I'm curious why you can't? I'm guessing that seawater permeation would alter the isotope distribution, but I also wonder if the alteration is predictable in some fashion. Does seawater affect the decay rate in some fashion?
Yes, that's exactly it. You can sometimes adjust if the water was constant and you have some other clock you can calibrate to (for example the bottom of the ocean at a specific depth).
But if you have water that came and went then the errors are too large.
"10,000 year old stone tools found in Redmond" doesn't sound as good. They were probably just used by ancient Microsoft programmers in building a very early version of Windows, which is why this is on Hackernews at all.
Normally I would use "suburban X" to describe one of the more suburban parts of X, not a different, nearby city, which I would instead call "suburb of X". I guess maybe this is because I grew up in what was clearly the suburbs despite being legally part of the primary city of the region (Phoenix, which is more or less a suburb of itself).
The difference might not matter in places like where I'm from, where Phoenix blends into Glendale or Mesa or whatever. In Seattle it does feel more like two nearby cities than one mass of suburbs, though, since there's a big physical boundary (Lake Washington) between them.
Edit:
Further muddying the waters, I kind of lump the Eastside into one "city" from a geographical perspective, though legally it's Bothell, Kenmore, Redmond, Bellevue, etc. I do think of Seattle as a separate thing.
Some parts of California make this easier by calling the county by the name of the biggest city. This makes local geographical references easier for non local audiences. Eg. The desalination project in Carlsbad -> San Diego County -> California -> United States. Even though Carlsbad isn't the city of San Diego, CNN might report that a desalination project is in progress in San Diego, and still be relatively accurate.
It seems that people do this in conversation by default already, even if the legal boundaries don't conveniently match with what they mean.
I'll have to plead ignorance, then! The only times I've gone to the northern cities on the Eastside are biking on the Burke, and since I'm not constantly checking a map it's not clear to me exactly where the boundaries are between Lake Forest Park, Kenmore, Bothell, etc.
As the roads go, Kenmore is just on the western side of the lake (its actually right above it, but there is a huge deadspace to the south of residences), you keep going that way and you are quickly in Seattle. If you go along the eastern side of the lake, you are basically in Kirkland which abuts Bellevue.
Bothell is basically equidistant from Seattle, Everett, and Bellevue (I was living in Snohomish County, so closer to Lynwood and Everett), basically under all those cities's influences.
That would explain the discrepancy between 3,500 and 10,000 years.