I've been up and down Mt. Shasta several times and have probably driven right past these gems on the way. I had no idea they were there. How's that possible? From NY Times:

In the far reaches of Northern California, traffic rushes up and
down the I-5 freeway corridor without a glimpse of the Trinity Alps,
tucked just over the ridge to the west.

For most Californians, the
notion of mountains conjures up the vast Sierra Nevada. In contrast,
the Trinities are relatively pocket-sized. Sixty miles southwest of
Mount Shasta and a five-hour drive from the San Francisco Bay area, the
region exudes an off-the-beaten-path feel of a place that time is in
the process of forgetting.