The slide "10 miles north of Vancouver" (i.e. Ridgefield) isn't related to Puget Sound. Railroaders refer to the Napavine Hill as the dividing line. South of there, water works its way out of the mountains into the Columbia River in the area described in the 1917 news story above. Some of it is in the Lewis River and some of it is in the saturated soil, leading to landslides.My understanding is a lot of the Puget Sound Basin (if that's a correct geological/geographic term) is prone to slides (see below) due to volcanic and glacial soils and high water saturation, however, locating tracks right on the beach below a bluff was not a great idea geologically (kind of like the Illinois Central's original beach right of way - now inland thanks to extensive landfill) - it's like locating in the median of highways (in Chicago, the salt on the roadway negatively affects the CTA routes there, plus unattractive stations).
https://en.wikipedia.org/wiki/2014_Oso_mudslide
https://www.oregonlive.com/weather/...etween-portland-seattle-due-to-landslide.html
This time the highway stayed open. In other Decembers, the rail line has stayed open, and the highway has been closed by slides.
The Columbia and Puget Sound share slide problems as described above, but not the same water.
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