Whidbey Island glacial deposits

Whidbey Island is a great place to see deposits of several lowland Pleistocene glacial and interglacial sequences, combined with very pleasant beach walks. These  field trips are ideal for winter. It is best to go near the start of an ebb tide- don’t get trapped against a steep cliff of sand and gravel by the flood tide! Use your head and consult tide charts. I’m including UTM grid coordinates for selected places, using the NAD 27 coordinate system. You don’t need them to find your way around, but a number of folks have asked for them on these field trips.

Late-Pleistocene glacial sequence at Whidbey Island Age: 14C or thermoluminescence Whidbey field trip
Fraser Glaciation Everson gmd 10,370-13,010 Blowers Bluff; West Beach*
Vashon till ~15,000 West Beach
Esperance sand (outwash) 18,000 Blowers Bluff
Olympia Interglacial fluvial, lacustrine, peat deposits 22-28,000 Blower’s Bluff
Possession Glaciation glaciomarine drift 70,000 Blower’s Bluff
till Blower’s Bluff
Whidbey Interglacial fluvial, lacustrine, peat deposits ~100-150,000 Double Bluff, Blowers Bluff
Double Bluff Glaciation Double Bluff gmd 175- 200,000 Double Bluff
Double Bluff till

* location not yet visited or written for Northwest Geology Field Trips website.

The trips that comprise this series of field trips will each have there own pages. Click the link to go to each trip.

The first trip visits the lowest sequence of Pleistocene glacial and interglacial sediments on Whidbey, the Double Bluff glaciation and the Whidbey interglacial period which followed.

Part 1: Useless Bay and Double Bluff- Pleistocene strata & earthquake-deformed interglacial sediment

Part 2: Blowers Bluff- Latest Pleistocene glacial and interglacial sediments

8 Responses

  1. Hello

    I own a home on the sand cliff on west beach road, on whidbey island, and am interested in learning more about its geological history, stability and past landslides. There have been several landslides on this cliff in the distant past, and I’d like to learn more about them. I’m also interested in knowing more about the fossils likely to be found in the strata of this cliff.


    • Frank,
      Essentially the entire shoreline of Whidbey Island south of the Deception Pass area is glacial and interglacial deposits. These are inherently unstable. Erosion has created the current shape of the island, as the sea has been gradually whittling away at these bluffs ever since the last ice retreated. It is conceivable to me that someday the entire island could be a thing of the past, though we are talking tens of thousands of years. Rising sea levels would likely increase the erosion rates, as well. There have been many fossil finds in the Whidbey sea bluffs; all are Pleistocene and Holocene animals that roamed the area between glacial advances, or since the last one- mammoths, bears, and the like. There are fossil mammoth tusks and a large bear skull from Whidbey on display in the WWU geology department’s halls.
      I’ll describe that collection in the guide book to Western Washington geology that I’m currently writing for interested laypeople about.

  2. Is the book complete?

    • Loran,
      The book is with the editor. It will come back to me later this winter for necessary revision. It should be available next fall. In time for christmas/chanukkah presents. How’s that for a subtle hint?

  3. Hi Dave,

    I bought Geology Underfoot Western Washington and have particularly enjoyed reading about Double Bluff Whidbey Island (Chapter 11) where I live and beach hike every few days. Thank you for taking the time to create a scale map of the geologic features of the bluff along the beach and provide great graphic label overlays on clear color photos, an amazing and much appreciated educational achievement! I am a member of a group called Sound Water Stewards here in Island County (http://soundwaterstewards.org/web/) and we would be very interested in organizing and hosting you for a beach walk and talk at Double Bluff using your book as a guide and recommended as required reading for the walk.

    Very Best,


    • Albert,
      I can’t take credit for the cross section you refer to on page 169 of Geology Underfoot in Western Washington. The caption gives credit to a paper by K.L. Stoffell. I colored it in and pointed out the geologic features mentioned in the book. As to hosting me on a beach walk for Sound Water Stewards, I’d be very pleased to do that in the fall. I am pretty danged busy for the remainder of the summer.

  4. Did this walk take place? Please include me on a list of contacts if you plan to hold such an event, if the Sound Waters folks will open it up to everyone. I attended a fantastic Mt Baker hike with you, Dave, along with my and my sister’s families a while back, and would be very interested in attending another. My niece is a geology student at UBC and I am certain she would also love to attend.

    • Sara,
      The walk did not get organized by Sound Waters.Any walks I lead that are open to the public are posted to this website’s blog. Subscribers would receive an alert.

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