Bex, you essentially asked “what use is half a wing”? The examples I gave you could be interpreted as “half a wing,” i.e. they are not fully-formed wings. Creatures do not suddenly evolve half-parts that are not useful to them either as limbs or wings. Such unbeneficial mutations would lead to the death of the organism. However, we do see gradual changes in the morphology of species over time in the fossil record, such as the incremental disappearance of limbs in the whale. Flightless birds have other uses for their wings. The penguin is a wonderful example of how a bird that once flew, now has a new and very useful function for those wings, which have evolved into flippers. I’m not arguing that vestigial wings are functionless, and lack of functionality is not part of the definition of a vestigial organ.
Why do scientists say that penguins’ flippers used to be wings? The fossil record.
Fossil Penguins: A Journey to the Bottom of the World The consensus is that penguins did indeed originate from an ancestor that flew some 40 million years ago, quite possibly from the order Procellariformes, as I have already demonstrated. What then caused the present (and past penguins) to lose their capability to fly? A few explanations have arisen. One of these theories is known as "systemic mutation" (Goldschmidt), also known as "typostrophism" (Schindewolf). This account is unlikely since radical changes (flight to no flight) can occur on a small evolutionary scale without the requirement of extensive mutations occurring at once. Nevertheless, the inability to fly is still seen as a viable adaptation, since radical changes that are not adaptations typically lead to extinction. We have already given two possible theories as to how birds acquired flight. Now we have discussed how penguins may have lost that ability to fly.
You said:
The total theoretical column depth is 100 miles
You need to give citations when making assertions like this, but I think I found where you got it from – Henry Morris, “What is Creation Science?”, 1987.
There is absolutely no geologist who believes that the geological column must be 100 miles thick. There were some calculations made which added from around the world in many different basins what the thickest sediment of each age were. For example (numbers and places made up) they might take 20,000 feet of Cambrian strata from the Arbuckle mountains and add that to 25,000 feet of Ordovician strata from Bolivia etc. This then adds to 100 miles. However, this is taking the most rapid sedimentation rates found on earth and saying those rates must be found all over the earth everywhere. The Mississippi River and the Amazon river pour lots of sediment into a limited area. The rate of deposition is quite high. It is higher at the mouth of the
Mississippi than anywhere along the east coast of the United States. Yet every day new sediment is deposited at both places. Both places have an entire record of sediment for the past 2 million years. The Mississippi mouth has about 5000 feet and the Georges Bank region off Massachusetts has only about 100 feet (See Geological Studies of the COST Nos. G-1 and G-2 Wells United States NOrth Atlantic Outer Continental Shelf US Geological Survey Circular 861, p. 46.)
Hay River Embayment (van Hees, 1964) - a depositional area northwest of the Peace-Athabasca Arch, developed on the Interior Platform, containing remnants of rocks that have been interpreted as being equivalent to Lower and Middle Cambrian units of central Alberta. The rocks have not been dated
Lesson one: stop using sources that are decades old.
from
Bulletin of Canadian Petroleum Geology; December 1999; v. 47; no. 4; p. 534-547 The impetus provided by Lithoprobe's Alberta Basement Transect program has led to a tenfold increase in paleomagnetic data for strata in the Western Canada Sedimentary Basin (WCSB). This paper aims to provide a synthesis of this research with emphasis on the results to date. They show that paleomagnetic methods can be used to reliably: (1) date dolomitization in the strata, in petroleum reservoirs, and in Mississippi Valley-type (MVT) zinc-lead hydrothermal ore deposits; (2) narrowly constrain the ages of folding and faulting events; and, (3) orient stored core for further geologic analysis to provide other useful geologic information. Except for a few specimens in anhydrite and a few more in limestone that retain a primary remanence, all of the few thousand specimens from a few hundred sites in dolomites and zones of MVT mineralization throughout the WCSB define ages corresponding to the time span of the Laramide Orogeny. Thus, they support geologic models that attribute dolomitization, MVT mineralization and, by inference, related geologic phenomena to regional fluid flows spawned by Laramide orogenesis.
This area is now well-studied because people are prospecting for oil there.
Lesson two: Morris doesn’t know what he’s talking about.
Radiometric dating next. It’s getting tedious to laboriously refute your pasted links from creationist websites.
Here is a pasted link of my own that answers Morris’ perceived problems with potassium-argon dating.
Argon may be incorporated with potassium at time of formation. This is a real problem, but it is easily overcome either by careful selection of the material being dated or by using 40Ar/39Ar dating instead of K-Ar dating.
In the case of the claim about recent lava yielding dates that are millions to billions of years old, H. M. Morris (1974) misstated the facts concerning these "anomalous" dates as published in Funkhouser and Naughton (1968). The main misstatements of fact by Morris are as follows:
• It was not the lava that was dated, but inclusions of olivine, called "xenoliths", present within the lava. These gave anomalously old age because they contained excess argon that the enclosing lava did not.
• Morris failed to mention that the lava matrix without the xenoliths was dated and found to be too young to date using potassium-argon. (Funkhouser and Naughton [1968, 4603], stated that the matrix rock "can be said to contain no measurable radiogenic argon within experimental error.") This is consistent with the recent age of lavas and the state of the art of K-Ar dating at that time. The presence of excess argon was only a problem for the xenoliths but not for the lava containing them.
Morris cited other examples of anomalous dates produced by excess argon and falsely claimed that it is a universal problem for K-Ar dating. The problem is not universal, as the majority of minerals and rocks dated by K-Ar do not contain the excess argon. Where excess argon is a problem, accurate, reliable dates typically can be obtained using 40Ar/39Ar dating, as demonstrated by Dalrymple (1969) and Renne et al. (1997) and discussed by Dalyrmple (2000).
2. Morris's complaints are dated in that, for the most part, geologists no longer use the K-Ar dating technique as was practiced in 1974. Instead, K-Ar dating has been largely replaced by the related 40Ar/39Ar dating technique.
What’s more, RATE was a team of creationists with legitimate credentials who set out to attack the validity of radiometric dating. They ended up having to admit that large amounts of radioactive decay had occurred and have been trying to come up with a YEC explanation for this. You can read about them
here.
Morris states, rightly, that there can be some problems with getting an accurate radiometric result. These potential problems are recognised and provision is made for them. No geologist takes a single sample from a single rock and assumes a completely accurate date from it. You can read about radiometric dating at
Wikipedia:
Although radiometric dating is accurate in principle, the precision is very dependent on the care with which the procedure is performed. The possible confounding effects of initial contamination of parent and daughter isotopes have to be considered, as do the effects of any loss or gain of such isotopes since the sample was created.
Precision is enhanced if measurements are taken on different samples from the same rock body but at different locations. Alternatively, if several different minerals can be dated from the same sample and are assumed to be formed by the same event and were in equilibrium with the reservoir when they formed, they should form an isochron. Finally, correlation between different isotopic dating methods may be required to confirm the age of a sample.
The precision of a dating method depends in part on the half-life of the radioactive isotope involved. For instance, carbon-14 has a half-life of about 6000 years. After an organism has been dead for 60,000 years, so little carbon-14 is left in it that accurate dating becomes impossible. On the other hand, the concentration of carbon-14 falls off so steeply that the age of relatively young remains can be determined precisely to within a few decades. The isotope used in uranium-thorium dating has a longer half-life, but other factors make it more accurate than radiocarbon dating.
If radiometric dating were as wildly inaccurate as Morris seems to want to claim, then there should be nothing but random scatter showing up on radiometric graphs. On the contrary, the dates agree with each other quite well and most anomalous dates, which are rare, are due to a variety of possible errors. Does Morris think that geologists are not aware of this?
from
Consistent Radiometric Dates:
One of the main objections to radiometric dating (on the part of young earth creationists) is that radiometric ages do not agree with each other or that contamination renders ages meaningless. In fact, the claim is partially true. Early mass spectrometers were not as sensitive as machines today and the methods for separating, cleaning and analysis were less sophisticated. Although ye-creationists like Snelling talk about contamination of isotopic systems as if it were a foreign concept to modern geology, most geochronologists routinely check for possible contamination using a variety of methods. In addition, geologists recognized that rocks could be contaminated with excess daughter or parent or loss of parent/daughter that would also affect the age as determined by radiometric methods. Creationists have seized upon these discoveries and held them forth as evidence that radiometric dating is inaccurate. But is this the case? Simply put each radiometric system is based on the assumption that each system has a different half-life (derived from the decay 'constant' which is simply the length of time it takes for 1/2 of the radioactive parent to decay to a stable daughter). In addition to variable half-lives, each mineral will 'close' at different temperatures (closure, is simply defined as the point where no daughter/parent is lost or gained*). There are a number of different methods that geologists use to check for loss/gain and these are incorporated into most analyses (isochron methods, stepwise degassing etc). If radiometric decay rates are not constant and rocks behave as open systems, it would be the exception, rather than the rule, for ages to agree with one another.
Addressing Morris’ comments about pseudo-isochrons, a geologist has given me the following information:
The most common cause of a false isochron is a mixing isochron, where two sources with different isotopic makeup mix. There's a good discussion and simple example at
Isochron Dating: Mixing of Two Sources. You might have to read the beginning part to understand the notation.
Some creationist once published a scenario in which he demonstrated that mixing of three sources of peculiar composition (IIRC, one source had to contain only radiogenic daughter and no other isotopes of the daughter, which never happens) could form an isochron and the mixing plot described in the reference above wouldn't detect it. I can't find a reference now. But the idea that such things happen regularly is pretty ludicrous.
IMHO, the major indicator of the reliability of radioisotope dating is the excellent correlations between different radioisotope methods and the excellent correlations between radioisotope methods and non-radioisotiope methods.
He also adds, about isochron dating:
In isochron dating, the initial parent/daughter ratio is one of the results of the analysis.
We've never found a rock that's 4.55 billion years old. We have rocks that are around 4 billion years old, and we've found zircon grains that are 4.4 billion years old. The 4.55 billion year age of the Earth is derived from Pb-Pb dating, an isochron method (and therefore not affected by initial daughter problems) that is a little too complex to explain here.
Probably the most popular technique for age determination today is U-Pb concordia-discordia, which is not an isochron technique but is instead a simultanous application of two independent dating methods. This method is very widely applicable, the half-life of uranium is known to far greater precision than any other half-life, and it can even give a valid age if there has been "open system behavior" (e.g. loss of Pb to diffusiion or leaching and what-not).
U-Pb dating requires that there be no significant daughter isotope at solidfiication, so it is used solely on minerals which strongly reject lead at solidification, usually zircons. It's physically impossible to solidify a zircon with enough lead to screw up U-Pb dating, unless there's also so little uranium that the dating wouldn't work anyway. The sexiest U-Pb dating is done essentially in situ in a Sensitive High-Resolution Ion MicroProbe, or SHRIMP (see
Centre for Excellence in Mass Spectrometry). SHRIMP is so sensitive, and needs so small a sample size, that it can date sedimentary rocks by looking at the zenotime that forms between grains when the rock lithifies (see
U-Pb SHRIMP Dating of Diagenetic Xenotime). Essentially all other radioisotope techniques are restricted to igneous rocks.
Then there's K-Ar dating, beloved of creationists and almost the only one they ever discuss. K-Ar does require an "assumption" of no radiogenic argon at solidification, but since argon is a gas this is almost always a good "assumption". But some errors have occurred because of "excess argon". However, any sample that can be dated by K-Ar can also be dated by Ar-Ar, an isochron method, and this is often done.
K-Ar dating is quite low cost and simple, and is still done, but is essentially never published today without the cross-check of another dating method. For some examples of rocks dated by multiple methods, see
Consistent Radiometric dates and
Radiometric Dating.
Radiometric dating is one of the best methods there is of obtaining geological dates. For a more detailed explanation of how it works, including graphs which plot dates obtained by these methods, then please have a look at any of the links provided here.
