27 March 2020
Friday fauxld: a false syncline in Titus Canyon
Posted by Callan Bentley
Can it really be only two weeks ago that I was geologizing in the California desert?
My students and I saw this scene in Titus Canyon, just below Leadville.
Naturally enough, we keyed into this feature specifically:
It looks like a syncline (or “synform,” as lower Titus Canyon teaches us to more carefully say)!
…But: there’s no fold here at all! It’s a trick of the outcrop surface.
These are uniformly right-dipping strata, but in some places the outcrop surface is parallel to the true dip of the strata, showing them to be most steeply inclined, and sometimes parallel to the strike of the strata, which gives their trace a horizontal expression, and everywhere else the outcrop surface is oblique to the strike and the dip at some angle, giving them an “apparent dip” that is somewhere between the true dip and horizontal:
No fold at all in this photo: it’s a faux fold, a “fauxld!”
Enjoy, and be safe and be healthy, and I hope sincerely that you and your loved ones are spared the ravages of COVID-19. I think it’s unlikely to leave any of us truly unscathed, but we’re still in the early days of the disaster.
It may seem indulgent and frivolous, but for me, the Friday fold represents a regular ritual to return to in these extraordinarily stressful times.
Here’s a handheld GigaPan of this outcrop:
Link 0.13 Gpx GigaPan by Callan Bentley
Thanks, this one is a great teaching opportunity.
For years, that “fold” had a Park Service sign in front depicting it as a fold. It was removed several years ago – someone wised up.
I would post a picture of the old sign if I could. But I found a 1999 post that has a picture of the sign ( though without the “fold” in the background – trust me, it was in front of that feature).
Scroll down past the recap of the visit to Leadfield – most of the way to the end.
Last time I was there, the cement bricks for the base of the signage were still there. I always chuckle when I drive by and see the base for that sign.
Cool — Here’s a direct link to the photo: https://images.squarespace-cdn.com/content/v1/53505212e4b08071626630b8/1397933727579-CN8YO9COIEBRYEINMHIV/ke17ZwdGBToddI8pDm48kL3VKmwKI3leYB51VJjLFB8UqsxRUqqbr1mOJYKfIPR7LoDQ9mXPOjoJoqy81S2I8N_N4V1vUb5AoIIIbLZhVYxCRW4BPu10St3TBAUQYVKcgK5SGg9Ovb1yloBBOHcruw_mYLfAhRzzgArFCB07Dw0L8n4JypuoE5Tg6Wg5Oyvs/image-asset.jpeg?format=300w
Maybe we ought to put-up a tasteful lookin’ sign with the old interpretation and the real prospective. Of course the Park Service would be out for somebody’s hide.