Found some interesting sub surface geology, have question

[Ragnor]

So I'm dredging along and I am trying to figure out if someone broke the bedrock or it was broken by the river. So I follow it back off the broken slab and find the broken cap. 2 feet down stream. Probably natural. Under it is really good looking hard pack. Then it turns to a flood that carries not values. Real muddy stuff and hard packed but all brown rocks from a non gold bearing tributary. But I keep going cause i wanna see the bedrock. I dredge down to a tight, hard packed tightly layered, broken, flat, granite slabs. I have never seen this rock before anywhere in the area. Now under it is a layer of tan clay which gives way to barren blonde/yellow clay sand and gravel. Stinks like a sewage spill. The gravel is like course road sand. I drilled a 4-5 foot hole in it and it was just the same material following a rough 85 degree slope into the abyss. It was on the last day of dredging and I cannot continue for now. I moved boulders to uncover this. I never seen this material before. Must be old i figure.
Any idea what I have found by the description? I believe it's on a contact zone.

 

Amazon Forum Fav 👍

A Handbook of Civil War Bullets and Cartridges - Grab it through Amazon!

[Ragnor]

My best guess would be an ancient pond or estuary. this is in a steep canyon high in mountainous terrain. It's like a totally different time period buried under the current stream channel. Is this normal or extremely unusual?

 

[Hitndahed]

I would BET that the "stinky gravel" layer is an OLD streambed.
Sample it hard,,, I would.

 

[jere64ca]

From your description I would guess that this area was dredged before and the river has re-deposited layers of sediments over quite a few years. The "Stinks like a sewage spill." layer is undoubtedly anaerobic digestion of plant material and plant material is the first thing to refill an opened crack. If you are finding decent gold the area is replenishing from somewhere, track down the source or locate nearby ground that the old timers missed and then you will be posting pics of gold porn!

 

[Timberdoodle]

Oakview posted a video last week that may be helpful. full of great geology info as they are following old riverbeds in a mine.
http://www.treasurenet.com/forums/gold-prospecting/512193-had-forot-alli-about-video.html

 

[Ragnor]

Oakview posted a video last week that may be helpful. full of great geology info as they are following old riverbeds in a mine.
http://www.treasurenet.com/forums/gold-prospecting/512193-had-forot-alli-about-video.html

Excellent video! Havn't had time to watch the whole thing yet, just the first half but that is one of the best and most informative explanations I have ever seen.
Thanks a bunch!