Cone Outcrops

We were very busy today, but not on the trail. We are getting ready to move so it was time to do laundry, clean house, dump tanks, fill up the propane tanks, fuel the car, etc., etc., etc.. Nothing exciting, but it has to be done.

What I do have of interest is a response from Cheryl Jaworowski, the Yellowstone Park Geologist. Remember the pictures of the cone outcrops? (You can click on them to make them bigger.)

We were particularly interested in knowing how the cone-shaped outcrops formed - all of the formations that have the cone shape, even though some are larger than others, all seem to have the same slope.

I emailed the Yellowstone Park Geologist and here is her reply -

Dale and Frederick,

Thank you for sending the photographs, descriptions and coordinates. You did make interesting observations and photograph interesting outcrops along the Black Butte Trail.

According to bedrock geologic maps, there are two geologic formations within the Absaroka Volcanic Supergoup along the Black Butte Trail: the Mount Wallace Formation and the Fortress Member of the Sepulcher Formation.  Both rock units are related to andesitic volcanism about 50 million years ago. If you conducted internet searches on these names, you might find other interesting information.  

Also, I read the 2011 Roadside Geology of Yellowstone Country by William Fritz and Robert Thomas.  On page 104, they have a picture of Black Butte and discuss that it is a stock within the Absaroka volcaniclastic rocks. Essentially, the molten material cooled underground to form the stock.  Overlying material was eroded and we now see the stock at the ground surface.

The rocks in your pictures do look like erosional remnants.  Both physical and chemical weathering processes can form these shapes.

Let me know if you have other questions.

Cheryl Jaworowski, Ph.D.

Geologist

Yellowstone Center For Resources

Yellowstone National Park, WY 82190

Phone: (307) 344-2208

Fax: (307) 344-2211

Email: cheryl_jaworowski@nps.gov

I'm not sure that completely answers our question, but maybe I'll wait and discuss it with our resident geologist.

Meanwhile, with no adventures to report on today, here are pictures of the grandkids that we are getting ready to see. We can't wait!!!!

Jacob as we remember him from this past summer.

Nathan, the eagle, getting ready for Halloween.

Pretty proud of that costume!

Maura enjoying fall in New England.