Video – Glacier retreat in Puget Sound

Also land rebound …but something here doesn’t make sense to me

From glaciers to volcanoes to earthquakes, witness the processes that have shaped the Puget Sound landscape.

When you first click on this video, it will appear that nothing is happening.

But look at the bottom left side of the video to see the year scrolling by.

Video by Burke Museum

Something here doesn’t make sense to me.

Notice that the ice extended south of Olympia about 17,000 years ago. Then, as the ice melted, Puget Sound waters extended almost to Olympia. Then, as the glaciers continued their retreat, the water also retreated.

Knowing that sea levels were 400 feet lower than today at the height of the last ice age, I thought we should see Puget Sound growing bigger as sea levels rose. Is the Burke Museum trying to tell us that the land rose (rebounded) by 400 feet?

I have visited the Burke Museum many times and have the utmost respect for them. Perhaps someone else can shed light on this? Did the land around Puget Sound actually rebound by the height of a 40-story building?

Thanks to Oly for this video

“Ice was 3000 feet deep here where I dwell,” says Oly.


20 thoughts on “Video – Glacier retreat in Puget Sound”

  1. I found a spear head in downtown Tacoma on a construction project and took it to the Burke Museum artifact ID day and they told me it’s 5000 years old.
    That’s old school.

    Reply
  2. I live in Westchester County, NY. The Laurentide glacier covered Westchester and NYC to the South as of 13000 BC, pushing the land down by hundreds of feet. South of NYC, the land rose, on what is now the Continental Shelf. The Hudson River carried glacial melt water and silt south to the Atlantic, and in the process cut a deep canyon now called the Hudson Submarine Canyon. As the glaciers retreated, the salt water advanced North until New England became an island. The land gradually rose, and the bare rock was covered with red clay silt from the Hudson River. Eventually the land rose above the level of the Hudson, and became forest.

    Reply
  3. I can’t speak to Puget Sound, but I know they say the same thing happened, and is happening around and under Lake Michigan.

    Reply
  4. Greetings, a few years ago there was a Nat Geo program on the last Cascadia Fault rupture… about the time of the Japan earthquake and tsunami. The geologist leading the taping of the show, went to Puget Sound and found the remaining evidence of the up lift in old tree stumps and soil layers. something like 30 feet.
    In the American NW there continues to be uplift (minimal) from the retreat of glacial events.

    Reply
      • I swear you posted a video a few years back from a Washington state Public station that explained why there were huge lakes in Puget Sound in the early stages of glaciation. You also posted something about Lake Missoula. It might be similar in both cases where ice dams prevented the water from flowing into the sea, and every 50 years or so the ice dams broke.

        Reply
  5. Robert, this is exactly what happens to the state of Maine. We are covered with a mile of ice every 100,000 years or so, and pushed down below sea level. That forms salt water sea shells, which appear up in the hills after the land rebounds back up several hundred feet. Best regards, Dan Tarpley, Maine

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    • Thanks. I’ve definitely heard of isostatic rebound (post-glacial rebound), but didn’t realize it involved hundreds of feet.

      Reply
      • well, since a cubic foot of water weighs 62 lbs, and compressed snow will eventually weigh that much, multiple that by a cubic mile since snow was 2 miles thick, then multiply that by the 3.8 million square miles in Canada, we’ll get to probably more than 400′ of rebound.

        But those video people are making the mistake of thinking the continents have been where they are at the altitude they are at over the last 20,000 years. The Andes Mountains were at sea level at one time, and deep underwater, too.

        Reply
  6. Well, here’s another one we can enjoy.

    Pick out a location, or two, and keep your eye on it. Also very interesting is watching the 200 mi + advance of the Adriatic Sea towards the future home of Venice, Italy, between 12,500 – 5,000 years BP.

    Advance and retreat of the Alpine glaciers during the last glacial cycle
    https://vimeo.com/294517816

    Reply
    • Also interesting to note that the glaciers have RETREATED time after time after time with no apparent help from humans. Kind of makes you wonder whether today’s warming is all that unusual, doesn’t it?

      Reply
      • Indeed.

        However, I’d already discounted that possibility (the AGW thingy).

        What is really interesting is the repeated pulses – cycles – of advance and retreat. Generally, I’d expected that the glaciers advanced from 120K BP, to the end of the last glaciation period – 10-20K BP); but, it’s much more dramatic . . per the model here.

        Note: The Adriatic Sea, like the Strait of Hormuz and the Bering Sea was simply not in existence for perhaps 100,000 years.

        Imagine the impact on the climate (weather patterns) when the circulation from the Pacific to the Arctic Ocean is cut off for such a long period of time.

        Reply
  7. Makes no sense at all. Do they mean salt water or fresh water? If the salt water recedes, that would mean ice growth. (assuming the land remain steady) It sounds to me they’re saying as glaciers retreat, salt water also retreats?? It would have to mean the opposite. As glaciers grow, waters would retreat from Puget Sound, right?

    maybe it’s a misprint. But if not, then it’s perhaps political motivation??

    Reply
    • The map doesn’t show Vancouver Island, which is to the NW. Ice blocked the gap between the Olympic Mountains and Vancouver Island, melt water built up creating a lake which blew out and the ocean rushed into the gorge the ice had carved which is a thousand feet deep.
      What a show it would have been , eh ?
      This map shows the layout better: http://www.deepzoom.com/

      Reply
  8. Do you think land rebound is affecting sea levels? There has been a small rise since the little iceage, but any more recent gains I wounder if its from land rising. Take Hudsons Bay for example, pretty shallow, alot more land around it is being exposed as it springs back and water flows out.

    Reply

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