science Coordinators about our project to provide 4th Grade level education materials about the Ice Age Floods. Their response was uniformly that this idea would not be well received because there was no time available for additional non-formulary classes. One of these Science Coordinators suggested it might be possible to combine our Floods program with an existing program, such as Language Arts, by presenting Floods information and having the students “prove” the existence of the floods by listing facts that supported this hypothesis. In another discussion with a retired school administrator about the issue of available time for our 4th Grade Floods program, she cited two examples of havin had to turn down outside offers of valuable educational programs because there was just not enough class time available for those programs. However, when Science Coordinators and teachers were asked about the idea of having IAFI people either conduct classes themselves or help the teachers develop such a class, the response was quite positive. The different response to the idea of our 4th Grade Floods program and the proposal for individual classes is significant in terms of class-time and preparation required. A single class session can often be fit into the schedule, but a multi-class program may cut too deeply into the time needed for required cirricula. Still, there are several sections in the Washington State Fourth Grade Curriculum that can support the inclusion of our proposed Ice Age Floods program. It will therefore be necessary for IAFI to work with the ESD Science Coordinators in each school district to get their support for the inclusion of our project.