Wrinkled Mercury's shrinking history

[sathearn]

Over at RatSkep, DougC recently posted a link to a new estimate, based on lobate scarp evidence, of contraction of Mercury - a reduction in radius of about 7 percent. Earlier estimates based on less complete photography from the Mariner mission in the mid-1970s, and also considering lobate scarps, estimated contraction over the planet's history of 1-3 percent. In addition to the lobate scarps, the BBC article reporting the new study also refers to "the more subtle wrinkled ridges that also criss-cross its surface."

The second link below it to the relevant thread on RatSkep.

http://www.bbc.com/news/science-environment-26564521

http://www.rationalskepticism.org/astro ... 44397.html

[meemoe_uk]

Its wrong.

That's the short Growing Earth theory response to this estimate.

I looked at the paper. The authors assume that ridges on Mercury are due to planetary contraction, then plug this assumption into the data. I couldn't find any attempt to find supporting evidence for this assumption beyond ' its what the cooling, contracting planet theory suggests '.

Ridges can be due to thrust faults. Thrust faults are due to relative motion of 2 adjoining plates or layerings of rock.
Ok, but its not legit to blindly assume effectively all ( yes, thats what they did in the paper ) thrust faults on Mercury are due to relative motion of plates due to planetary contraction.
Growing Planet theory accommodates thrust faults too. One plate can be growing faster than its adjoining plates, causing thrusting.

However I don't think all the ridge features on Mercury are thrust faults. Conventional theory doesn't consider electrical weathering \ erosion, which can explain the craters and cliffs ( scarps ) better.

>Can't wait to find out what will happen if certain individuals in the infamous Expanding Earth thread read this ...

Our response to this is the same as to every other attempt by conventional theorist to use their flawed model to explain planets. We point out the flaws. This one was easy. But despite your expression of excitement in anticipation of a Growing Earth Theorists response, I doubt your curiosity is strong enough for you to click on another forum, unless someone leads you here.

[Florian]

Growing Planet theory accommodates thrust faults too. One plate can be growing faster than its adjoining plates, causing thrusting.

Indeed, the south pole diapir of Enceladus causes wrinkling.

However I don't think all the ridge features on Mercury are thrust faults. Conventional theory doesn't consider electrical weathering \ erosion, which can explain the craters and cliffs ( scarps ) better.

What is electrical weathering erosion? Could you develop on that?

[sathearn]

>Can't wait to find out what will happen if certain individuals in the infamous Expanding Earth thread read this ...

Our response to this is the same as to every other attempt by conventional theorist to use their flawed model to explain planets. We point out the flaws. This one was easy. But despite your expression of excitement in anticipation of a Growing Earth Theorists response, I doubt your curiosity is strong enough for you to click on another forum, unless someone leads you here.

Thanks for your thoughts on the geology. My own response would have been a bit different. In an intended response to Calilasseia, I spent hours working on a long post assembling quotations from the literature on the history of interpretation of lobate scarps as contractional features, including quotes from S.R. Taylor, R. Greeley and other authors whose names I don't remember at the moment, and also what Carey said on the subject. Unfortunately, it was all lost when my computer crashed, and simultaneously deflating of my motivation to repeat the exercise. But basically, I had wanted to convey information about how this specific topic (lobate scarps on Mercury and the Moon) has been discussed over the 40 years preceding the news item - including the basic fact, which Calilasseia didn't seem to be aware, that this is a topic with a history known to informed EE proponents and sympathizers, not something with potential to blindside them. I wanted to write a post that would be helpful to everyone interested in better comprehending the reasoning which has previously been put forward, regardless of which camp they belong, without grinding any axes. Admittedly, I have not seen arguments clear and cogent enough to be convincing one way or the other.