Sunday, April 28, 2013

Mystery Tunnel at Discovery Bay

Late last summer I was traversing the west shore of the Quimper Peninsula on the shore of Discovery Bay along a reach lined with bedrock. The bedrock is mapped as Quimper Sandstone and includes remarkable nodules that seem to be a feature of the sandstones in Jefferson County (see here).

Nodule in Quimper Sandstone

The sandstone also has fossils along this shore reach

Perhaps due to the fossils I was looking at the base of the bluff carefully and saw this unexpected feature that warranted closer inspection.

I have made numerous inquiries and have thus far come up empty as to why this tunnel is located here. I did not go in very far as I had no torch. So its one of those mysteries that will have to wait another day to explore. From a minerals perspective there really would not be any reason I can think of to bore a tunnel into this rock formation.
I was near this site yesterday, but logistics and other work prevented a side trip.


Geoffrey Middaugh said...

As an old "caver", I was once asked to go check out old "adits" like this in southern Utah. They looked very similar to this, with the squared off top structure, and occurred in easy dig sandstone. Minerals geologists and I eventually guessed
that most likely these were the results of speculative mining claim assessment work. The "claim" owner had to perform his annual assessment work and promote the claim. He also had to encourage investors that he had a "strike". Of course, these "mines" occurred on "vacant" public land, but 100-150 years ago, most of this was vacant public land. At least, its a good story. In Utah, there was the crazy Uranium boom days of the 1950's, which encouraged the speculation, and gave "penny stocks" meaning.

DaveH said...


Dan McShane said...

Both reasonable ideas.

Anonymous said...

thanks for share..