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Author Topic:   Introduction To Geology
Coyote
Member (Idle past 302 days)
Posts: 6117
Joined: 01-12-2008


Message 101 of 293 (658535)
04-05-2012 9:19 PM
Reply to: Message 100 by Taq
04-05-2012 12:41 PM


Re: Creationism as usual
What is interesting is that some creationists claim that the deposits seen in the Grand Canyon were produced by a recent global flood. One of those deposits is the Coconino Sandstone. This deposit has all of the markings of eolian deposits. IOW, there had to be a desert with wind blown sand dunes during the flood. This seems very problematic, at least to me.

Creationists are not really interested in scientific accuracy or even consistency. Their entire goal is to make things come out correctly--i.e., as they interpret scripture. Facts, especially scientific facts, only get in the way.

This lets them "prove" that the Grand Canyon is young, and to attribute it's formation to the global flood some 4,350 years ago based on the evidence of water eroding the sediments deposited by the Mount St. Helens volcano a couple of decades back. That these two examples are so different in all respects doesn't bother them because they can imagine that the results come out supporting their beliefs.

Another example of creationists being inherently anti-science while claiming to be just the opposite.

{Careful - REALLY starting to head off-topic. This topic is a geology course, not a critique of creationist alternatives - Adminnemooseus}

Edited by Adminnemooseus, : Note in red.


Religious belief does not constitute scientific evidence, nor does it convey scientific knowledge.

This message is a reply to:
 Message 100 by Taq, posted 04-05-2012 12:41 PM Taq has not yet responded

  
Coyote
Member (Idle past 302 days)
Posts: 6117
Joined: 01-12-2008


Message 233 of 293 (684900)
12-19-2012 9:37 AM
Reply to: Message 232 by Dr Adequate
12-19-2012 3:05 AM


Re: Radiocarbon Dating
This means that there's no sense in trying to carbon date a salt-water fish, a whale, a sea-otter, and so forth.

Actually we date marine organisms all the time. But we do have to include a marine correction factor, which varies from area to area. This is called Delta-R.

For the area I work in that figure is 225±35 years. This is in addition to a worldwide marine correction factor that I think is something like 400 years.

But it is always good to test these various corrections against one another.

We encountered a feature in an archaeological site a few years ago consisting of three nestled abalone shells (face up), and in the upper shell we found both halves of a large mussel shell and charcoal. Capping this we found two more abalone shells, face down.

We dated one abalone shell, one mussel shell, and the carbon. When all corrections and calibrations were applied the three dates spanned 14 years.


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 Message 232 by Dr Adequate, posted 12-19-2012 3:05 AM Dr Adequate has not yet responded

  
Coyote
Member (Idle past 302 days)
Posts: 6117
Joined: 01-12-2008


(1)
Message 235 of 293 (684915)
12-19-2012 10:45 AM
Reply to: Message 234 by RAZD
12-19-2012 10:36 AM


Re: Radiocarbon Dating - reservoir effect
In the quotation RAZD included above was the statement:

Human bone may be a problematic medium for dating in some instances due to human consumption of fish, whose C14 label will reflect the ocean reservoir. In such a case, it is very difficult to ascertain the precise reservoir difference and hence apply a correction to the measured radiocarbon age.

By using the ratios between C13 and N15 you can estimate the amount of marine carbon in a bone sample, and can then apply the appropriate correction.

As an example, we analyzed one skeleton with an estimated 92% marine carbon in the diet, so we obviously had to include that factor into the calibration. That correction changed the age by several hundred years.


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 Message 234 by RAZD, posted 12-19-2012 10:36 AM RAZD has acknowledged this reply

  
Coyote
Member (Idle past 302 days)
Posts: 6117
Joined: 01-12-2008


Message 284 of 293 (720153)
02-20-2014 1:16 PM
Reply to: Message 283 by Dr Adequate
02-20-2014 1:04 PM


Re: Wikibook
#7
This message is a reply to:
 Message 283 by Dr Adequate, posted 02-20-2014 1:04 PM Dr Adequate has not yet responded

  
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