Where'd they go? 

The omission of the Klamath Mountains is probably a bit of a shock to California geomorphologists and geologists, but it will be welcomed by beginning California geology students.  The Coast Ranges are bad enough without having to figure out that thing about the Sierra Nevadamaking them all one is nice, but it should say bounded by the Sierra Nevada on the east and north, I suppose.

Bounded by the Cascade Range to the north, the Sierra Nevada to the east, the Tehachapi Mountains to the south, and the Coast Ranges and San Francisco Bay to the west, the valley is a vast agricultural region drained by the Sacramento and San Joaquin rivers.

I'd ask for a fact check or something, but I'd be banned by the community for questioning a fact.  Still, that's quite a lot of mountain to do away with in a Wikipedia article.