Ice layers depicting age


#1

One of the threads had reference to how do we know the age of earth and universe, and started with tree rings, then ice layers, etc. With reference to ice layers, an assumption was made that annual layers were formed, about 130,000 in Greenland, and 740,000 in the antarctic. Last winter, I had looked at the snow on edge of my garage, and noticed that it was not homogeneous, but layered, even though it was only a few months old. Every time it partially melts during the winter, it formed a different layer. From that observation, I realized that the parameter of one layer per year was an assumption that could be challenged. During really cold weather, you usually get less snow than during milder winters. During milder winters you get a number of melting events. If this is combined with ash, or dust in the atmosphere depositing on snow, causing surface melting even at subzero temperatures, then can we be sure of only annual layers being formed? For colder global locations where snow exists all year around, these layers could be formed all year around, especially in the summertime. Can we prove, or can we even assume without proof, that we could not get twenty layers per year formed easily? I am also reminded of the actual evidence of ice formation in Greenland, where some planes were covered by 260 feet of ice in 50 years… this would be about 5 feet per year. This rate under the relatively low snowfalls of present time… compared to the high annual rates up to 42 feet that fall in various places in the mountains of Canada, or over 52 feet in some of the USA or Japanese mountains. The greenland ice sheet is 4000 feet thick, which at 5 feet per year, would have taken less than 1000 years to lay down. To equate this to 130,000 years seems to take some mental gymnastics that are unreasonable. Any thoughts?


#2

Okay, so here are some following thoughts after some research. Ice at surface formed from snow may have a density of about .5 gm/cm3, while maximum density of ice would normally be about 92 gm/cm3. This means that even with compression, ice in the ice sheets would be assumed to be laid down at a rate of about 2.5 m/yr if rates were uniform to today, leading to the conclusion that it would have taken about 2000 years to lay down in Greenland. If snowfall rates were heavier in the past, the time would have been less. Is there justification for thinking that snowfall rates would have been less than today over the supposed 130,000 years assumed in hypothesis? Is the evidence of what we can actually see happen not weighty evidence?


(Brad Kramer) #3

@johnZ I found this article that addresses some of your (good) questions:

The GISP2 Ice Core:
Ultimate Proof that Noah’s
Flood Was Not Global


#4

Thanks Brad for that article. It was well written. Relatively easy to understand. Which brought a few confusing issues to mind. One is that although the methods seem to correlate for part of the core, they cannot all be used to corroborate each other all the way down.
To start with, although there was fortunately an available volcano to correlate for a high spike in sulphuric acid within known history for the ECM measurements, there did not appear to be an attempt to correlate to a volcano histogram of all known volcanoes. Beyond known history of the last 2000 years, we enter more and more into speculation about impact of volcanoes, wind patterns amount of dust emitted per volcano. Not to say the inference is incorrect, just that it is much more speculative.

Using dust as an indication of an annual layer is problematic for me. In this report there is no mention of the correlation of nitric acid to dust. In addition, dust is caused by events, not by seasons. Dust (and smoke) moves thousands of miles through the atmosphere, and if constant in the air, could be deposited after many snow falls.

With regard to the O18 -O16 ratio, which seems to be only good for 10000 yrs BP, it would seem difficult to prove that conditions such as ocean currents have not changed, or that significant events bringing in changing wind patterns could not influence this ratio enough to be mistaken for an annual pattern. Moisture derived from equatorial locations in winter would be comparable to summer moisture from northern Atlantic oceans in summer in terms of isotope ratios. But even the impact of the gulf stream vs evaporated moisture from the bering strait and elsewhere would seem to make this unreliable.

The theory about hoar frost was interesting. They postulate that hoar frost snow only forms in summer, due to sunlight heat, which makes sense. However, while the sun does not shine in Greenland in winter, it snows all year around, mostly in summer in the interior. If it did not snow at all in the winter, then the core would not show the winter effect (lack of hoar snow). If snow fall in summer exceeded four inches, then with the sun and hoar frost snow effect affecting only the top two inches, a quasi winter effect would be indicated, leading falsely to an additional annual measurement. It is interesting that in the interior of Greenland, according to Wiki, measurements of precipitation are often made by counting annual layers, since no other measurement devices have been made available in the sparsely populated areas. Of course, measuring annual layers could be a circular argument if not corroborated by actual snowfall measuring devices. Perhaps Wiki is now out of date on this.

There was no mention of the effect of cloud cover on the formation of hoar snow. We know that in some places the sun does not shine for months due to cloud. Of course, in those places, precipitation is also high, usually in the form of rain, but can we rule out the effect of cloudy weeks with snow fall during the summer creating an quasi-annual effect?

There is an assumption that annual layers become thinner and thinner as they get deeper in the profile. But there is a physical limit to compression of ice, which should be achieved long before it reaches a 2000m depth. The information I have seen on glacial ice density does not reveal values above .92gm/cm3, which is perhaps 2.5 times as dense as settled snow. While the air in the snow and ice becomes compressed, there is still a limit, and so it does not work for me that layers become progressively thinner forever in the profile with depth.

It is interesting that the incident of the lost planes in Greenland demonstrates a 7 foot snow fall area. The article indicates that is the reason for the depth of the planes found under the ice. But the article also makes a statement that several annual layers are found within the first few inches near the surface. This is inconsistent and unexplained. How could an annual 7 foot snow fall result in several annual layers within a few inches at this location?


(Brad Kramer) #5

John,
I don’t have the expertise to answer your questions sufficiently. I found the link to the article in my original comment on the site ageofrocks.org, and this blog in particular: http://ageofrocks.org/100-reasons-the-earth-is-old/

Perhaps some other, more scientifically literate commenters will jump into the discussion with you.


#6

Thanks Brad. An additional thought I had was how long it really takes to form hoar frost… I know it can form in a day or two at home, and be heavy enough to bend tree branches. At that rate there needs to be no assumption that it is merely seasonal, as it can form after and between various snowfall events. I keep on thinking about these things…


#7

After my own speculations on possibilities for subannual hoar frost, I discovered that Michael Oard (Aug 2004) had already responded to Heely’s arguments and descriptions of the methods of counting annual layers in the ice cores. Following is a response to only one of Heely’s discussed methods:

“In regard to each annual layer counting method, much could be written to show that Seely misunderstands the methods. … Seely states that surface hoar frost forms only during the summer due to sunshine and fog. However, surface hoar frost is only a minor player in the annual layer method; depth hoar is the main marker.17 Depth hoar develops when a large, vertical temperature gradient causes vapour to sublime, diffuse and crystallize in a layer.18 This occurs just below the surface, mainly during the summer. However, it has been observed from snow pits that many depth-hoar/wind slab couplets can form each summer.19,20,21,22 Alley and colleagues measured about 15 alternating depth-hoar/finer-grained wind crusts per year in snow pits at the top of the Greenland Ice Sheet.23,24 These layers were observed to have formed by individual storms.24 Although considered rare today, winter depth hoar can also form, but it is normally thin and discontinuous.23,25,26 Storms can cause depth hoar layers if the temperature gradient is sufficient during the changes between warm and cold sectors of storms. These depth hoar complexes, as they are called, can usually be counted as annual layers in the top portion of the GISP2 core. It is more likely that a subannual depth hoar layer formed by a storm would be counted as an annual signal, if the snowfall were significantly higher in the past, as in the Creation/Flood model for the middle and lower portions of the ice core.”

Contrary to the National Geographic article “war on science”, Oard’s response shows that YEC creationists do not have a war on science, but rather investigates scientist claims quite scientifically.


(system) #8

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