Hayden: Dating Erratic Boulders: How Long Ago Were the Floods?
2026-07-07 13:00 - 13:30 (America/Los_Angeles) | Hayden Library, 8385 N Government Wy, Hayden Lake, ID, 83835
How do geologists know when the ice age floods actually occurred in the Spokane area? One method is to date the large flood-rafted erratic boulders. We explore the ages of the floods and the methods used to determine their dates and present newly gathered dates from the Spokane region revealing when the floods happened.
Presented by Glenn Cruickshank, vice president of the Ice Age Floods Institute (IAFI), Cheney-Spokane Chapter, and Dr. Jim O’Connor, USGS
Registration is required. It will be linked here as soon as it has been posted to the library website.

Rathdrum: Dating Erratic Boulders: How Long Ago Were the Floods?
2026-07-14 15:00 - 16:30 | Rathdrum Library, 16320 ID-41, Rathdrum, ID, 83858
How do geologists know when the ice age floods actually occurred in the Spokane area? One method is to date the large flood-rafted erratic boulders. We explore the ages of the floods and the methods used to determine their dates and present newly gathered dates from the Spokane region revealing when the floods happened.
Presented by Glenn Cruickshank, vice president of the Ice Age Floods Institute (IAFI), Cheney-Spokane Chapter
Registration is required. It will be linked here as soon as it has been posted to the library website.

Spirit Lake: The Ice Age Missoula floods and the Spirit Lake giant current dune field
2026-07-21 13:00 - 14:30 | Spirit Lake Library, 32575 N 5th Ave, Spirit Lake, ID, 83869
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.
Presented by Dr. Linda McCollum, president of the Ice Age Floods Institute (IAFI), Cheney-Spokane Chapter
Registration is required. It will be linked here as soon as it has been posted to the library website (https://communitylibrary.net/library/spirit-lake/).

Bretz Was Right: A Pre‑Birthday Floods‑Fest
2026-08-29 10:00 - 14:00 | OR
Save the date!
Our chapter is planning a special late‑summer gathering on Saturday, August 29, in honor of J Harlen Bretz, whose birthday falls just a few days later (September 2). Bretz’s groundbreaking work on the Ice Age floods reshaped the scientific understanding of the Northwest—and we think that deserves a celebration.
We’re still shaping the details, but expect a relaxed, community‑friendly event that highlights Bretz’s legacy and the remarkable landscapes he helped the world understand. More information will be posted as plans develop.

He mapped the scablands bold and bright,
Said “Floods did this!” with all his might.
For thirty years they told him “No”…
’Til evidence began to flow.
So join us as we celebrate
The man who made the floods make sense —
A pre‑birthday bash for J Harlen Bretz,
Who proved the skeptics wrong (immense!).
